Dr Heath Jones

University retention and completion rates underestimate true levels of student participation because of their reliance on measurements taken at commencement (or census date) and end of a program. As a result, these statistical snapshots miss what happens in between, failing to capture the true reach of the teaching and learning process, as well as the effort and resources involved. This is problematic when these numbers drive debate over higher education policy or institutional decisions over resource allocation. Here we propose a way of turning retention statistics into a more meaningful measurement of student participation, that we term engagement. In the context of this article, engagement is a calculated quantity based on the time-averaged student retention of a program or course. We argue that it addresses the shortcomings of snapshot metrics and provides some much-needed insight into student participation. We motivate its adoption and illustrate its use with worked examples, as a guide to practitioners, researchers and policymakers in the field.

One of the fundamental goals of modern astrophysics is to estimate the physical parameters of galaxies. We present a hierarchical Bayesian model to compute age maps from images in the H a line (taken with Taurus tunable filter, TTF), ultraviolet band (GALEX far UV, FUV), and infrared bands (Spitzer 24, 70, and 160 µm). We present the burst ages for young stellar populations in a sample of nearby and nearly face-on galaxies. The H a to FUV flux ratio is a good relative indicator of the very recent star formation history (SFH). As a nascent star-forming region evolves, the H a line emission declines earlier than the UV continuum, leading to a decrease in the H a/FUV ratio. Using star-forming galaxy models, sampled with a probabilistic formalism, and allowing for a variable fraction of ionizing photons in the clusters, we obtain the corresponding theoretical ratio H a/FUV to compare with our observed flux ratios, and thus to estimate the ages of the observed regions. We take into account the mean uncertainties and the interrelationships between parameters when computing H a/FUV. We propose a Bayesian hierarchical model where a joint probability distribution is defined to determine the parameters (age, metallicity, IMF) from the observed data (the observed flux ratios H a/FUV). The joint distribution of the parameters is described through independent and identically distributed (i.i.d.) random variables generated through MCMC (Markov Chain Monte Carlo) techniques.

We present the first major release of data from the SAMI Galaxy Survey. This data release focuses on the emission-line physics of galaxies. Data Release One includes data for 772 galaxies, about 20 per cent of the full survey. Galaxies included have the redshift range 0.004 < z < 0.092, a large mass range (7.6 < logM*/M¿ < 11.6), and star formation rates of ~10-4 to ~101M¿ yr-1. For each galaxy, we include two spectral cubes and a set of spatially resolved 2D maps: single- and multi-component emission-line fits (with dust-extinction corrections for strong lines), local dust extinction, and star formation rate. Calibration of the fibre throughputs, fluxes, and differential atmospheric refraction has been improved over the Early Data Release. The data have average spatial resolution of 2.16 arcsec (full width at half-maximum) over the 15 arcsec diameter field of view and spectral (kinematic) resolution of R = 4263 (s = 30 km s-1) around Ha. The relative flux calibration is better than 5 per cent, and absolute flux calibration has an rms of 10 per cent. The data are presented online through the Australian Astronomical Observatory's Data Central.

The detection of black hole binary coalescence events by Advanced LIGO allows the science benefits of future detectors to be evaluated. In this paper, we report the science benefits of one or two 8 km arm length detectors based on the doubling of key parameters in an Advanced LIGOtype detector, combined with realizable enhancements. It is shown that the total detection rate for sources similar to those already detected would increase to ~ 103-105 per year. Within 0.4 Gpc, we find that around 10 of these eventswould be localizable to within ~ 10-1 deg2. This is sufficient to make unique associations or to rule out a direct association with the brightest galaxies in optical surveys (at r-band magnitudes of 17 or above) or for deeper limits (down to r-band magnitudes of 20) yield statistically significant associations. The combination of angular resolution and event rate would benefit precision testing of formation models, cosmic evolution, and cosmological studies.

We present a photometric investigation into recent star formation in galaxy clusters at z ~ 0.1. We use spectral energy distribution templates to quantify recent star formation in large Xray- selected clusters from the LARCS survey using matched GALEX near-ultraviolet (NUV) photometry. These clusters all have signs of red sequence galaxy recent star formation (as indicated by the blue NUV - R colour), regardless of the cluster morphology and size. A trend in environment is found for these galaxies, such that they prefer to occupy low-density, highcluster- radius environments. The morphology of these UV-bright galaxies suggests that they are in fact red spirals, which we confirm with light profiles and Galaxy Zoo voting percentages as morphological proxies. These UV-bright galaxies are therefore seen to be either truncated spiral galaxies, caught by ram pressure infalling into the cluster, or high-mass spirals, with the photometry dominated by the older stellar population. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

We investigate the morphology dependence of the Tully-Fisher (TF) relation, and the expansion of the relation into a three-dimensional manifold defined by luminosity, total circular velocity and a third dynamical parameter, to fully characterize spiral galaxies across all morphological types. We use a full semi-analytic hierarchical model (based on Croton et al.), built on cosmological simulations of structure formation, to model galaxy evolution and build the theoretical TF relation. With this tool, we analyse a unique data set of galaxies for which we cross-match luminosity with total circular velocity and central velocity dispersion. We provide a theoretical framework to calculate such measurable quantities from hierarchical semi-analytic models. We establish the morphology dependence of the TF relation in both model and data. We analyse the dynamical properties of the model galaxies and determine that the parameter s/VC, i.e. the ratio between random and total motions defined by velocity dispersion and circular velocity, accurately characterizes the varying slope of the TF relation for different model galaxy types. We apply these dynamical cuts to the observed galaxies and find indeed that such selection produces a differential slope of the TF relation. The TF slope in different ranges of s/VC is consistent with that for the traditional photometric classification in Sa, Sb and Sc. We conclude that s/VC is a good parameter to classify galaxy type, and we argue that such classification based on dynamics more closely mirrors the physical properties of the observed galaxies, compared to visual (photometric) classification. We also argue that dynamical classification is useful for samples where eye inspection is not reliable or impractical. We conclude that s/VC is a suitable parameter to characterize the hierarchical assembly history that determines the disc-to-bulge ratio, and to expand the TF relation into a three-dimensional manifold, defined by luminosity, circular velocity and s/VC. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

A combination of BRI photometry and archival Chandra X-ray data have been used to analyse the effects a minor merger has on the galaxy population of A1664.We utilize adaptive smoothing techniques in the 2D spatial distribution of cluster galaxies to reveal substructure~800 kpc south of the cluster core. We identify this substructure as most likely the remnant core of a merging group which has passed pericentre and responsible for triggering a cold front in the cluster core. We define two samples to represent two different environments within A1664 in accordance with the location of the substructure. We apply a morphological analysis using concentration-asymmetry-clumpiness, M20 and Gini to these samples to deduce if there has been any significant effect on the cluster galaxies due to this interaction. We find that there are more asymmetric galaxies found in the inner sample (at the 3.7 s level) which are likely due to galaxy-galaxy interactions as the merging group passed through core passage. No other differences were found between the inner and outer cluster in our morphological analysis, which we attribute to the limited resolution of our imagery. The colour profiles of the galaxies are found to be consistent with the morphology-density relation suggesting that there is no unique environmental effect in A1664 that has enhanced galaxy transformations. This study favours the star formation of cluster galaxies being quenched well before they are able to interact with the merging group and demonstrates that a minor cluster merger has little effect on the observable parameters of cluster galaxies such as morphology and colour. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

We report the 6dFGS Fundamental Plane (6dFGSv) catalogue that is used to estimate distances and peculiar velocities for nearly 9000 early-type galaxies in the local (z < 0.055) universe. Velocity dispersions are derived by cross-correlation from 6dF V-band spectra with typical S/N of 12.9Å-1 for a sample of 11 315 galaxies; the median velocity dispersion is 163 km s-1 and the median measurement error is 12.9 per cent. The photometric Fundamental Plane (FP) parameters (effective radii and surface brightnesses) are determined from the JHK 2MASS images for 11 102 galaxies. Comparison of the independent J-and K-band measurements implies that the average uncertainty in XFP, the combined photometric parameter that enters the FP, is 0.013 dex (3 per cent) for each band. Visual classification of morphologies was used to select a sample of nearly 9000 early-type galaxies that form 6dFGSv. This catalogue has been used to study the effects of stellar populations on galaxy scaling relations, to investigate the variation of the FP with environment and galaxy morphology, to explore trends in stellar populations through, along and across the FP, and to map and analyse the local peculiar velocity field. © 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

Using the 2MASS near-infrared photometry and high-signal-to-noise HI 21-cm data from the Arecibo, Green Bank, Nancay, and Parkes telescopes, we calculate the redshift-independent distances and peculiar velocities of 2018 bright inclined spiral galaxies over the whole sky. This project is part of the 2MASS Tully-Fisher survey (2MTF), aiming to map the galaxy peculiar velocity field within 100 h-1 Mpc, with an all-sky coverage apart from Galactic latitudes |b|<5°. A x2 minimization method was adopted to analyse the Tully-Fisher peculiarvelocity field in J, H, and K bands, using a Gaussian filter. We combine information from the three wavebands, to provide bulk flow measurements of 310.9 ± 33.9 , 280.8 ± 25.0, and 292.3 ± 27.8 km s-1 at depths of 20, 30, and 40 h-1 Mpc, respectively. Each of these bulk flow vectors points in a direction similar to those found by previous measurements. At each of the three depths, the bulk flow magnitude is consistent with predictions made by the ¿ cold dark matter (¿CDM) model at the 1s level. The maximum likelihood and minimum variance method were also used to analyse the 2MTF samples, giving similar results.

We present scale-dependent measurements of the normalized growth rate of structure fs8(k, z =0) using only the peculiar motions of galaxies.We use data from the 6-degree Field Galaxy Survey velocity sample together with a newly compiled sample of low-redshift (z < 0.07) Type Ia supernovae. We constrain the growth rate in a series of ¿k 0.03 h Mpc-1 bins to 35 per cent precision, including a measurement on scales >300 h-1 Mpc, which represents one of the largest scale growth rate measurement to date. We find no evidence for a scaledependence in the growth rate, or any statistically significant variation from the growth rate as predicted by the Planck cosmology. Bringing all the scales together, we determine the normalized growth rate at z = 0 to 15 per cent in a manner independent of galaxy bias and in excellent agreement with the constraint from the measurements of redshift-space distortions from 6-degree Field Galaxy Survey. We pay particular attention to systematic errors. We point out that the intrinsic scatter present in Fundamental Plane and Tully-Fisher relations is only Gaussian in logarithmic distance units; wrongly assuming it is Gaussian in linear (velocity) units can bias cosmological constraints.We also analytically marginalize over zeropoint errors in distance indicators, validate the accuracy of all our constraints using numerical simulations, and demonstrate how to combine different (correlated) velocity surveys using a matrix 'hyperparameter' analysis. Current and forthcoming peculiar velocity surveys will allow us to understand in detail the growth of structure in the low-redshift universe, providing strong constraints on the nature of dark energy.

