Galaxy And Mass Assembly (GAMA): the effect of close interactions on star formation in galaxies
L. J. M. Davies, A. S. G. Robotham, S. P. Driver, M. Alpaslan, I. K. Baldry, J. Bland-Hawthorn, S. Brough, M. J. I. Brown, M. E. Cluver, M. J. Drinkwater, C. Fo… 展开作者
L. J. M. Davies, A. S. G. Robotham, S. P. Driver, M. Alpaslan, I. K. Baldry, J. Bland-Hawthorn, S. Brough, M. J. I. Brown, M. E. Cluver, M. J. Drinkwater, C. Foster, M. W. Grootes, I. S. Konstantopoulos, M. A. Lara-Lopez, A. R. Lopez-Sanchez, J. Loveday, M. J. Meyer, A. J. Moffett, P. Norberg, M. S. Owers, C. C. Popescu, R. De Propris, R. Sharp, R. J. Tuffs, L. Wang, S. M. Wilkins, L. Dunne N. Bourne, M. W. L. Smith
The modification of star formation (SF) in galaxy interactions is a complex process, with SF observed to be both enhanced in major mergers and suppressed in minor pair interactions. Such changes likely to arise on short timescales and be directly related to the galaxy-galaxy interaction time. Here we investigate the link between dynamical phase and direct measures of SF on different timescales for pair galaxies, targeting numerous star-formation rate (SFR) indicators and comparing to pair separation, individual galaxy mass and pair mass ratio. We split our sample into the higher (primary) and lower (secondary) mass galaxies in each pair and find that SF is indeed enhanced in all primary galaxies but suppressed in secondaries of minor mergers. We find that changes in SF of primaries is consistent in both major and minor mergers, suggesting that SF in the more massive galaxy is agnostic to pair mass ratio. We also find that SF is enhanced/suppressed more strongly for short-time duration SFR indicators (e.g. H-alpha), highlighting recent changes to SF in these galaxies, which are likely to be induced by the interaction. We propose a scenario where the lower mass galaxy has its SF suppressed by gas heating or stripping, while the higher mass galaxy has its SF enhanced, potentially by tidal gas turbulence and shocks. This is consistent with the seemingly contradictory observations for both SF suppression and enhancement in close pairs.
The Galaxy And Mass Assembly Survey (GAMA) covers five fields with highly complete spectroscopic coverage ($>95$ per cent) to intermediate depths ($r<19.8$ or $i < 19.0$ mag), and collectively spans 250 square degrees of Equatorial or Southern sky. Four of the GAMA fields (G09, G12, G15 and G23) reside in the ESO VST KiDS and ESO VISTA VIKING survey footprints, which combined with our GALEX, WISE and Herschel data provide deep uniform imaging in the $FUV\,NUV\,ugriZYJHK_s\,W1\,W2\,W3\,W4\,P100\,P160\,S250\,S350\,S500$ bands. Following the release of KiDS DR4, we describe the process by which w…
Using a volume-limited sample of 550 groups from the Galaxy And Mass Assembly (GAMA) Galaxy Group Catalogue spanning the halo mass range $12.8 < \log [M_{h}/M] < 14.2$, we investigate the merging potential of central Brightest Group Galaxies (BGGs). We use spectroscopically-confirmed close-companion galaxies as an indication of the potential stellar mass build-up of low-redshift BGGs, $z \leq 0.2$. We identify 17 close-companion galaxies with projected separations $r_{p} < 30$ kpc, relative velocities $Δv \leq 300$ km s$^{-1}$, and stellar-mass ratios $M_{BGG}/M_{CC} \leq 4$ relative to the BG…
The star formation rate in galaxies is well known to correlate with stellar mass (the `star-forming main sequence'). Here we extend this further to explore any additional dependence on galaxy surface brightness, a proxy for stellar mass surface density. We use a large sample of low redshift ($z \leq 0.08$) galaxies from the GAMA survey which have both SED derived star formation rates and photometric bulge-disc decompositions, the latter providing measures of disc surface brightness and disc masses. Using two samples, one of galaxies fitted by a single component with Sérsic index below 2 and on…
Galaxy And Mass Assembly (GAMA): The Most Isolated GAMA Galaxies
