No abstract

The definitive version can be found at: http://onlinelibrary.wiley.com/ Copyright Royal Astronomical SocietyThe 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 of R approximate to 1300 for 120 862 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 of 12 x 4 deg2 to limiting fluxes of r(pet) < 19.4, r(pet) < 19.8 and r(pet) < 19.4 mag, 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 (including ugrizYJHK photometry, Sersic 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: http://www.gama-survey.org/

We present in this paper a detailed analysis of the effect of environment on the star-formation activity of galaxies within the Early Data Release (EDR) of the Sloan Digital Sky Survey (SDSS). We have used the Hα emission line to derive the star-formation rate (SFR) for each galaxy within a volume-limited sample of 8598 galaxies with 0.05 ≤ z ≤ 0.095 and M(r * ) ≤ −20.45. We find that the SFR of galaxies is strongly correlated with the local (projected) galaxy density and thus we present here the density-SFR relation that is analogous to the density-morphology relation. The effect of density on the SFR of galaxies is seen in three ways. First, the overall distribution of SFRs is shifted to lower values in dense environments compared with the field population. Second, the effect is most noticeable for the strongly star-forming galaxies (Hα EW > 5Å) in the 75 th percentile of the SFR distribution. Third, there is a "break" (or characteristic density) in the density-SFR relation at a local galaxy density of ∼ 1 h −2 75 Mpc −2 . To understand this break further, we have studied the SFR of galaxies as a function of clustercentric radius from 17 clusters and groups objectively selected from the SDSS EDR data. The distribution of SFRs of cluster galaxies begins to change, compared with the field population, at a clustercentric radius of 3-4 virial radii (at the > 1σ statistical significance), which is consistent with the characteristic break in density that we observe in the density-SFR relation. This effect with clustercentric radius is again most noticeable for the most strongly star-forming galaxies.Our tests suggest that the density-morphology relation alone is unlikely to explain the density-SFR relation we observe. For example, we have used the (inverse) concentration index of SDSS galaxies to classify late-type galaxies and show that the distribution of the star-forming (EW Hα > 5Å) late-type galaxies is different in dense regions (within 2 virial radii) compared with similar galaxies in the field. However, at present, we are unable to make definitive statements about the independence of the density-morphology and density-SFR relation.We have tested our work against potential systematic uncertainties including stellar absorption, reddening, SDSS survey strategy, SDSS analysis pipelines and aperture bias. Our observations are in qualitative agreement with recent simulations of hierarchical galaxy formation that predict a decrease in the SFR of galaxies within the virial radius. Our results are in agreement with recent 2dF Galaxy Redshift Survey results as well as consistent with previous observations of a decrease in the SFR of galaxies in the cores of distant clusters. Taken all together, these works demonstrate that the decrease in SFR of galaxies in dense environments is a universal phenomenon over a wide range in density (from 0.08 to 10 h −2 75 Mpc −2 ) and redshift (out to z ≃ 0.5).

We analyze scaling relations and evolution histories of galaxy sizes in TNG100, part of the IllustrisTNG simulation suite. Observational qualitative trends of size with stellar mass, star-formation rate and redshift are reproduced, and a quantitative comparison of projected r-band sizes at 0 z 2 shows agreement to much better than 0.25 dex. We follow populations of z = 0 galaxies with a range of masses backwards in time along their main progenitor branches, distinguishing between main-sequence and quenched galaxies. Our main findings are as follows. (i) At M * ,z=0 10 9.5 M , the evolution of the median main progenitor differs, with quenched galaxies hardly growing in median size before quenching, whereas main-sequence galaxies grow their median size continuously, thus opening a gap from the progenitors of quenched galaxies. This is partly because the main-sequence high-redshift progenitors of quenched z = 0 galaxies are drawn from the lower end of the size distribution of the overall population of main-sequence high-redshift galaxies. (ii) Quenched galaxies with M * ,z=0 10 9.5 M experience a steep size growth on the size-mass plane after their quenching time, but with the exception of galaxies with M * ,z=0 10 11 M , the size growth after quenching is small in absolute terms, such that most of the size (and mass) growth of quenched galaxies (and its variation among them) occurs while they are still on the main-sequence. After they become quenched, the size growth rate of quenched galaxies as a function of time, as opposed to versus mass, is similar to that of main-sequence galaxies. Hence, the size gap is retained down to z = 0.

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 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; hese 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 * /L i . Further, we use the observed relation between restframe (g − i) and M * /L i 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 * /L i to an accuracy of 0.

We present the quantitative rest-frame B morphological evolution and galaxy merger fraction at 0:2 < z < 1:2 as observed by the All-Wavelength Extended Groth Strip International Survey (AEGIS). We use the Gini coefficient and M 20 to identify major mergers and classify galaxy morphology for a volume-limited sample of 3009 galaxies brighter than 0:4L Ã B , assuming pure luminosity evolution. We find that the merger fraction remains roughly constant at 10% AE 2% for 0:2 < z < 1:2. The fraction of E/S0/Sa galaxies increases from 21% AE 3% at z $ 1:1 to 44% AE 9% at z $ 0:3, while the fraction of SbYIr galaxies decreases from 64% AE 6% at z $ 1:1 to 47% AE 9% at z $ 0:3. The majority of z < 1:2 Spitzer MIPS 24 m sources with L( IR) > 10 11 L are disk galaxies, and only $15% are classified as major merger candidates. Edge-on and dusty disk galaxies (SbYIr) are almost a third of the red sequence at z $ 1:1, while E/S0/Sa make up over 90% of the red sequence at z $ 0:3. Approximately 2% of our full sample are red mergers. We conclude (1) the merger rate does not evolve strongly between 0:2 < z < 1:2; (2) the decrease in the volumeaveraged star formation rate density since z $ 1 is a result of declining star formation in disk galaxies rather than a disappearing population of major mergers; (3) the build-up of the red sequence at z < 1 can be explained by a doubling in the number of spheroidal galaxies since z $ 1:2.