We derive peculiar velocities for the 6dF Galaxy Survey (6dFGS) and describe the velocity field of the nearby (z < 0.055) Southern hemisphere. The survey comprises 8885 galaxies for which we have previously reported Fundamental Plane data. We obtain peculiar velocity probability distributions for the redshift-space positions of each of these galaxies using a Bayesian approach. Accounting for selection bias, we find that the logarithmic distance uncertainty is 0.11 dex, corresponding to 26 per cent in linear distance. We use adaptive kernel smoothing to map the observed 6dFGS velocity field out to cz ~ 16000 km s-1, and compare this to the predicted velocity fields from the PSCz Survey and the 2MASS Redshift Survey. We find a better fit to the PSCz prediction, although the reduced ¿2 for the whole sample is approximately unity for both comparisons. This means that, within the observational uncertainties due to redshift-independent distance errors, observed galaxy velocities and those predicted by the linear approximation from the density field agree. However, we find peculiar velocities that are systematically more positive than model predictions in the direction of the Shapley and Vela superclusters, and systematically more negative than model predictions in the direction of the Pisces-Cetus Supercluster, suggesting contributions from volumes not covered by the models.

We present a mid-infrared Tully-Fisher (TF) relation using photometry from the 3.4 µm W1 band of the Wide-field Infrared Survey Explorer (WISE) satellite. The WISE TF relation is formed from 568 galaxies taken from the all-sky 2MASS Tully-Fisher (2MTF) galaxy catalog, spanning a range of environments including field, group, and cluster galaxies. This constitutes the largest mid-infrared TF relation constructed to date. After applying a number of corrections to galaxy magnitudes and line widths, we measure a master TF relation given by M corr = -22.24-10.05[log (W corr)-2.5], with an average dispersion of sWISE = 0.686 mag. There is some tension between WISE TF and a preliminary 3.6 µm relation, which has a shallower slope and almost no intrinsic dispersion. However, our results agree well with a more recent relation constructed from a large sample of cluster galaxies. We additionally compare WISE TF to the near-infrared 2MTF template relations, finding a good agreement between the TF parameters and total dispersions of WISE TF and the 2MTF K-band template. This fact, coupled with typical galaxy colors of (K-W1) ~ 0, suggests that these two bands are tracing similar stellar populations, including the older, centrally-located stars in the galactic bulge which can (for galaxies with a prominent bulge) dominate the light profile. © 2013. The American Astronomical Society. All rights reserved..

We examine the hypothesis that mergers and close encounters between galaxies can fuel active galactic nuclei (AGNs) by increasing the rate at which gas accretes toward the central black hole. We compare the clustering of galaxies around radio-loud AGNs with the clustering around a population of radio-quiet galaxies with similar masses, colors, and luminosities. Our catalog contains 2178 elliptical radio galaxies with flux densities greater than 2.8 mJy at 1.4 GHz from the Six Degree Field Galaxy Survey. We find tentative evidence that radio AGNs with more than 200 times the median radio power have, on average, more close (r < 160 kpc) companions than their radio-quiet counterparts, suggesting that mergers play a role in forming the most powerful radio galaxies. For ellipticals of fixed stellar mass, the radio power is neither a function of large-scale environment nor halo mass, consistent with the radio powers of ellipticals varying by orders of magnitude over billions of years. © 2013. The American Astronomical Society. All rights reserved..

In this paper we study the stellar mass dependence of galaxy clustering in the 6dF Galaxy Survey (6dFGS). The near-infrared selection of 6dFGS allows more reliable stellar mass estimates compared to optical bands used in other galaxy surveys. Using the halo occupation distribution model, we investigate the trend of dark matter halo mass and satellite fraction with stellar mass by measuring the projected correlation function, wp(rp). We find that the typical halo mass (M1) as well as the satellite power-law index (a) increases with stellar mass. This indicates (1) that galaxies with higher stellar mass sit in more massive dark matter haloes and (2) that these more massive dark matter haloes accumulate satellites faster with growing mass compared to haloes occupied by low stellar mass galaxies. Furthermore, we find a relation between M1 and the minimum dark matter halo mass (Mmin) of M1 ¿ 22Mmin, in agreement with similar findings for Sloan Digital Sky Survey galaxies. The satellite fraction of 6dFGS galaxies declines with increasing stellar mass from 21 per cent at Mstellar=2.6×1010 h-2M¿ to 12 per cent at Mstellar=5.4 × 1010 h-2M¿ indicating that high stellar mass galaxies are more likely to be central galaxies. We compare our results to two different semi-analytic models derived from the Millennium Simulation, finding some disagreement. Our results can be used for placing new constraints on semi-analytic models in the future, particularly the behaviour of luminous red satellites. Finally, we compare our results to studies of halo occupation using galaxy-galaxy weak lensing. We find good overall agreement, representing a valuable cross-check for these two different tools of studying the matter distribution in the Universe. © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.

The Galaxy And Mass Assembly (GAMA) survey is a multiwavelength photometric and spectroscopic survey, using the AAOmega spectrograph on the Anglo-Australian Telescope to obtain spectra for up to ~300 000 galaxies over 280 deg2, to a limiting magnitude of rpet < 19.8 mag. The target galaxies are distributed over 0 < z ¿ 0.5 with a median redshift of z ¿ 0.2, although the redshift distribution includes a small number of systems, primarily quasars, at higher redshifts, up to and beyond z = 1. The redshift accuracy ranges from sv ¿ 50 km s-1 to sv ¿ 100 km s-1 depending on the signal-to-noise ratio of the spectrum. Here we describe the GAMA spectroscopic reduction and analysis pipeline. We present the steps involved in taking the raw two-dimensional spectroscopic images through to flux-calibrated one-dimensional spectra. The resulting GAMA spectra cover an observed wavelength range of 3750 ¿ 8850Å at a resolution of R ¿ 1300. The final flux calibration is typically accurate to 10-20 per cent, although the reliability is worse at the extreme wavelength ends, and poorer in the blue than the red. We present details of the measurement of emission and absorption features in the GAMA spectra. These measurements are characterized through a variety of quality control analyses detailing the robustness and reliability of the measurements. We illustrate the quality of the measurements with a brief exploration of elementary emission line properties of the galaxies in the GAMA sample. We demonstrate the luminosity dependence of the Balmer decrement, consistent with previously published results, and explore further how Balmer decrement varies with galaxy mass and redshift. We also investigate the mass and redshift dependencies of the [NII]/Ha versus [OIII]/Hß spectral diagnostic diagram, commonly used to discriminate between star forming and nuclear activity in galaxies. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

We present new wideband radio observations with the Australia Telescope Compact Array of a sample of 12 giant radio galaxies. The radio observations are part of a larger radio-optical study aimed at relating the radio structures with the ambient medium on large scales. With projected linear sizes larger than 0.7 Mpc, these objects are ideal candidates for the study of the warm-hot intergalactic medium (WHIM). The sample includes sources with sizes spanning 0.8-3.2 Mpc and total powers of 1.2 × 1024 to 4.0 × 1026 WHz-1 at 2.1 GHz. Redshifts were limited to z=0.15 to permit spectroscopic observations of the hosts and neighbouring galaxies, which were obtained using the AAOmega spectrograph on the Anglo-Australian Telescope. We derive lobe energy densities from the radio observations via equipartition arguments. The inferred pressures in the lobes of the giant radio sources,which range from 1.1×10-15 to 2.0× 10-14 Pa (80 to 1500 cm-3 K), are lower than previously inferred from X-ray observations of dense filaments. Comparison with the OverWhelmingly Large Simulations suggests that the WHIM in pressure balance with the radio lobes has a temperature in excess of ~106.5 K or a particle overdensity in the range 50-500. This study highlights the capability of next generation surveys, such as the Evolutionary Map of the Universe survey with the Australian Square Kilometre Array Pathfinder, to study populations of giant radio sources at lower surface brightness and thereby discriminate between models for the cosmological evolution of the intergalactic medium and examine the validity of cosmological hydrodynamical simulations. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

We present new 21-cm neutral hydrogen (H I) observations of spiral galaxies for the 2MASS Tully-Fisher (2MTF) survey. Using the 64-m Parkes radio telescope multibeam system we obtain 152 high signal-to-noise ratio H I spectra from which we extract 148 high-accuracy (<5 per cent error) velocity widths and derive reliable rotation velocities. The observed sample consists of 303 southern (d < -40°) galaxies selected from the 2MASS Redshift Survey with Ks < 11.25 mag, cz<10 000 km s-1 and axis ratio b/a<0.5. The H I observations reported in this paper will be combined with new H I spectra from the Green Bank and Arecibo telescopes, together producing the most uniform Tully-Fisher survey ever constructed (in terms of sky coverage). In particular, due to its near-infrared selection, 2MTF will be significantly more complete at low Galactic latitude (|b| < 15° and will provide a more reliable map of peculiar velocities in the local Universe. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Measurements of the low -z Ha luminosity function, f, have a large dispersion in the local number density of sources (~0.5-1 Mpc-3 dex-1), and correspondingly in the star formation rate density (SFRD). The possible causes for these discrepancies include limited volume sampling, biases arising from survey sample selection, different methods of correcting for dust obscuration and active galactic nucleus contamination. The Galaxy And Mass Assembly (GAMA) survey and Sloan Digital Sky Survey (SDSS) provide deep spectroscopic observations over a wide sky area enabling detection of a large sample of star-forming galaxies spanning 0.001 < SFRHa (M· yr-1) < 100 with which to robustly measure the evolution of the SFRD in the low-z Universe. The large number of high-SFR galaxies present in our sample allow an improved measurement of the bright end of the luminosity function, indicating that the decrease in f at bright luminosities is best described by a Saunders functional form rather than the traditional Schechter function. This result is consistent with other published luminosity functions in the far-infrared and radio. For GAMA and SDSS, we find the r-band apparent magnitude limit, combined with the subsequent requirement for Ha detection leads to an incompleteness due to missing bright Ha sources with faint r-band magnitudes. ©2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