University of Bristol（布里斯托大学）；Finnish Centre for Astronomy with ESO, University of Turku（芬兰埃索天文学中心，图尔库大学）；Department of Physics and Astronomy, Botswana International University of Science and Technology（博茨瓦纳国际科学与技术大学物理与天文系）；Astrophysics Research Institute, Liverpool John Moores University（利物浦约翰摩尔斯大学天体物理研究所）；Macquarie University（麦考瑞大学）
In this study we present a new experimental design using clustering-based redshift inference to measure the evolving galaxy luminosity function (GLF) spanning 5.5 decades from $L \sim 10^{11.5}$ to $ 10^6 ~ \mathrm{L}_\odot$. We use data from the Galaxy And Mass Assembly (GAMA) survey and the Kilo-Degree Survey (KiDS). We derive redshift distributions in bins of apparent magnitude to the limits of the GAMA-KiDS photometric catalogue: $m_r \lesssim 23$; more than a decade in luminosity beyond the limits of the GAMA spectroscopic redshift sample via clustering-based redshift inference. This tech…
We explore how the group environment may affect the evolution of star-forming galaxies. We select 1197 Galaxy And Mass Assembly (GAMA) groups at $0.05\leq z \leq 0.2$ and analyze the projected phase space (PPS) diagram, i.e. the galaxy velocity as a function of projected group-centric radius, as a local environmental metric in the low-mass halo regime $10^{12}\leq (M_{200}/M_{\odot})< 10^{14}$. We study the properties of star-forming group galaxies, exploring the correlation of star formation rate (SFR) with radial distance and stellar mass. We find that the fraction of star-forming group memb…
We study the radio emission of the most massive galaxies in a sample of dynamically relaxed and un-relaxed galaxy groups from Galaxy and Mass Assembly (GAMA). The dynamical state of the group is defined by the stellar dominance of the brightest group galaxy, e.g. the luminosity gap between the two most luminous members, and the offset between the position of the brightest group galaxy and the luminosity centroid of the group. We find that the radio luminosity of the most massive galaxy in the group strongly depends on its environment, such that the brightest group galaxies in dynamically young…
We present an entirely new sample of 388 low-mass galaxies ($M_\star \leq 10^{10} M_\odot$) that have spectroscopic signatures indicating the presence of massive black holes (BHs) in the form of active galactic nuclei (AGNs) or tidal disruption events (TDEs). Of these, 70 have stellar masses in the dwarf galaxy regime with $10^8 \lesssim M_\star/M_\odot \lesssim 10^{9.5}$. We identify the active galaxies by analyzing optical spectra of a parent sample of $\sim$23,000 low-mass emission-line galaxies in the Galaxy and Mass Assembly (GAMA) Survey Data Release 4, and employing four different diagn…
We use multi-wavelength data from the Galaxy and Mass Assembly (GAMA) survey to explore the cause of red optical colours in nearby (0.002<z<0.06) spiral galaxies. We show that the colours of red spiral galaxies are a direct consequence of some environment-related mechanism(s) which has removed dust and gas, leading to a lower star formation rate. We conclude that this process acts on long timescales (several Gyr) due to a lack of morphological transformation associated with the transition in optical colour. The sSFR and dust-to-stellar mass ratio of red spiral galaxies is found to be statistic…
In this paper we test if nearby blue spheroid (BSphs) galaxies may become the progenitors of star-forming spiral galaxies or passively-evolving elliptical galaxies. Our sample comprises 428 galaxies of various morphologies in the redshift range 0.002<z<0.02 (8-87 Mpc) with panchromatic data from the Galaxy and Mass Assembly survey. We find that BSph galaxies are structurally (mean effective surface brightness, effective radius) very similar to their passively-evolving red counterparts. However, their star-formation and other properties such as colour, age and metallicity are more like star-for…
Galaxy And Mass Assembly (GAMA): Deconstructing the galaxy stellar mass function by star formation and environment
