We analyze the Illustris-1 hydrodynamical cosmological simulation to explore the stellar velocity dispersion of quiescent galaxies as an observational probe of dark matter halo velocity dispersion and mass. Stellar velocity dispersion is proportional to dark matter halo velocity dispersion for both central and satellite galaxies. The dark matter halos of central galaxies are in virial equilibrium and thus the stellar velocity dispersion is also proportional to dark matter halo mass. This proportionality holds even when a line-of-sight aperture dispersion is calculated in analogy to observations. In contrast, at a given stellar velocity dispersion, the dark matter halo mass of satellite galaxies is smaller than virial equilibrium expectations. This deviation from virial equilibrium probably results from tidal stripping of the outer dark matter halo. Stellar velocity dispersion appears insensitive to tidal effects and thus reflects the correlation between stellar velocity dispersion and dark matter halo mass prior to infall. There is a tight relation (<0.2 dex scatter) between line-of-sight aperture stellar velocity dispersion and dark matter halo mass suggesting that the dark matter halo mass may be estimated from the measured stellar velocity dispersion for both central and satellite galaxies. We evaluate the impact of treating all objects as central galaxies if the relation we derive is applied to a statistical ensemble. A large fraction (>2/3) of massive quiescent galaxies are central galaxies and systematic uncertainty in the inferred dark matter halo mass is <0.1 dex thus simplifying application of the simulation results to currently available observations.
We investigate the growth of massive quiescent galaxies at $z<0.6$ based on the Sloan Digital Sky Survey and the Smithsonian Hectospec Lensing Survey---two magnitude limited spectroscopic surveys of high data quality and completeness. Our three parameter model links quiescent galaxies across cosmic time by self-consistently evolving stellar mass, stellar population age sensitive $D_n4000$ index, half-light radius and stellar velocity dispersion. Stellar velocity dispersion is a robust proxy of dark matter halo mass; we use it to connect galaxies and dark matter halos and thus empirically const…
The cosmic noon (z~1.5-3) marked a period of vigorous star formation for most galaxies. However, about a third of the more massive galaxies at those times were quiescent in the sense that their observed stellar populations are inconsistent with rapid star formation. The reduced star formation activity is often attributed to gaseous outflows driven by feedback from supermassive black holes, but the impact of black hole feedback on galaxies in the young Universe is not yet definitively established. We analyze the origin of quiescent galaxies with the help of ultra-high resolution, cosmological s…
We use the stellar-mass-selected catalog from the Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH) in the COSMOS field to study the environments of galaxies via galaxy density and clustering analyses up to $z \sim 2.5$. The clustering strength of quiescent galaxies exceeds that of star-forming galaxies, implying that quiescent galaxies are preferentially located in more massive halos. When using local density measurement, we find a clear positive quiescent fraction--density relation at $z < 1$, consistent with earlier results. However, the quiescent fraction--density relation reverses…
COSMOS-Web: does halo mass alone shape the clustering of star-forming and quiescent galaxies?
Chalmers University of Technology（查尔姆斯理工大学）；Sorbonne Université（索邦大学）；CNRS（法国国家科学研究中心）；Aix Marseille University（艾克斯-马赛大学）；The University of Texas at Austin（德克萨斯大学奥斯汀分校）；University of Washington（华盛顿大学）；University of California, Santa Barbara（加州大学圣塔芭芭拉分校）；Cosmic Dawn Center (DAWN)（宇宙黎明中心）；Université Paris-Saclay（巴黎萨克雷大学）；Université Paris Cité（巴黎西岱大学）；CEA（法国原子能和替代能源委员会）；AIM（天体物理学与分子天文学研究所）；Aalto University（阿尔托大学）；Space Telescope Science Institute（太空望远镜科学研究所）
Ultra-diffuse galaxies (UDGs) are the lowest-surface brightness galaxies known, with typical stellar masses of dwarf galaxies but sizes similar to larger galaxies like the Milky Way. The reason for their extended sizes is debated, with suggested internal processes like angular momentum, feedback or mergers versus external mechanisms or a combination of both. Observationally, we know that UDGs are red and quiescent in groups and clusters while their counterparts in the field are blue and star-forming. This dichotomy suggests environmental effects as main culprit. However, this scenario is chall…