WWe present evidence for stochastic star formation histories in low-mass (M* <1010M¿) galaxies from observations within the Galaxy And Mass Assembly (GAMA) survey. For ~73 000 galaxies between 0.05 < z < 0.32, we calculate star formation rates (SFR) and specific star formation rates (SSFR = SFR/M*) from spectroscopic Ha measurements and apply dust corrections derived from Balmer decrements. We find a dependence of SSFR on stellar mass, such that SSFRs decrease with increasing stellar mass for star-forming galaxies, and for the full sample, SSFRs decrease as a stronger function of stellar mass. We use simple parametrizations of exponentially declining star formation histories to investigate the dependence on stellar mass of the star formation time-scale and the formation redshift. We find that parametrizations previously fit to samples of z ~ 1 galaxies cannot recover the distributions of SSFRs and stellar masses observed in the GAMA sample between 0.05 < z <0.32. In particular, a large number of low-mass (M* < 1010M¿) galaxies are observed to have much higher SSFRs than can be explained by these simple models over the redshift range of 0.05 < z < 0.32, even when invoking mass-dependent staged evolution. For such a large number of galaxies to maintain low stellar masses, yet harbour such high SSFRs, requires the late onset of a weak underlying exponentially declining star formation history with stochastic bursts of star formation superimposed. ©2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

Structures of radio galaxies have the potential to reveal inconstancy in the axis of the beams, which reflect the stability in the spin axis of the supermassive black hole at the centre. We present radio observations of the giant radio galaxy B0707-359 whose structure offers an interesting case study of an active galactic nucleus (AGN) that may be exhibiting not only inconstancy in AGN output but also inconstancy in direction of ejection axis. Its radio morphology shows evidence for a restarting of the jets accompanied by an axis change. The observed side-to-side asymmetries of this giant radio galaxy suggest that the new jets are not in the plane of the sky. We infer that the hotspot advance velocities are unusually large and of magnitude a few tenths of the speed of light. The dual-frequency radio images are consistent with a model where the beams from the central engine ceased, creating a relic double radio source; this interruption was accompanied by triggering of a movement of the axis of the central engine at a rate of a few degrees Myr-1. The closer location of the giant radio galaxy axis to the host minor axis rather than the host major axis is supportive of the restarting and axis-change model for the formation of the double-double structure rather than the backflow model. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.

We have measured the clustering properties of low-redshift (z < 0.3) submm galaxies detected at 250 µm in the Herschel-ATLAS science demonstration phase field. We selected a sample for which we have high-quality spectroscopic redshifts, obtained from reliably matching the 250-µm sources to a complete (for r < 19.4) sample of galaxies from the GAMA data base. Both the angular and spatial clustering strength are measured for all z < 0.3 sources as well as for five redshift slices with thickness ¿z = 0.05 in the range 0.05 < z < 0.3. Our measured spatial clustering length r0 is comparable to that of optically selected, moderately star-forming (blue) galaxies: we find values around 5Mpc. One of the redshift bins contains an interesting structure, at z = 0.164. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

Context. The mass-metallicity relationship (MMR) of star-forming galaxies is well-established, however there is still some disagreement with respect to its exact shape and its possible dependence on other observables. Aims.We measure the MMR in the Galaxy And Mass Assembly (GAMA) survey. We compare our measured MMR to that measured in the Sloan Digital Sky Survey (SDSS) and study the dependence of the MMR on various selection criteria to identify potential causes for disparities seen in the literature. Methods.We use strong emission line ratio diagnostics to derive oxygen abundances. We then apply a range of selection criteria for the minimum signal-to-noise in various emission lines, as well as the apparent and absolute magnitude to study variations in the inferred MMR. Results. The shape and position of the MMR can differ significantly depending on the metallicity calibration and selection used. After selecting a robust metallicity calibration amongst those tested, we find that the mass-metallicity relation for redshifts 0.061 ¿ z ¿ 0.35 in GAMA is in reasonable agreement with that found in the SDSS despite the difference in the luminosity range probed. Conclusions. In view of the significant variations of the MMR brought about by reasonable changes in the sample selection criteria and method, we recommend that care be taken when comparing the MMR from different surveys and studies directly. We also conclude that there could be a modest level of evolution over 0.06 = z = 0.35 within the GAMA sample. © 2012 ESO.

We present the first scientific results from the Sydney-AAO Multi-Object IFS (SAMI) at the Anglo-Australian Telescope. This unique instrument deploys 13 fused fiber bundles (hexabundles) across a one-degree field of view allowing simultaneous spatially resolved spectroscopy of 13 galaxies. During the first SAMI commissioning run, targeting a single galaxy field, one object (ESO 185-G031) was found to have extended minor axis emission with ionization and kinematic properties consistent with a large-scale galactic wind. The importance of this result is twofold: (1) fiber bundle spectrographs are able to identify low surface brightness emission arising from extranuclear activity and (2) such activity may be more common than presently assumed because conventional multi-object spectrographs use single-aperture fibers and spectra from these are nearly always dominated by nuclear emission. These early results demonstrate the extraordinary potential of multi-object hexabundle spectroscopy in future galaxy surveys. © 2012. The American Astronomical Society. All rights reserved..

Galaxy and Mass Assembly (GAMA) is a project to study galaxy formation and evolution, combining imaging data from ultraviolet to radio with spectroscopic data from the AAOmega spectrograph on the Anglo-Australian Telescope. Using data from Phase 1 of GAMA, taken over three observing seasons, and correcting for various minor sources of incompleteness, we calculate galaxy luminosity functions (LFs) and their evolution in the ugriz passbands. At low redshift, z < 0.1, we find that blue galaxies, defined according to a magnitude-dependent but non-evolving colour cut, are reasonably well fitted over a range of more than 10 magnitudes by simple Schechter functions in all bands. Red galaxies, and the combined blue plus red sample, require double power-law Schechter functions to fit a dip in their LF faintwards of the characteristic magnitude M* before a steepening faint end. This upturn is at least partly due to dust-reddened disc galaxies. We measure the evolution of the galaxy LF over the redshift range 0.002 < z < 0.5 both by using a parametric fit and by measuring binned LFs in redshift slices. The characteristic luminosity L* is found to increase with redshift in all bands, with red galaxies showing stronger luminosity evolution than blue galaxies. The comoving number density of blue galaxies increases with redshift, while that of red galaxies decreases, consistent with prevailing movement from blue cloud to red sequence. As well as being more numerous at higher redshift, blue galaxies also dominate the overall luminosity density beyond redshifts z¿ 0.2. At lower redshifts, the luminosity density is dominated by red galaxies in the riz bands, and by blue galaxies in u and g. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

We use the Herschel-ATLAS survey to conduct the first large-scale statistical study of the submillimetre properties of optically selected galaxies. Using ~80000 r-band selected galaxies from 126 deg 2 of the GAMA survey, we stack into submillimetre imaging at 250, 350 and 500µ m to gain unprecedented statistics on the dust emission from galaxies at z < 0.35. We find that low-redshift galaxies account for 5 per cent of the cosmic 250-µm background (4 per cent at 350µ m; 3 per cent at 500µ m), of which approximately 60 per cent comes from 'blue' and 20 per cent from 'red' galaxies (rest-frame g-r). We compare the dust properties of different galaxy populations by dividing the sample into bins of optical luminosity, stellar mass, colour and redshift. In blue galaxies we find that dust temperature and luminosity correlate strongly with stellar mass at a fixed redshift, but red galaxies do not follow these correlations and overall have lower luminosities and temperatures. We make reasonable assumptions to account for the contaminating flux from lensing by red-sequence galaxies and conclude that galaxies with different optical colours have fundamentally different dust emission properties. Results indicate that while blue galaxies are more luminous than red galaxies due to higher temperatures, the dust masses of the two samples are relatively similar. Dust mass is shown to correlate with stellar mass, although the dust-to-stellar mass ratio is much higher for low stellar mass galaxies, consistent with the lowest mass galaxies having the highest specific star formation rates. We stack the 250µ m-to-NUV luminosity ratio, finding results consistent with greater obscuration of star formation at lower stellar mass and higher redshift. Submillimetre luminosities and dust masses of all galaxies are shown to evolve strongly with redshift, indicating a fall in the amount of obscured star formation in ordinary galaxies over the last four billion years. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

We demonstrate a novel technology that combines the power of the multi-object spectrograph with the spatial multiplex advantage of an integral field spectrograph (IFS). The Sydney-AAO (Australian Astronomical Observatory) Multi-object IFS (SAMI) is a prototype wide-field system at the Anglo-Australian Telescope (AAT) that allows 13 imaging fibre bundles ('hexabundles') to be deployed over a 1-degree diameter field of view. Each hexabundle comprises 61 lightly fused multi-mode fibres with reduced cladding and yields a 75 per cent filling factor. Each fibre core diameter subtends 1.6 arcsec on the sky and each hexabundle has a field of view of 15 arcsec diameter. The fibres are fed to the flexible AAOmega double-beam spectrograph, which can be used at a range of spectral resolutions (R=¿/d¿¿ 1700-13000) over the optical spectrum (3700-9500Å). We present the first spectroscopic results obtained with SAMI for a sample of galaxies at z¿ 0.05. We discuss the prospects of implementing hexabundles at a much higher multiplex over wider fields of view in order to carry out spatially resolved spectroscopic surveys of 10 4-10 5 galaxies. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

We present results from an analysis of stellar population parameters for 7132 galaxies in the 6dF Galaxy Survey Fundamental Plane (FP) sample. We bin the galaxies along the axes, v 1, v 2 and v 3, of the tri-variate Gaussian to which we have fitted the galaxy distribution in effective radius, surface brightness and central velocity dispersion (FP space), and compute median values of stellar age, [Fe/H], [Z/H] and [a/Fe]. We determine the directions of the vectors in FP space along which each of the binned stellar population parameters vary most strongly. In contrast to previous work, we find stellar population trends not just with velocity dispersion and FP residual, but with radius and surface brightness as well. The most remarkable finding is that the stellar population parameters vary through the plane (v 1 direction) and across the plane (v 3 direction), but show no variation at all along the plane (v 2 direction). The v 2 direction in FP space roughly corresponds to 'luminosity density'. We interpret a galaxy's position along this vector as being closely tied to its merger history, such that early-type galaxies with lower luminosity density are more likely to have undergone major mergers. This conclusion is reinforced by an examination of the simulations of Kobayashi, which show clear trends of merger history with v 2. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