The Sloan Digital Sky Survey (SDSS) first data release provides a database of ≈ 106000 unique galaxies in the main galaxy sample with measured spectra. A sample of star-forming (SF) galaxies are identified from among the 3079 of these having 1.4 GHz luminosities from FIRST, by using optical spectral diagnostics. Using 1.4 GHz luminosities as a reference star formation rate (SFR) estimator insensitive to obscuration effects, the SFRs derived from the measured SDSS Hα, [Oii] and u-band luminosities, as well as far-infrared luminosities from IRAS, are compared. It is established that straightforward corrections for obscuration and aperture effects reliably bring the SDSS emission line and photometric SFR estimates into agreement with those at 1.4 GHz, although considerable scatter (≈ 60%) remains in the relations. It thus appears feasible to perform detailed investigations of star formation for large and varied samples of SF galaxies through the available spectroscopic and photometric measurements from the SDSS. We provide herein exact prescriptions for determining the SFR for SDSS galaxies. The expected strong correlation between [Oii] and Hα line fluxes for SF galaxies is seen, but with a median line flux ratio F [OII] /F Hα = 0.23, about a factor of two smaller than that found in the sample of Kennicutt (1992). This correlation, used in deriving the [Oii] SFRs, is consistent with the luminosity-dependent relation found by Jansen et al. (2001). The median obscuration for the SDSS SF systems is found to be A Hα = 1.2 mag, while for the radio detected sample the median obscuration is notably higher, 1.6 mag, and with a broader distribution.

Citation for published item:viskeD tF nd fldryD sFuF nd hriverD FF nd u'sD FtF nd elpslnD wF nd endreD iF nd froughD F nd gluverD wFiF nd qrootesD wFF nd qunwrdhnD wFvFF nd uelvinD vFF nd vovedyD tF nd oothmD eFFqF nd ylorD iFxF nd fmfordD FF nd flndErwthornD tF nd frownD wFtFsF nd hrinkwterD wFtF nd ropkinsD eFwF nd weyerD wFtF nd xorergD F nd eokD tFeF nd egiusD xFuF nd endrewsD FuF nd fuerD eFiF nd ghingD tFrFF nd gollessD wF nd gonselieD gFtF nd groomD FwF nd hviesD vFtFwF nd he roprisD F nd hunneD vF nd irdleyD iFwF nd illisD F nd posterD gF nd prenkD gFF nd r¤ ußlerD fF nd rolwerdD fFF nd rowlettD gF nd srrD rF nd trvisD wFtF nd tonesD hFrF nd u)eD FF nd veyD gFqF nd vngeD F nd vrEv¡ opezD wFeF nd v¡ opezE¡ nhezD ¡ eFF nd wddoxD F nd wdoreD fFpF nd wxughtEoertsD F nd wo'ettD eFtF nd xiholD FgF nd ywersD wFF nd lmrD hF nd ennyD FtF nd hillippsD F nd imletD uFeF nd opesuD gFgF nd resottD wF nd rotorD F nd dlerD iFwF nd nsomD eFiF nd eiertD wF nd hrpD F nd utherlndD F nd ¡ zquezEwtD tFeF nd vn umpenD iF nd ilkinsD FwF nd illimsD F nd rightD eFrF @PHISA 9qlxy end wss essemly @qeweA X end of survey report nd dt relese PF9D wonthly noties of the oyl estronomil oietyFD RSP @PAF ppF PHVUEPIPTF Further information on publisher's website: Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. ABSTRACTThe Galaxy And Mass Assembly (GAMA) survey is one of the largest contemporary spectroscopic surveys of low redshift galaxies. Covering an area of ∼286 deg 2 (split among five survey regions) down to a limiting magnitude of r < 19.8 mag, we have collected spectra and reliable redshifts for 238 000 objects using the AAOmega spectrograph on the Anglo-Australian Telescope. In addition, we have assembled imaging data from a number of independent surveys in order to generate photometry spanning the wavelength range 1 nm-1 m. Here, we report on the recently completed spectroscopic survey and present a series of diagnostics to assess its final state and the quality of the redshift data. We also describe a number of survey aspects and procedures, or updates thereof, including changes to the input catalogue, redshifting and re-redshifting, and the derivation of ultraviolet, optical and near-infrared photometry. Finally, we present the second public release of GAMA data. In this release, we provide input catalogue and targeting information, spectra, redshifts, ultraviolet, optical and near-infrared photometry, single-component Sérsic fits, stellar masses, Hα-derived star formation rates, environment information, and group p...