Hamburger Sternwarte, Universität Hamburg（汉堡天文台，汉堡大学）；Cluster of Excellence Quantum Universe, Universität Hamburg（量子宇宙卓越集群，汉堡大学）；International Centre for Radio Astronomy Research (ICRAR), University of Western Australia（国际无线电天文学研究中心，西澳大利亚大学）；Centre for Astrophysics and Supercomputing, Swinburne University of Technology（天体物理学与超级计算中心，斯威本科技大学）
Understanding the connection between nuclear activity and galaxy environment remains critical in constraining models of galaxy evolution. By exploiting extensive catalogued data from the Galaxy and Mass Assembly (GAMA) survey, we identify a representative sample of 205 quasars at 0.1 < z < 0.35 and establish a comparison sample of galaxies, closely matched to the quasar sample in terms of both stellar mass and redshift. On scales <1 Mpc, the galaxy number counts and group membership of quasars appear entirely consistent with those of the matched galaxy sample. Despite this, we find that quasar…
Galaxy And Mass Assembly (GAMA): Trends in galaxy colours, morphology, and stellar populations with large scale structure, group, and pair environments
Galaxy populations show bimodality in a variety of properties: stellar mass, colour, specific star-formation rate, size, and Sérsic index. These parameters are our feature space. We use an existing sample of 7556 galaxies from the Galaxy and Mass Assembly (GAMA) survey, represented using five features and the K-means clustering technique, showed that the bimodalities are the manifestation of a more complex population structure, represented by between 2 and 6 clusters. Here we use Self Organizing Maps (SOM), an unsupervised learning technique which can be used to visualize similarity in a highe…
Aims. We aim to investigate if the environment (characterised by the host dark matter halo mass) plays any role in shaping the galaxy star formation main sequence (MS). Methods. The Galaxy and Mass Assembly project (GAMA) combines a spectroscopic survey with photometric information in 21 bands from the far-ultraviolet (FUV) to the far-infrared (FIR). Stellar masses and dust-corrected star-formation rates (SFR) are derived from spectral energy distribution (SED) modelling using MAGPHYS. We use the GAMA galaxy group catalogue to examine the variation of the fraction of star-forming galaxies (SFG…
Galaxy And Mass Assembly (GAMA): The Bright Void Galaxy Population in the Optical and Mid-IR
我们研究星系的性质在星系和质量大会（GAMA）调查位于半径为$>10~h^{-1}$ Mpc的空隙。利用GAMA赤道巡天，592个空星系被识别出比$M_{r} = -18.4$（我们的星等完整性极限）亮z~0.1。利用$W_{\rm{Hα}}$与[NII]/H $α$（WHAN）谱线强度诊断图，我们将它们的谱线划分为恒星形成、活动星系核或由古老的恒星星族支配。对于质量大于$5\times10^{9}$ M $_{\odot}$的天体，我们在WHAN诊断图中识别出了26个具有老恒星星族的空星系样本，这些星系被归类为被动星系和退休星系，否则它们的光谱中没有任何发射线。当与WISE中红外测光匹配时，这些被动和退休的星系显示出一系列的中红外颜色，其中一些空洞星系显示出[4.6]-[12]与完全猝灭的恒星星族不一致的颜色，随机抽取的非空洞比较样本也显示出类似的颜色分布。我们假设，这些星系的主机模糊的恒星形成，否则他们是恒星形成的中心区域以外的单纤维光谱的目标。当匹配到随机抽取的非空星系样本时，空星系和非空星系在光学和中红外颜色、形态和恒星形成活动方面表现出相似的性质，这表明它们具有可比的质量组装和淬灭历史。在中红外[4.6]-[12]色中可以看到一种趋势，这样淬灭色/被动色<1.5的空星系和非空星系的质量通常都高于$10^{10}$ M $_{\odot}$，其中内部驱动过程在星系演化中扮演…
We study the star formation rate (SFR), stellar mass ($M_{\star}$) and the gas metallicity (Z) for 4,636 galaxy pairs using the Galaxy And Mass Assembly (GAMA) survey. Our galaxy pairs lie in a redshift range of 0 $<$ $z$ $<$ 0.35, mass range of 7.5 $<$ log( M$_{\star}$/ M$_\odot$) $<$ 11.5 and $ΔV$ $<$ 1000 km s$^{-1}$. We explore variations in SFR and Z from three point of views: multiplicity, pair separation and dynamics. We define multiplicity as the number of galaxies paired with a single galaxy, and analyzed for the first time variations in SFR and Z for both, single pairs and pairs with…
We explore the constraints that can be placed on the evolutionary timescales for typical low redshift galaxies evolving from the blue cloud through the green valley and onto the red sequence. We utilise galaxies from the GAMA survey with 0.1 < z < 0.2 and classify them according to the intrinsic (u-r?) colours of their stellar populations, as determined by fits to their multi-wavelength spectral energy distributions. Using these fits to also determine stellar population ages and star formation timescales, we argue that our results are consistent with a green valley population dominated by gala…