We determine the low-redshift field galaxy stellar mass function (GSMF) using an area of 143deg 2 from the first three years of the Galaxy And Mass Assembly (GAMA) survey. The magnitude limits of this redshift survey are r < 19.4mag over two-thirds and 19.8mag over one-third of the area. The GSMF is determined from a sample of 5210 galaxies using a density-corrected maximum volume method. This efficiently overcomes the issue of fluctuations in the number density versus redshift. With H 0= 70kms -1Mpc -1, the GSMF is well described between 10 8 and 10 11.5M ¿ using a double Schechter function with M * = 10 10.66 M ¿, p 1* = 3.96 × 10 -3 Mpc -3, a 1=-0.35, p 2* = 0.79 × 10 -3 Mpc -3 and a 2=-1.47. This result is more robust to uncertainties in the flow-model corrected redshifts than from the shallower Sloan Digital Sky Survey main sample (r < 17.8mag). The upturn in the GSMF is also seen directly in the i-band and K-band galaxy luminosity functions. Accurately measuring the GSMF below 10 8M ¿ is possible within the GAMA survey volume but as expected requires deeper imaging data to address the contribution from low surface-brightness galaxies. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

We use deep Very Large Telescope (VLT) optical and near-infrared spectroscopy and deep Spitzer/IRAC imaging to examine the properties of two of the most luminous Lya emitters at z= 5.7. The continuum redward of the Lya line is clearly detected in both objects, thus facilitating a relatively accurate measurement (10-20per cent uncertainties) of the observed rest-frame equivalent widths, which are around 160Å for both objects. Through detailed modelling of the profile of the Lya line with a 3D Monte Carlo radiative transfer code, we estimate the intrinsic rest-frame equivalent width of Lya and find values that are around 300Å, which is at the upper end of the range allowed for very young, moderately metal-poor star-forming galaxies. However, the uncertainties are large and values as high as 700Å are permitted by the data. Both Lya emitters are detected at 3.6m in deep images taken with the Spitzer Space Telescope. We use these measurements, the measurement of the continuum redward of Lya and other photometry to constrain the spectral energy distributions of these very luminous Lya emitters and to compare them with three similar Lya emitters from the literature. The contribution from nebular emission is included in our models: excluding it results in significantly higher masses. Four of the five Lya emitters have masses of the order of ~10 9 M ¿ and fairly high specific star formation rates (¿10-100 Gyr -1). While our two Lya emitters appear similar in terms of the observed Lya rest-frame equivalent width, they are quite distinct from each other in terms of age, mass and star formation history. Evidence for dust is found in all objects, and emission from nebular lines often makes a dominant contribution to the rest-frame 3.6m flux. Rich in emission lines, these objects are prime targets for the next generation of extremely large telescopes, the James Webb Space Telescope (JWST) and the Atacama Large Millimeter Array (ALMA). © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

We present a detailed investigation into the effects of galaxy environment on their star formation rates (SFRs) using galaxies observed in the Galaxy And Mass Assembly (GAMA) survey. We use three independent volume-limited samples of galaxies within z < 0.2 and Mr < -17.8. We investigate the known SFR-density relationship and explore in detail the dependence of SFR on stellar mass and density. We show that the SFR-density trend is only visible when we include the passive galaxy population along with the star-forming population. This SFR-density relation is absent when we consider only the star-forming population of galaxies, consistent with previous work. While there is a strong dependence of the EWHa on density we find, as in previous studies, that these trends are largely due to the passive galaxy population and this relationship is absent when considering a 'star-forming' sample of galaxies. We find that stellar mass has the strongest influence on SFR and EWHa with the environment having no significant effect on the star formation properties of the star-forming population. We also show that the SFR-density relationship is absent for both early- and late-type star-forming galaxies. We conclude that the stellar mass has the largest impact on the current SFR of a galaxy, and any environmental effect is not detectable. The observation that the trends with density are due to the changing morphology fraction with density implies that the time-scales must be very short for any quenching of the SFR in infalling galaxies. Alternatively, galaxies may in fact undergo predominantly in situ evolution where the infall and quenching of galaxies from the field into dense environments is not the dominant evolutionary mode. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

We measure the two-point angular correlation function of a sample of 4289223 galaxies with r < 19.4mag from the Sloan Digital Sky Survey (SDSS) as a function of photometric redshift, absolute magnitude and colour down to Mr - 5logh = -14mag. Photometric redshifts are estimated from ugriz model magnitudes and two Petrosian radii using the artificial neural network package annz, taking advantage of the Galaxy And Mass Assembly (GAMA) spectroscopic sample as our training set. These photometric redshifts are then used to determine absolute magnitudes and colours. For all our samples, we estimate the underlying redshift and absolute magnitude distributions using Monte Carlo resampling. These redshift distributions are used in Limber's equation to obtain spatial correlation function parameters from power-law fits to the angular correlation function. We confirm an increase in clustering strength for sub-L red galaxies compared with ~L red galaxies at small scales in all redshift bins, whereas for the blue population the correlation length is almost independent of luminosity for ~L galaxies and fainter. A linear relation between relative bias and log luminosity is found to hold down to luminosities L ~ 0.03L. We find that the redshift dependence of the bias of the L population can be described by the passive evolution model of Tegmark & Peebles. A visual inspection of a random sample from our r < 19.4 sample of SDSS galaxies reveals that about 10per cent are spurious, with a higher contamination rate towards very faint absolute magnitudes due to over-deblended nearby galaxies. We correct for this contamination in our clustering analysis. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

We determine the near-infrared Fundamental Plane (FP) for ~104 early-type galaxies in the 6-degree Field Galaxy Survey (6dFGS). We fit the distribution of central velocity dispersion, near-infrared surface brightness and half-light radius with a 3D Gaussian model using a maximum-likelihood method. The model provides an excellent empirical fit to the observed FP distribution and the method proves robust and unbiased. Tests using simulations show that it gives superior results to regression techniques in the presence of significant and correlated uncertainties in all three parameters, censoring of the data by various selection effects and outliers in the data sample. For the 6dFGS J-band sample we find an FP with Re¿s01.52±0.03Ie-0.89±0.01, similar to previous near-infrared determinations and consistent with the H- and K-band FPs once allowance is made for differences in mean colour. The overall scatter in Re about the FP is sr = 29 per cent, and is the quadrature sum of an 18 per cent scatter due to observational errors and a 23 per cent intrinsic scatter. Because of the Gaussian distribution of galaxies in FP space, sr is not the distance error, which we find to be sd = 23 per cent. Using group richness and local density as measures of environment, and morphologies based on visual classifications, we find that the FP slopes do not vary with environment or morphology. However, for fixed velocity dispersion and surface brightness, field galaxies are on average 5 per cent larger than galaxies in groups or higher density environments, and the bulges of early-type spirals are on average 10 per cent larger than ellipticals and lenticulars. The residuals about the FP show significant trends with environment, morphology and stellar population. The strongest trend is with age, and we speculate that age is the most important systematic source of offsets from the FP, and may drive the other trends through its correlations with environment, morphology and metallicity. These results will inform our use of the near-infrared FP in deriving relative distances and peculiar velocities for 6dFGS galaxies. © 2012 The Authors Monthly Notices of the Royal Astronomical Society. © 2012 RAS.

We measure the projected cross-correlation between low-redshift (z < 0.5) far-infrared selected galaxies in the science demonstration phase (SDP) field of the Herschel-ATLAS (H-ATLAS) survey and optically selected galaxies from the Galaxy and Mass Assembly (GAMA) redshift survey. In order to obtain robust correlation functions, we restrict the analysis to a subset of 969 out of 6900 H-ATLAS galaxies, which have reliable optical counterparts with r < 19.4mag and well-determined spectroscopic redshifts. The overlap region between the two surveys is 12.6 deg2; the matched sample has a median redshift of z¿ 0.2. The cross-correlation of GAMA and H-ATLAS galaxies within this region can be fitted by a power law, with correlation length r0¿ 4.63 ± 0.51 Mpc. Comparing with the corresponding autocorrelation function of GAMA galaxies within the SDP field yields a relative bias (averaged over 2-8 Mpc) of H-ATLAS and GAMA galaxies of bH/bG¿ 0.6. Combined with clustering measurements from previous optical studies, this indicates that most of the low-redshift H-ATLAS sources are hosted by haloes with masses comparable to that of the Milky Way. The correlation function appears to depend on the 250-µm luminosity, L250, with bright (median luminosity ¿L250~ 1.6 × 1010L¿) objects being somewhat more strongly clustered than faint (¿L250~ 4.0 × 109L¿) objects. This implies that galaxies with higher dust-obscured star formation rates are hosted by more massive haloes. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

We present the burst ages for young stellar populations in a sample of six nearby (<10 Mpc) spiral galaxies using a differential pixel-based analysis of the ionized gas emission. We explore this as an alternative approach for connecting large-scale dynamical mechanisms with star formation processes in disc galaxies, based on burst ages derived from the Ha to far-UV (FUV) flux ratio. Images of each galaxy in Ha were taken with Taurus Tunable Filter and matched to FUV imaging from GALEX. The resulting flux ratio provides a robust measure of relative age across the disc which we discuss in terms of the large-scale dynamical motions. Systematic effects such as a variable initial mass function, non-solar metallicities, variable star formation histories (SFHs) and dust attenuation have been used to derive estimates of the systematic uncertainty. The resulting age maps show a wide range of patterns outside of those galaxies with the strongest spiral structure, confirming the idea that star formation is driven one by several processes, largely determined by the individual circumstances of the galaxy. Generally, grand design spirals such as M74, M100 and M51 exhibit age gradients across the main spiral arms, with the youngest star formation regions along the central and inner edges. Likewise, in the dominant star-forming complex of IC 2574 or the ring of M94, the most recent star formation is centrally confined to the regions of star formation activity. In M63 and M74 galaxy-wide trends emerge, contrary to the spiral structure in these galaxies, suggesting that spiral density waves are not the dominant driver in some cases. We argue that despite appearances, galaxy morphology is not an absolute discriminator of the SFH of an individual galaxy, nor of the processes triggering it. We conclude that Ha-to-FUV flux ratios are a relatively direct way to probe burst ages across galaxies and infer something of their dynamical histories, provided that sources of systematics are properly taken into account. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

We present a technique to identify optical counterparts of 250-µm-selected sources from theHerschel-ATLAS survey. Of the 6621 250µm > 32-mJy sources in our science demonstration catalogue we find that ~60 per cent have counterparts brighter thanr= 22.4mag in the Sloan Digital Sky Survey. Applying a likelihood ratio technique we are able to identify 2423 of the counterparts with a reliabilityR> 0.8. This is approximately 37 per cent of the full 250-µm catalogue. We have estimated photometric redshifts for each of these 2423 reliable counterparts, while 1099 also have spectroscopic redshifts collated from several different sources, including the GAMA survey. We estimate the completeness of identifying counterparts as a function of redshift, and present evidence that 250-µm-selectedHerschel-ATLAS galaxies have a bimodal redshift distribution. Those with reliable optical identifications have a redshift distribution peaking atz¿ 0.25 ± 0.05, while submillimetre colours suggest that a significant fraction with no counterpart above ther-band limit havez> 1. We also suggest a method for selecting populations of strongly lensed high-redshift galaxies. Our identifications are matched to UV-NIR photometry from the GAMA survey, and these data are available as part of theHerschel-ATLAS public data release. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

We present self-consistent star formation rates derived through pan-spectral analysis of galaxies drawn from the Galaxy and Mass Assembly (GAMA) survey. We determine the most appropriate form of dust obscuration correction via application of a range of extinction laws drawn from the literature as applied to Ha, [O ii] and UV luminosities. These corrections are applied to a sample of 31 508 galaxies from the GAMA survey at z < 0.35. We consider several different obscuration curves, including those of Milky Way, Calzetti and Fischera and Dopita curves and their effects on the observed luminosities. At the core of this technique is the observed Balmer decrement, and we provide a prescription to apply optimal obscuration corrections using the Balmer decrement. We carry out an analysis of the star formation history (SFH) using stellar population synthesis tools to investigate the evolutionary history of our sample of galaxies as well as to understand the effects of variation in the initial mass function (IMF) and the effects this has on the evolutionary history of galaxies. We find that the Fischera and Dopita obscuration curve with an Rv value of 4.5 gives the best agreement between the different SFR indicators. The 2200 Å feature needed to be removed from this curve to obtain complete consistency between all SFR indicators suggesting that this feature may not be common in the average integrated attenuation of galaxy emission. We also find that the UV dust obscuration is strongly dependent on the SFR. © 2010 The Authors. Journal compilation © 2010 RAS.

In order to generate credible 0.1-2µm spectral energy distributions, the Galaxy and Mass Assembly (GAMA) project requires many gigabytes of imaging data from a number of instruments to be reprocessed into a standard format. In this paper, we discuss the software infrastructure we use, and create self-consistent ugrizYJHK photometry for all sources within the GAMA sample. Using UKIDSS and SDSS archive data, we outline the pre-processing necessary to standardize all images to a common zero-point, the steps taken to correct for the seeing bias across the data set and the creation of gigapixel-scale mosaics of the three 4 × 12deg2 GAMA regions in each filter. From these mosaics, we extract source catalogues for the GAMA regions using elliptical Kron and Petrosian matched apertures. We also calculate Sérsic magnitudes for all galaxies within the GAMA sample using sigma, a galaxy component modelling wrapper for galfit 3. We compare the resultant photometry directly and also calculate the r-band galaxy luminosity function for all photometric data sets to highlight the uncertainty introduced by the photometric method. We find that (1) changing the object detection threshold has a minor effect on the best-fitting Schechter parameters of the overall population (M*plusmn; 0.055mag, a± 0.014, f{symbol}*± 0.0005h3Mpc-3); (2) there is an offset between data sets that use Kron or Petrosian photometry, regardless of the filter; (3) the decision to use circular or elliptical apertures causes an offset in M* of 0.20mag; (4) the best-fitting Schechter parameters from total-magnitude photometric systems (such as SDSS modelmag or Sérsic magnitudes) have a steeper faint-end slope than photometric systems based upon Kron or Petrosian measurements; and (5) our Universe's total luminosity density, when calculated using Kron or Petrosian r-band photometry, is underestimated by at least 15 per cent. © 2010 The Authors Monthly Notices of the Royal Astronomical Society © 2010 RAS.

The Galaxy and Mass Assembly (GAMA) survey has been operating since 2008 February on the 3.9-m Anglo-Australian Telescope using the AAOmega fibre-fed spectrograph facility to acquire spectra with a resolution ofR¿ 1300for 120862 Sloan Digital Sky Survey selected galaxies. The target catalogue constitutes three contiguous equatorial regions centred at 9h(G09), 12h(G12) and 14.5h(G15) each of12 × 4deg2to limiting fluxes ofrpet < 19.4, rpet < 19.8andrpet < 19.4mag, respectively (and additional limits at other wavelengths). Spectra and reliable redshifts have been acquired for over 98 per cent of the galaxies within these limits. Here we present the survey footprint, progression, data reduction, redshifting, re-redshifting, an assessment of data quality after 3 yr, additional image analysis products (includingugrizYJHKphotometry, Sérsic profiles and photometric redshifts), observing mask and construction of our core survey catalogue (GamaCore). From this we create three science-ready catalogues: GamaCoreDR1 for public release, which includes data acquired during year 1 of operations within specified magnitude limits (2008 February to April); GamaCoreMainSurvey containing all data above our survey limits for use by the GAMA Team and collaborators; and GamaCoreAtlasSV containing year 1, 2 and 3 data matched to Herschel-ATLAS science demonstration data. These catalogues along with the associated spectra, stamps and profiles can be accessed via the GAMA website: © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

We present an analysis of the properties of the lowest Ha-luminosity galaxies (LHa= 4 × 1032 W; SFR < 0.02 M¿yr-1, with SFR denoting the star formation rate) in the Galaxy And Mass Assembly survey. These galaxies make up the rise above a Schechter function in the number density of systems seen at the faint end of the Ha luminosity function. Above our flux limit, we find that these galaxies are principally composed of intrinsically low stellar mass systems (median stellar mass = 2.5 × 108M¿) with only 5/90 having stellar masses M > 1010M¿. The low-SFR systems are found to exist predominantly in the lowest-density environments (median density ~0.02galaxyMpc-2) with none in environments more dense than ~1.5galaxyMpc-2. Their current specific SFRs (SSFRs; -8.5 < log[SSFR (yr -1)] < -12) are consistent with their having had a variety of star formation histories. The low-density environments of these galaxies demonstrate that such low-mass, star-forming systems can only remain as low mass and form stars if they reside sufficiently far from other galaxies to avoid being accreted, dispersed through tidal effects or having their gas reservoirs rendered ineffective through external processes. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

The stellar initial mass function (IMF) describes the distribution in stellar masses produced from a burst of star formation. For more than 50 yr, the implicit assumption underpinning most areas of research involving the IMF has been that it is universal, regardless of time and environment. We measure the high-mass IMF slope for a sample of low-to-moderate redshift galaxies from the Galaxy and Mass Assembly survey. The large range in luminosities and galaxy masses of the sample permits the exploration of underlying IMF dependencies. A strong IMF-star formation rate dependency is discovered, which shows that highly star-forming galaxies form proportionally more massive stars (they have IMFs with flatter power-law slopes) than galaxies with low star formation rates. This has a significant impact on a wide variety of galaxy evolution studies, all of which rely on assumptions about the slope of the IMF. Our result is supported by, and provides an explanation for, the results of numerous recent explorations suggesting a variation of or evolution in the IMF. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

We use multiwavelength data from the Galaxy And Mass Assembly (GAMA) and Herschel-ATLAS (H-ATLAS) surveys to compare the relationship between various dust obscuration measures in galaxies. We explore the connections between the ultraviolet (UV) spectral slope, ß, the Balmer decrement and the far-infrared (FIR) to 150nm far-ultraviolet (FUV) luminosity ratio. We explore trends with galaxy mass, star formation rate (SFR) and redshift in order to identify possible systematics in these various measures. We reiterate the finding of other authors that there is a large scatter between the Balmer decrement and the ß parameter, and that ß may be poorly constrained when derived from only two broad passbands in the UV. We also emphasize that FUV-derived SFRs, corrected for dust obscuration using ß, will be overestimated unless a modified relation between ß and the attenuation factor is used. Even in the optimum case, the resulting SFRs have a significant scatter, well over an order of magnitude. While there is a stronger correlation between the IR-to-FUV luminosity ratio and ß parameter than with the Balmer decrement, neither of these correlations are particularly tight, and dust corrections based on ß for high-redshift galaxy SFRs must be treated with caution. We conclude with a description of the extent to which the different obscuration measures are consistent with each other as well as the effects of including other galactic properties on these correlations. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

We analyse the large-scale correlation function of the 6dF Galaxy Survey (6dFGS) and detect a baryon acoustic oscillation (BAO) signal at 105h-1Mpc. The 6dFGS BAO detection allows us to constrain the distance-redshift relation at zeff= 0.106. We achieve a distance measure of DV(zeff) = 457 ± 27Mpc and a measurement of the distance ratio, rs(zd)/DV(zeff) = 0.336 ± 0.015 (4.5 per cent precision), where rs(zd) is the sound horizon at the drag epoch zd. The low-effective redshift of 6dFGS makes it a competitive and independent alternative to Cepheids and low-z supernovae in constraining the Hubble constant. We find a Hubble constant of H0= 67 ± 3.2kms-1Mpc-1 (4.8 per cent precision) that depends only on the Wilkinson Microwave Anisotropy Probe-7 (WMAP-7) calibration of the sound horizon and on the galaxy clustering in 6dFGS. Compared to earlier BAO studies at higher redshift, our analysis is less dependent on other cosmological parameters. The sensitivity to H0 can be used to break the degeneracy between the dark energy equation of state parameter w and H0 in the cosmic microwave background data. We determine that w=-0.97 ± 0.13, using only WMAP-7 and BAO data from both 6dFGS and Percival et al. (2010). We also discuss predictions for the large-scale correlation function of two future wide-angle surveys: the Wide field ASKAP L-band Legacy All-sky Blind surveY (WALLABY) blind Hi survey (with the Australian Square Kilometre Array Pathfinder, ASKAP) and the proposed Transforming Astronomical Imaging surveys through Polychromatic Analysis of Nebulae (TAIPAN) all-southern-sky optical galaxy survey with the UK Schmidt Telescope. We find that both surveys are very likely to yield detections of the BAO peak, making WALLABY the first radio galaxy survey to do so. We also predict that TAIPAN has the potential to constrain the Hubble constant with 3 per cent precision. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

We investigate the properties of satellite galaxies that surround isolated hosts within the redshift range 0.01 < z < 0.15, using data taken as part of the Galaxy And Mass Assembly survey. Making use of isolation and satellite criteria that take into account stellar mass estimates, we find 3514 isolated galaxies of which 1426 host a total of 2998 satellites. Separating the red and blue populations of satellites and hosts, using colour-mass diagrams, we investigate the radial distribution of satellite galaxies and determine how the red fraction of satellites varies as a function of satellite mass, host mass and the projected distance from their host. Comparing the red fraction of satellites to a control sample of small neighbours at greater projected radii, we show that the increase in red fraction is primarily a function of host mass. The satellite red fraction is about 0.2 higher than the control sample for hosts with, while the red fractions show no difference for hosts with. For the satellites of more massive hosts, the red fraction also increases as a function of decreasing projected distance. Our results suggest that the likely main mechanism for the quenching of star formation in satellites hosted by isolated galaxies is strangulation. © 2011 The Authors. Monthly Notices of the Royal Astronomical Society © 2011 RAS.