We present a study of the relationships and environmental dependencies between stellar mass, star formation rate, and gas metallicity for more than 700 galaxies in groups up to redshift 0.35 from the Galaxy And Mass Assembly (GAMA) survey. To identify the main drivers, our sample was analyzed as a function of group-centric distance, projected galaxy number density, and stellar mass. By using control samples of more than 16000 star-forming field galaxies and volume limited samples, we find that the highest enhancement in SFR (0.3 dex) occurs in galaxies with the lowest local density. In contras…
How do galaxy properties (such as stellar mass, luminosity, star formation rate, and morphology) and their evolution depend on the mass of their host dark matter halo? Using the Galaxy and Mass Assembly (GAMA) group catalogue, we address this question by exploring the dependence on host halo mass of the luminosity function (LF) and stellar mass function (SMF) for grouped galaxies subdivided by colour, morphology and central/satellite. We find that spheroidal galaxies in particular dominate the bright and massive ends of the LF and SMF, respectively. More massive haloes host more massive and mo…
We analyse the metallicity histories of ~4,500 galaxies from the GAMA survey at z<0.06 modelled by the SED-fitting code ProSpect using an evolving metallicity implementation. These metallicity histories, in combination with the associated star formation histories, allow us to analyse the inferred gas-phase mass--metallicity relation. Furthermore, we extract the mass--metallicity relation at a sequence of epochs in cosmic history, to track the evolving mass--metallicity relation with time. Through comparison with observations of gas-phase metallicity over a large range of redshifts, we show tha…
Recently a number of studies have found a similarity between the passive fraction of central and satellite galaxies when controlled for both stellar and halo mass. These results suggest that the quenching processes that affect galaxies are largely agnostic to central/satellite status, which contradicts the traditional picture of increased satellite quenching via environmental processes such as stripping, strangulation and starvation. Here we explore this further using the Galaxy And Mass Assembly (GAMA) survey which extends to ~2dex lower in stellar mass than SDSS, is more complete for closely…
We use data from the GAMA and GALEX surveys to demonstrate that the UV upturn, an unexpected excess of ultraviolet flux from a hot stellar component, seen in the spectra of many early-type galaxies, arises from processes internal to individual galaxies with no measurable influence from the galaxies' larger environment. We first define a clean sample of passive galaxies without a significant contribution to their UV flux from low-level star formation. We confirm that galaxies with the optical colours of red sequence galaxies often have signs of residual star formation, which, without other info…
We explore the clustering of galaxy groups in the Galaxy and Mass Assembly (GAMA) survey to investigate the dependence of group bias and profile on separation scale and group mass. Due to the inherent uncertainty in estimating the group selection function, and hence the group auto-correlation function, we instead measure the projected galaxy--group cross-correlation function. We find that the group profile has a strong dependence on scale and group mass on scales $r_\bot \lesssim 1 h^{-1} \mathrm{Mpc}$. We also find evidence that the most massive groups live in extended, overdense, structures.…
Galaxy And Mass Assembly (GAMA): Accurate Panchromatic Photometry from Optical Priors using LAMBDAR