We investigate the ultraviolet and optical properties and environment of low-redshift galaxies detected in the Herschel Astrophysical Terahertz Large Area Survey (H-ATLAS) science demonstration data. We use the Sloan Digital Sky Survey seventh release and the Galaxy And Mass Assembly data base to select galaxies with mag in the redshift range 0.02 =z= 0.2 and look for their submillimetre counterparts in H-ATLAS. Our results show that at low redshift, H-ATLAS detects mainly blue/star-forming galaxies with a minor contribution from red systems which are highly obscured by dust. In addition we find that the colour of a galaxy rather than the local density of its environment determines whether it is detectable by H-ATLAS. The average dust temperature of galaxies that are simultaneously detected by both PACS and SPIRE is 25 ± 4K, independent of environment. This analysis provides a glimpse of the potential of the H-ATLAS data to investigate the submillimetre properties of galaxies in the local universe. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

This paper describes the first catalogue of photometrically derived stellar mass estimates for intermediate-redshift (z < 0.65; median z= 0.2) galaxies in the Galaxy And Mass Assembly (GAMA) spectroscopic redshift survey. These masses, as well as the full set of ancillary stellar population parameters, will be made public as part of GAMA data release 2. Although the GAMA database does include near-infrared (NIR) photometry, we show that the quality of our stellar population synthesis fits is significantly poorer when these NIR data are included. Further, for a large fraction of galaxies, the stellar population parameters inferred from the optical-plus-NIR photometry are formally inconsistent with those inferred from the optical data alone. This may indicate problems in our stellar population library, or NIR data issues, or both; these issues will be addressed for future versions of the catalogue. For now, we have chosen to base our stellar mass estimates on optical photometry only. In light of our decision to ignore the available NIR data, we examine how well stellar mass can be constrained based on optical data alone. We use generic properties of stellar population synthesis models to demonstrate that restframe colour alone is in principle a very good estimator of stellar mass-to-light ratio, M*/Li. Further, we use the observed relation between restframe (g-i) and M*/Li for real GAMA galaxies to argue that, modulo uncertainties in the stellar evolution models themselves, (g-i) colour can in practice be used to estimate M*/Li to an accuracy of ¿0.1 dex (1s). This 'empirically calibrated' (g-i)-M*/Li relation offers a simple and transparent means for estimating galaxies' stellar masses based on minimal data, and so provides a solid basis for other surveys to compare their results to z¿0.4 measurements from GAMA. © 2011 The Authors Monthly Notices of the Royal Astronomical Society © 2011 RAS.

We have determined the luminosity function of 250 µm-selected galaxies detected in the ~14 deg2science demonstration region of the Herschel-ATLAS project out to a redshift of z = 0.5. Our findings very clearly show that the luminosity function evolves steadily out to this redshift. By selecting a sub-group of sources within a fixed luminosity interval where incompleteness effects are minimal, we have measured a smooth increase in the comoving 250 µm luminosity density out to z = 0.2 where it is 3.6+1.4-0.9times higher than the local value. © 2010 ESO.

We present colour-colour diagrams of detected sources in the Herschel-ATLAS science demonstration field from 100 to 500 µm using both PACS and SPIRE. We fit isothermal modified black bodies to the spectral energy distribution (SED) to extract the dust temperature of sources with counterparts in Galaxy And Mass Assembly (GAMA) or SDSS surveys with either a spectroscopic or a photometric redshift. For a subsample of 330 sources detected in at least three FIR bands with a significance greater than 3s, we find an average dust temperature of (28±8) K. For sources with no known redshift, we populate the colour-colour diagram with a large number of SEDs generated with a broad range of dust temperatures and emissivity parameters, and compare to colours of observed sources to establish the redshift distribution of this sample. For another subsample of 1686 sources with fluxes above 35 mJy at 350 µm and detected at 250 and 500 µm with a significance greater than 3s, we find an average redshift of 2.2±0.6. © 2010 ESO.

We describe the spectroscopic target selection for the Galaxy And Mass Assembly (GAMA) survey. The input catalogue is drawn from the Sloan Digital Sky Survey (SDSS) and UKIRT Infrared Deep Sky Survey (UKIDSS). The initial aim is to measure redshifts for galaxies in three 4° × 12° regions at 9, 12 and 14.5 h, on the celestial equator, with magnitude selections r<19.4, z<18.2 and KAB < 17.6 over all three regions, and r<19.8 in the 12-h region. The target density is 1080 deg-2 in the 12-h region and 720 deg-2 in the other regions. The average GAMA target density and area are compared with completed and ongoing galaxy redshift surveys. The GAMA survey implements a highly complete star-galaxy separation that jointly uses an intensity-profile separator (¿sg = rpsf - rmodel as per the SDSS) and a colour separator. The colour separator is defined as ¿sg,jk = J - K - f (g - i), where f (g - i) is a quadratic fit to the J - K colour of the stellar locus over the range 0.3 <g- i<2.3. All galaxy populations investigated are well separated with ¿sg,jk > 0.2. From 2 yr out of a 3-yr AAOmega program on the Anglo-Australian Telescope, we have obtained 79 599 unique galaxy redshifts. Previously known redshifts in the GAMA region bring the total up to 98 497. The median galaxy redshift is 0.2 with 99 per cent at z<0.5. We present some of the global statistical properties of the survey, including K-band galaxy counts, colour-redshift relations and preliminary n(z). © 2010 The Authors. Journal compilation. © 2010 RAS.

We use data from the Herschel-ATLAS to investigate the evolution of the far-infrared-radio correlation over the redshift range 0 < z < 0.5. Using the total far-infrared luminosity of all >5s sources in the Herschel-ATLAS Science Demonstration Field and cross-matching these data with radio data from the Faint Images of the Radio Sky at Twenty-Centimetres (FIRST) survey and the NRAO Very Large Array (VLA) Northern Sky Survey (NVSS), we obtain 104 radio counterparts to the Herschel sources. With these data we find no evidence for evolution in the far-infrared-radio correlation over the redshift range 0 < z < 0.5, where the median value for the ratio between far-infrared and radio luminosity, qIR, over this range is qIR= 2.40 ± 0.12 (and a mean of qIR= 2.52 ± 0.03 accounting for the lower limits), consistent with both the local value determined from IRAS and values derived from surveys targeting the high-redshift Universe. By comparing the radio fluxes of our sample measured from both FIRST and NVSS we show that previous results suggesting an increase in the value of qIR from high to low redshift may be the result of resolving out extended emission of the low-redshift sources with relatively high-resolution interferometric data, although contamination from active galactic nuclei could still play a significant role.We also find tentative evidence that the longer wavelength cooler dust is heated by an evolved stellar population which does not trace the star formation rate as closely as the shorter wavelength ¿ 250µm emission or the radio emission, supporting suggestions based on detailed models of individual galaxies. © 2010 The Authors. Journal compilation © 2010 RAS.

We use the Herschel-Astrophysical Terahertz Large Area Survey (ATLAS) science demonstration data to investigate the star formation properties of radio-selected galaxies in the GAMA-9h field as a function of radio luminosity and redshift. Radio selection at the lowest radio luminosities, as expected, selects mostly starburst galaxies. At higher radio luminosities, where the population is dominated by active galactic nuclei (AGN), we find that some individual objects are associated with high far-infrared luminosities. However, the far-infrared properties of the radio-loud population are statistically indistinguishable from those of a comparison population of radio-quiet galaxies matched in redshift and K-band absolute magnitude. There is thus no evidence that the host galaxies of these largely low-luminosity (Fanaroff-Riley class I), and presumably low-excitation, AGN, as a population, have particularly unusual star formation histories. Models in which the AGN activity in higher luminosity, high-excitation radio galaxies is triggered by major mergers would predict a luminosity-dependent effect that is not seen in our data (which only span a limited range in radio luminosity) but which may well be detectable with the full Herschel-ATLAS data set. © 2010 The Authors. Journal compilation © 2010 RAS.

A heuristic greedy algorithm is developed for efficiently tiling spatially dense redshift surveys. In its first application to the Galaxy and Mass Assembly (GAMA) redshift survey we find it rapidly improves the spatial uniformity of our data, and naturally corrects for any spatial bias introduced by the 2dF multi-object spectrograph. We make conservative predictions for the final state of the GAMA redshift survey after our final allocation of time, and can be confident that even if worse than typical weather affects our observations, all of our main survey requirements will be met. © 2010 Astronomical Society of Australia.

The Two Micron All-Sky Survey (2MASS) has provided a uniform photometric catalog to search for previously unknown red active galactic nuclei (AGN) and Quasi-Stellar Objects (QSOs). We have extended the search to the southern equatorial sky by obtaining spectra for 1182 AGN candidates using the six degree field (6dF) multifibre spectrograph on the UK Schmidt Telescope. These were scheduled as auxiliary targets for the 6dF Galaxy Redshift Survey. The candidates were selected using a single color cut of J-Ks > 2 to Ks ¿ 15.5 and a galactic latitude of |b|> 30°. 432 spectra were of sufficient quality to enable a reliable classification. 116 sources (~27%) were securely classified as type I AGN, 20 as probable type I AGN, and 57 as probable type II AGN. Most of them span the redshift range 0.05 < z < 0.5 and only 8 (~6%) were previously identified as AGN or QSOs. Our selection leads to a significantly higher AGN identification rate amongst local galaxies (>20%) than in any previous (mostly blue-selected) galaxy survey. A small fraction of the type I AGN could have their optical colors reddened by optically thin dust with AV < 2mag relative to optically selected QSOs. A handful show evidence of excess far-infrared (IR) emission. The equivalent width (EW) and color distributions of the type I and II AGN are consistent with AGN unified models. In particular, the EW of the [Oiii] emission line weakly correlates with opticalnear-IR color in each class of AGN, suggesting anisotropic obscuration of the AGN continuum. Overall, the optical properties of the 2MASS red AGN are not dramatically different from those of optically-selected QSOs. Our near-IR selection appears to detect the most near-IR luminous QSOs in the local universe to z¿0.6 and provides incentive to extend the search to deeper near-IR surveys. © Astronomical Society of Australia 2010.

We report the final redshift release of the 6dF Galaxy Survey (6dFGS), a combined redshift and peculiar velocity survey over the southern sky (|b| > 10°). Its 136 304 spectra have yielded 110 256 new extragalactic redshifts and a new catalogue of 125 071 galaxies making near-complete samples with (K, H, J, rF, bJ) = (12.65, 12.95, 13.75, 15.60, 16.75). The median redshift of the survey is 0.053. Survey data, including images, spectra, photometry and redshifts, are available through an online data base. We describe changes to the information in the data base since earlier interim data releases. Future releases will include velocity dispersions, distances and peculiar velocities for the brightest early-type galaxies, comprising about 10 per cent of the sample. Here we provide redshift maps of the southern local Universe with z = 0.1, showing nearby large-scale structures in hitherto unseen detail. A number of regions known previously to have a paucity of galaxies are confirmed as significantly underdense regions. The URL of the 6dFGS data base is http://www-wfau.roe.ac.uk/6dFGS. © 2009 RAS.