我们提出了R中的Lambda自适应多波段去混合算法（LAMBDAR），这是一种新的代码，用于计算既不匹配像素也不匹配PSF的图像之间的匹配孔径光度，使用来自高分辨率光学成像的先前孔径定义。该程序的开发是出于对大范围光度成像中一致的光度测定和不确定性的需求，用于计算光谱能量分布。我们描述的程序，具体的关键功能所需的强大的全色光度测定：传播的光圈图像具有任意分辨率，本地背景估计，光圈归一化，不确定性的确定和传播，和对象去混合。使用模拟图像，我们证明了该程序是能够恢复准确的光度测量在高分辨率，低混淆，低分辨率，高混淆，制度。我们将该程序应用于来自Galaxy And Mass Assembly（GAMA）Panchromatic Data Release（PDR; Driver et al. 2016）的21波段光度数据集，该数据集包含从远紫外到远红外的成像。我们将LAMBDAR得出的光度与Driver et al.（2016）中提出的光度进行了比较，发现数据集之间存在广泛的一致性。尽管如此，我们证明，从LAMBDAR的光度测定是优于从GAMA PDR，确定在LAMBDAR数据集中的离群值率和内在的颜色散射的减少。我们同样发现，使用LAMBDAR测光的恒星质量和恒星形成率的异常率下降。最后，我们注意到一个特殊的增加的数量的紫外线和中红外光源能够被约束，这是伴随着一个显着增加的中红外颜色颜…
In galaxy clusters, efficiently accreting active galactic nuclei (AGN) are preferentially located in the infall regions of the cluster projected phase-space, and are rarely found in the cluster core. This has been attributed to both an increase in triggering opportunities for infalling galaxies, and a reduction of those mechanisms in the hot, virialised, cluster core. Exploiting the depth and completeness ($98\,$per cent at $r<19.8\,$mag) of the Galaxy And Mass Assembly survey (GAMA), we probe down the group halo mass function to assess whether AGN are found in the same regions in groups as th…
We present a pilot study to assess the potential of Hyper Suprime-Cam Public Data Release 2 (HSC-PDR2) images for the analysis of extended faint structures within groups of galaxies. We examine the intra-group light (IGL) of the group 400138 ($M_{\rm{dyn}}= 1.3 \pm 0.5 \times 10^{13} $M$_{\odot}$, $z\sim 0.2$) from the Galaxy And Mass Assembly (GAMA) survey using Hyper-Suprime Cam Subaru Strategic Program Public Data Release 2 (HSC-PDR2) images in $g$, $r$, and $i$ bands. We present the most extended IGL measurement to date, reaching down to $μ_{g}^{\rm{lim}}=30.76$ mag arcsec$^{-2}$ ($3 σ$; $…
We describe data release 3 (DR3) of the Galaxy And Mass Assembly (GAMA) survey. The GAMA survey is a spectroscopic redshift and multi-wavelength photometric survey in three equatorial regions each of 60.0 deg^2 (G09, G12, G15), and two southern regions of 55.7 deg^2 (G02) and 50.6 deg^2 (G23). DR3 consists of: the first release of data covering the G02 region and of data on H-ATLAS sources in the equatorial regions; and updates to data on sources released in DR2. DR3 includes 154809 sources with secure redshifts across four regions. A subset of the G02 region is 95.5% redshift complete to r<19…
Combining high-fidelity group characterisation from the Galaxy and Mass Assembly (GAMA) survey and source-tailored $z<0.1$ photometry from the WISE survey, we present a comprehensive study of the properties of ungrouped galaxies, compared to 497 galaxy groups (4$\leq$ N$_{\rm FoF}$ $\leq$ 20) as a function of stellar and halo mass. Ungrouped galaxies are largely unimodal in WISE color, the result of being dominated by star-forming, late-type galaxies. Grouped galaxies, however, show a clear bimodality in WISE color, which correlates strongly with stellar mass and morphology. We find evidence f…
We explore constraints on the joint photometric and morphological evolution of typical low redshift galaxies as they move from the blue cloud through the green valley and onto the red sequence. We select GAMA survey galaxies with $10.25<{\rm log}(M_*/M_\odot)<10.75$ and $z<0.2$ classified according to their intrinsic $u^*-r^*$ colour. From single component Sérsic fits, we find that the stellar mass-sensitive $K-$band profiles of red and green galaxy populations are very similar, while $g-$band profiles indicate more disk-like morphologies for the green galaxies: apparent (optical) morphologica…
Strong gravitational lenses are a rare and instructive type of astronomical object. Identification has long relied on serendipity, but different strategies -- such as mixed spectroscopy of multiple galaxies along the line of sight, machine learning algorithms, and citizen science -- have been employed to identify these objects as new imaging surveys become available. We report on the comparison between spectroscopic, machine learning, and citizen science identification of galaxy-galaxy lens candidates from independently constructed lens catalogs in the common survey area of the equatorial fiel…