We use narrow-band imaging (full width at half-maximum = 70 Å) to select a sample of emission-line galaxies between 0.20 ¿ z ¿ 1.22 in two fields covering 0.5 deg2. We use spectroscopic follow-up to select a subsample of Ha-emitting galaxies at z ~ 0.24 and determine the Ha luminosity function and star formation density at z ~ 0.24 for both of our fields. Corrections are made for imaging and spectroscopic incompleteness, extinction and interloper contamination on the basis of the spectroscopic data. When compared to each other, we find the field samples differ by ¿a = 0.2 in faint-end slope and ¿log [L* (erg s-1)] = 0.2 in luminosity. In the context of other recent surveys, our sample has comparable faint-end slope, but a fainter L* turnover. We conclude that systematic uncertainties and differences in selection criteria remain the dominant sources of uncertainty between Ha luminosity functions at this redshift. We also investigate average star formation rates as a function of local environment and find typical values consistent with the field densities that we probe, in agreement with previous results. However, we find tentative evidence for an increase in star formation rate with respect to the local density of star-forming galaxies, consistent with the scenario that galaxy-galaxy interactions are triggers for bursts of star formation. © 2007 The Authors.

Context. Wide-field narrowband surveys are an efficient way of searching large volumes of high-redshift space for distant galaxies. Aims. We describe the Wide Field Imager Lyman-Alpha Search (WFILAS) over 0.74 sq. degree for bright emission-line galaxies at z ~ 5.7. Methods. WFILAS uses deep images taken with the Wide Field Imager (WFI) on the ESO/MPI 2.2 m telescope in three narrowband (70 Å), one encompassing intermediate band (220 Å) and two broadband filters, B and R. We use the novel technique of an encompassing intermediate band filter to exclude false detections. Images taken with broadband B and R filters are used to remove low redshift galaxies from our sample. Results. We present a sample of seven Lya emitting galaxy candidates, two of which are spectroscopically confirmed. Compared to other surveys all our candidates are bright, the results of this survey complements other narrowband surveys at this redshift. Most of our candidates are in the regime of bright luminosities, beyond the reach of less voluminous surveys. Adding our candidates to those of another survey increases the derived luminosity density by ~30%. We also find potential clustering in the Chandra Deep Field South, supporting overdensities discovered by other surveys. Based on a FORS2/VLT spectrum we additionally present the analysis of the second confirmed Lya emitting galaxy in our sample. We find that it is the brightest Lya emitting galaxy (1 × 10-16 erg s -1 cm-2) at this redshift to date and the second confirmed candidate of our survey. Both objects exhibit the presence of a possible second Lya component redward of the line. © ESO 2006.

Luminosity functions and their integrated luminosity densities are presented for the 6-degree Field Galaxy Survey (6dFGS). This ongoing survey ultimately aims to measure around 150 000 redshifts and 15 000 peculiar velocities over almost the entire southern sky at. The main target samples are taken from the 2-Micron All-Sky Survey (2MASS) Extended Source Catalog and the SuperCOSMOS Sky Survey catalogue, and comprise 138 226 galaxies complete to (, 13.00, 13.75, 15.60, 16.75). These samples are comparable in size to the optically selected Sloan Digital Sky Survey and 2-degree Field Galaxy Redshift Survey (2dFGRS) samples, and improve on recent near-infrared-selected redshift surveys by more than an order of magnitude in both number and sky coverage. The partial samples used in this paper contain a little over half of the total sample in each band and are ~90 per cent complete. Luminosity distributions are derived using the, Sandage-Tammann-Yahil (STY) and step-wise maximum likelihood (SWML) estimators, and probe 1-2 absolute magnitudes fainter in the near-infrared than previous surveys. The effects of magnitude errors, redshift incompleteness and peculiar velocities have been taken into account and corrected throughout. Generally, the 6dFGS luminosity functions are in excellent agreement with those of similarly sized surveys. Our data are of sufficient quality to demonstrate that a Schechter function is not an ideal fit to the true luminosity distribution, due to its inability to simultaneously match the faint-end slope and rapid bright-end decline. Integrated luminosity densities from the 6dFGS are consistent with an old stellar population and moderately declining star formation rate. © 2006 RAS.

We estimate the acceleration on the Local Group (LG) from the 2 Micron All-Sky Redshift Survey (2MRS). The sample used includes about 23 200 galaxies with extinction-corrected magnitudes brighter than and it allows us to calculate the flux-weighted dipole. The near-infrared flux-weighted dipoles are very robust because they closely approximate a mass-weighted dipole, bypassing the effects of redshift distortions and require no preferred reference frame. This is combined with the redshift information to determine the change in dipole with distance. The misalignment angle between the LG and the cosmic microwave background (CMB) dipole drops to at around , but then increases at larger distances, reaching at around . Exclusion of the galaxies Maffei 1, Maffei 2, Dwingeloo 1, IC342 and M87 brings the resultant flux dipole to away from the CMB velocity dipole. In both cases, the dipole seemingly converges by . Assuming convergence, the comparison of the 2MRS flux dipole and the CMB dipole provides a value for the combination of the mass density and luminosity bias parameters. © 2006 RAS.

We present the reconstructed real-space density and the predicted velocity fields from the Two-Micron All-Sky Redshift Survey (2MRS). The 2MRS is the densest all-sky redshift survey to date and includes about 23 200 galaxies with extinction-corrected magnitudes brighter than Ks = 11.25. Our method is based on the expansion of these fields in Fourier-Bessel functions. Within this framework, the linear redshift distortions only affect the density field in the radial direction and can easily be deconvolved using a distortion matrix. Moreover, in this coordinate system, the velocity field is related to the density field by a simple linear transformation. The shot noise errors in the reconstructions are suppressed by means of a Wiener filter which yields a minimum variance estimate of the density and velocity fields. Using the reconstructed real-space density fields, we identify all major superclusters and voids. At 50 h-1 Mpc, our reconstructed velocity field indicates a backside infall to the Great Attractor region of vinfall = (491 ± 200) (ß/0.5)kms-1 in the Local Group frame and v infall = (64 ± 205) (ß/0.5)kms-1 in the cosmic microwave background (CMB) frame and ß is the redshift distortion parameter. The direction of the reconstructed dipole agrees well with the dipole derived by Erdogdu et al. The misalignment between the reconstructed 2MRS and the CMB dipoles drops to 13° at around 5000 km s-1 but then increases at larger distances. © 2006 RAS.

We report the spectroscopic confirmation of a compact Lya emitting galaxy at z = 5.721. A FORS2 spectrum of the source shows a strong asymmetric line with a flux of 5 × 10-17 erg s-1 cm -2, making it one of the brightest Lya emitting galaxies at this redshift, and a line-of-sight velocity dispersion of 400 km s -1. We also have a tentative detection of a second, narrower component that is redshifted by 400 km s-1 with respect to the main peak. A FORS2 image shows that the source is compact, with a FWHM of 0¿.75, which corresponds to 3.2 kpc at this redshift**. This source is a brighter example of J1236.8+6215 (Dawson et al. 2002, ApJ, 570, 92), another Lya emitting galaxy at z ~ 5.2.

We report the discovery of a faint Ha pulsar wind nebula (PWN) powered by the radio pulsar B0740-28. The characteristic bow-shock morphology of the PWN implies a direction of motion consistent with the previously measured velocity vector for the pulsar. The PWN has a flux density more than an order of magnitude lower than for the PWNe seen around other pulsars, but, for a distance 2 kpc, it is consistent with propagation through a medium of atomic density nH ~ 0.25 cm-3, and neutral fraction of 1%. The morphology of the PWN in the area close to the pulsar is distinct from that in downstream regions, as is also seen for the PWN powered by PSR B2224+65. In particular, the PWN associated with PSR B0740-28 appears to close at its rear, suggesting that the pulsar has recently passed through a transition from low density to high density ambient gas. The faintness of this source underscores that deep searches are needed to find further examples of optical pulsar nebulae.

We report the discovery of an Ha-emitting bow shock nebula powered by the nearby millisecond pulsar J2124-3358. The bow shock is very broad and is highly asymmetric about the pulsar's velocity vector. This shape is not consistent with that expected for the case of an isotropic wind interacting with a homogeneous ambient medium. Models that invoke an anisotropy in the pulsar wind, a bulk flow of the surrounding gas, or a density gradient in the ambient medium either perpendicular or parallel to the pulsar's direction of motion also fail to reproduce the observed morphology. However, we find an ensemble of good fits to the nebular morphology when we consider a combination of these effects. In all such cases, we find that the pulsar is propagating through an ambient medium of mean density 0.8-1.3 cm-3 and bulk flow velocity ~15-25 km s-1 and that the star has recently encountered an increase in density by 1-10 cm-3 over a scale ¿0.02 pc. The wide variety of models that fit the data demonstrate that in general there is no unique set of parameters that can be inferred from the morphology of a bow shock nebula.

The past 5 years have seen a rapid rise in the use of tunable filters in many diverse fields of astronomy, through Taurus Tunable Filter (TTF) instruments at the Anglo-Australian and William Herschel Telescopes. Over this time we have continually refined aspects of operation and developed a collection of special techniques to handle the data produced by these novel imaging instruments. In this paper, we review calibration procedures and summarize the theoretical basis for Fabry-Perot photometry that is central to effective tunable imaging. Specific mention is made of object detection and classification from deep narrow-band surveys containing several hundred objects per field. We also discuss methods for recognizing and dealing with artefacts (scattered light, atmospheric effects, etc.), which can seriously compromise the photometric integrity of the data if left untreated. Attention is paid to the different families of ghost reflections encountered, and the strategies used to minimize their presence. In our closing remarks, future directions for tunable imaging are outlined and contrasted with the Fabry-Perot technology employed in the current generation of tunable imagers.

Recent evidence suggests a decline in the volume-averaged star formation rate (SFR) with the advance of cosmic time since z ~ 1. It is not clear, however, the extent to which the selection of such samples influences the measurement of this quantity. Using the Taurus Tunable Filter (TTF) we have obtained an emission-line sample of faint star-forming galaxies over comparable look-back times: the TTF Field Galaxy Survey. By selecting through emission lines, we are screening galaxies through a quantity that scales directly with star formation activity for a given choice of initial mass function. The scanning narrowband technique furnishes a galaxy sample that differs from traditional broadband-selected surveys in both its volume-limited nature and selection of galaxies through emission-line flux. Three discrete wavelength intervals are covered, centered at Ha redshifts z = 0.08, 0.24, and 0.39. Galaxy characteristics are presented and comparisons made with existing surveys of both broadband and emission-line selection. Little overlap is found in a direct comparison between the TTF Field Galaxy Survey and a traditional galaxy redshift survey, as a result of the respective volume and flux limitations of each. When the number counts of emission-line objects are compared with those expected on the basis of existing Ha surveys, we find an excess of ~3 times at the faintest limits. While these detections are yet to be confirmed independently, inspection of the stronger subsample of galaxies detected in both the line and continuum (line-on-continuum subsample; 13%) is sufficient to support an excess population. The faintest objects are galaxies with little or no continuum, rendering them undetectable by conventional redshift surveys. This increase in the emission-line field population implies higher star formation densities over z ¿ 0.4. However, further study in the form of multiobject spectroscopic follow-up is necessary to quantify this and confirm the faintest detections in the sample.

Tunable narrowband emission line surveys have begun to show the ease with which star-forming galaxies can be identified in restricted redshift intervals to z ~ 5 with a 4 m class telescope. These surveys have been carried out with imaging systems at the Cassegrain or Nasmyth focus, and are therefore restricted to fields smaller than 10'. We now show that tunable narrowband imaging is possible over a 30' field with a high-performance Lyot filter placed directly in front of a CCD mosaic at the prime focus. Our design is intended for the f/3.3 prime focus of the Anglo-Australian Telescope (AAT) 3.9 m, although similar devices can be envisaged for the Subaru 8 m (f/2), Palomar 5 m (f/3.4), Visible and Infrared Survey Telescope for Astronomy (VISTA) 4 m (f/6), Mayall 4 m (f/2.6), or the Canada-France-Hawaii Telescope (CFHT) 3.6 m (f/4). A modified Wynne doublet ensures subarcsecond performance over the field. In combination with the new Wide-Field Imager 8k × 8k mosaic (WFI) at the AAT, the overall throughput (35%) of the system to unpolarized light is expected to be comparable to the TAURUS Tunable Filter (TTF). Unlike the TTF, the field is fully monochromatic, and the instrumental profile has much better wing suppression. For targeted surveys of emission line sources at z ~ 1, a low-resolution (R ~ 150 at 550 nm) Lyot filter on a 4 m telescope is expected to be comparable or superior to current instruments on 8-10 m class telescopes. We demonstrate that the 30' field is well matched to superclusters at these redshifts, such that large-scale structure should be directly observable.

Supernova 1998bw holds the record for the most energetic Type Ic explosion, one of the brightest radio supernovae and probably the first supernova associated with a ¿-ray burst. In this paper we present spectral observations of SN 1998bw observed in a cooperative monitoring campaign using the Anglo-Australian Telescope, the UK Schmidt Telescope and the Siding Springs Observatories 2.3-m telescope. We investigate the evolution of the spectrum between 7 and 94 d after V-band maximum in comparison with well-studied examples of Type Ic SNe in order to quantify the unusual properties of this supernova event. Though the early spectra differ greatly from observations of classical Ic supernovae (SNe), we find that the evolution from the photospheric to nebular phases is slow but otherwise typical. The spectra differ predominantly in the extensive line blending and blanketing which has been attributed to the high velocity of the ejecta. We find that by day 19, the absorption line minima blueshifts are 10-50 per cent higher than other SNe and on day 94 emission lines are 45 per cent broader, as expected if the progenitor had a massive envelope. However, it is difficult to explain the extent of line blanketing entirely by line broadening, and we argue that an additional contribution from other species is present, indicating unusual relative abundances or physical conditions in the envelope.

We describe a method to quantify the degree of parallelism between two transparent glass mirrors spaced a few microns apart. Our technique, which permits the measurement and correction of deviations as small as ¿/10000 from parallelism, is fundamental to the successful operation of tunable narrowband interference filters for two reasons. First, the highest throughput is achieved when the plates are parallel at any plate spacing. Second, the lowest resolution (largest bandpass) imaging is achieved when the plates are only a few microns apart, but there is a real danger of the plates touching if parallelism is not maintained. The Taurus Tunable Filter (TTF)3 is a Fabry-Perot cavity with an adjustable plate spacing of 2-13 µm. The parallelism measurement involves repeated imaging through a local-plane slit and a series of pupil-plane masks. This approach is particularly efficient when the plate scanning is synchronized with the movement of the charge on the CCD. We assess the effects of wavelength-dependent phase changes within the inner surface coatings of the plates. These become important as the plates approach a spacing comparable in size to the thickness of the coatings.

The Taurus Tunable Filter (TTF) is a tunable narrowband interference filter covering wavelengths from 6300 A to the sensitivity drop-off of conventional CCDs (~9600 Å), although a blue 'arm' (4000-6500 Å) is to be added by the end of 1997. The TTF offers monochromatic imaging at the Cassegrain foci of both the Anglo-Australian and William Herschel Telescopes, with an adjustable passband of between 6 and 60 A. In addition, frequency switching with the TTF can be synchronised with movement of charge (charge shuffling) on the CCD, which has important applications to many astrophysical problems. Here we review the different modes of TTF and suggest their use for follow-up narrowband imaging to the AAO/UKST Galactic Plane Ha Survey.

While recent years have seen rapid growth in the number of galaxy peculiar velocity measurements, disagreements remain about the extent to which the peculiar velocity field - a tracer of the large-scale distribution of mass - agrees with both ¿CDM expectations and with velocity field models derived from redshift surveys. The 6dF Galaxy Survey includes peculiar velocities for nearly 9 000 early-type galaxies (6dFGSv), making it the largest and most homogeneous galaxy peculiar velocity sample to date. We have used the 6dFGS velocity field to determine the amplitude and scale of large-scale cosmic flows in the local universe and test standard cosmological models. We also compare the galaxy density and peculiar velocity fields to establish the distribution of dark and luminous matter and better constrain key cosmological parameters such as the redshift-space distortion parameter.

We have measured Fundamental Plane (FP) parameters in the 2MASS J, H and K passbands for 10,000 ellipticals, lenticulars and early-type spiral bulges in the 6dF Galaxy Survey (6dFGS) - a spectroscopic survey of the southern sky with |b| > 10° (Jones et al. 2009). 6dFGS provides a large near-infrared-selected sample of galaxies for accurately determining the NIR FP and investigating the trends in the FP with stellar population, morphology and environment. © 2013 International Astronomical Union.

SAMI (Sydney-AAO Multi-object Integral field spectrograph) has the potential to revolutionise our understanding of galaxies, with spatially-resolved spectroscopy of large numbers of targets. It is the first on-sky application of innovative photonic imaging bundles called hexabundles, which will remove the aperture effects that have biased previous single-fibre multi-object astronomical surveys. The hexabundles have lightly-fused circular multi-mode cores with a covering fraction of ~ 73%. The thirteen hexabundles in SAMI, each have 61 fibre cores, and feed into the AAOmega spectrograph at the Anglo-Australian Telescope (AAT). SAMI was installed at the AAT in July 2011 and the first commissioning results prove the effectiveness of hexabundles on sky. A galaxy survey of several thousand galaxies to z ~ 0.1 will begin with SAMI in mid-2012. © 2012 SPIE.

We have used over 10,000 early-type galaxies from the 6dF Galaxy Survey (6dFGS) to construct the Fundamental Plane across the optical and near-infrared passbands. We demonstrate that a maximum likelihood fit to a multivariate Gaussian model for the distribution of galaxies in size, surface brightness and velocity dispersion can properly account for selection effects, censoring and observational errors, leading to precise and unbiased parameters for the Fundamental Plane and its intrinsic scatter. This method allows an accurate and robust determination of the dependencies of the Fundamental Plane on variations in the stellar populations and environment of early-type galaxies. © International Astronomical Union 2010.

The 6dF Galaxy Survey provides a very large sample of galaxies with reliable measurements of Lick line indices and velocity dispersions. This sample can be used to explore the correlations between mass and stellar population parameters such as age, metallicity and [/Fe]. Preliminary results from such an analysis are presented here, and show that age and metallicity are significantly anti-correlated for both passive and star-forming galaxies. Passive galaxies have strong correlations between mass and metallicity and between age and -element over-abundance, which combine to produce a downsizing relation between age and mass. For old passive galaxies, the different trends of M/L with mass and luminosity in different passbands result from the differential effect of the massmetallicity relation on the luminosities in each passband. Future work with this sample will examine the Fundamental Plane of bulge-dominated galaxies and the influence of environment on relations between stellar population parameters and mass. © 2008 International Astronomical Union.

OTELO, (OSIRIS Tunable Emission Line Object Survey), will survey emission line objects using OSIRIS tunable filters in selected atmospheric windows relatively free of sky emission lines. Different high latitude and low extinction sky regions with enough angular separations will be observed yielding a total area of 1{2 square degrees. A 5 depth of 8×10 -18 erg/cm2/s will allow detecting objects of EW-6, making OTELO the deepest emission line survey to date. OTELO is a deep space probe that will provide a representative sample of the Universe from z =0.24 through 6.7. Given the observing procedure, OTELO will allow studying clearly de fined volumes of Universe at a known ux limit. In this contribution, a review of the project status is presented,together with some of the most significant evolutionary studies that will be tackled. © 2005: Instituto de Astronomía, UNAM.

The 6dF Galaxy Survey is measuring around 150 000 redshifts and 15 000 peculiar velocities from galaxies over the southern sky at |b| > 10°. When complete, it will be the largest survey of its kind by more than an order of magnitude. Here we describe the characteristics of the Second Incremental Data Release and provide an update of the survey. This follows earlier data made public in 2002 December and 2004 March. A total of 83 014 sources now have their spectra, redshifts, and near-infrared and optical photometry available online and searchable through an Structured Query Language database at www-wfau.roe.ac.uk/6dFGS/. © Astronomical Society of Australia 2005.

The Taurus Tunable Filter (TTF) is a pair of tunable narrowband interference filters covering 3700-6500 Å (blue 'arm') and 6500-9600 Å (red 'arm'). The TTF offers monochromatic imaging at the cassegrain foci of both the Anglo-Australian and William Herschel Telescopes, with an adjustable passband of between 6 and 60 Å. In addition, frequency switching with the TTF can be synchronized with movement of charge (charge shuffling) on the CCD which has important applications to many astrophysical problems. Here we review the different modes of TTF and suggest their use for narrowband imaging.