Red quasars may represent a young stage of galaxy evolution that provide important feedback to their host galaxies. We are studying a population of extremely red quasars (ERQs) with exceptionally fast and powerful outflows, at median redshift $z$ = 2.6. We present Keck/KCWI integral field spectra of 11 ERQs, which have a median color $i-W3$ = 5.9~mag, median $\left\langle L_{\text{bol}} \right\rangle$ $\approx$ 5 $\times$ $10^{47}$ erg s$^{-1}$, Ly$α$ halo luminosity $\left\langle L_{\text{halo}} \right\rangle$ $=$ 5 $\times$ $10^{43}$ erg s$^{-1}$, and maximum linear size $>128$ kpc. The ERQ …
We examine the relation between stellar mass and central stellar velocity dispersion-the M-sigma relation-for massive quiescent galaxies at z<0.7. We measure the local relation from the Sloan Digital Sky Survey and the intermediate redshift relation from the Smithsonian Hectospec Lensing Survey. Both samples are highly complete (>85%) and we consistently measure the stellar mass and velocity dispersion for the two samples. The M-sigma relation and its scatter are independent of redshift with sigma ~ M^0.3 for M>10^10.3 M_solar. The measured slope of the M-sigma relation is the same as the scal…
It has been recently shown that the halo near the Sun contains several kinematic substructures associated to past accretion events. For the more distant halo, there is evidence of large-scale density variations -- in the form of stellar clouds or overdensities. We study the link between the local halo kinematic groups and three of these stellar clouds: the Hercules-Aquila cloud, the Virgo Overdensity, and the Eridanus-Phoenix overdensity. We perform orbital integrations in a standard Milky Way potential of a local halo sample extracted from Gaia eDR3, with the goal of predicting the location o…
We analyse the star formation rates (SFRs), colours, and dust extinctions of galaxies in massive (10^12.5-10^13.5 Msun) haloes at z~2 in high-resolution, cosmological zoom-in simulations as part of the Feedback in Realistic Environments (FIRE) project. The simulations do not model feedback from active galactic nuclei (AGN) but reproduce well the observed relations between stellar and halo mass and between stellar mass and SFR. About half (a third) of the simulated massive galaxies (massive central galaxies) at z~2 have broad-band colours classifying them as 'quiescent', and the fraction of qui…
We use MMT spectroscopy and deep Subaru Hyper Suprime-Cam (HSC) imaging to compare the spectroscopic central stellar velocity dispersion of quiescent galaxies with the effective dispersion of the dark matter halo derived from the stacked lensing signal. The spectroscopic survey (the Smithsonian Hectospec Lensing Survey) provides a sample of 4585 quiescent galaxy lenses with measured line-of-sight central stellar velocity dispersion ($σ_{\rm SHELS}$) that is more than 85% complete for $R < 20.6$, $D_{n}4000> 1.5$ and $M_{\star} > 10^{9.5}{\rm M}_{\odot}$. The median redshift of the sample of le…
Cosmic Vine: High abundance of massive galaxies and dark matter halos in a forming cluster at z=3.44
Cosmic Dawn Center (DAWN)（宇宙黎明中心）；DTU Space, Technical University of Denmark（丹麦技术大学空间研究所）；CEA, IRFU, DAp, AIM, Université Paris-Saclay, Université Paris Cité, Sorbonne Paris Cité, CNRS（法国原子能和替代能源委员会、法国研究与发展创新局、达普实验室、天体物理与成像实验室、巴黎萨克雷大学、巴黎西岱大学、索邦巴黎西岱大学、法国国家科学研究中心）；Instituto de Física, Pontificia Universidad Católica de Valparaíso（天主教瓦莱帕尔索大学物理研究所）；Instituto de Física y Astronomía, Universidad de Valparaíso（瓦尔帕莱索大学物理与天文研究所）；Millennium Nucleus for Galaxies (MINGAL)（星系千年核）；School of Astronomy and Space Science, Nanjing University（南京大学天文与空间科学学院）
We present new optical imaging and spectroscopy and HI spectral line imaging of the dwarf galaxy ADBS 113845+2008 (hereafter ADBS 1138). This metal-poor (Z~30% Z_Sun), "post-starburst" system has one of the most compact stellar distributions known in any galaxy to date (B-band exponential scale length =0.57 kpc). In stark contrast to the compact stellar component, the neutral gas is extremely extended; HI is detected to a radial distance of ~25 kpc at the 10^19 cm^-2 level (>44 B-band scale lengths). Comparing to measurements of similar "giant disk" dwarf galaxies in the literature, ADBS 1138 …
We present ALMA CO(2-1) spectroscopy of 6 massive (log$_{10}$M$_{\rm{*}}/\rm{M}_\odot>$11.3) quiescent galaxies at $z\sim1.5$. These data represent the largest sample using CO emission to trace molecular gas in quiescent galaxies above $z>1$, achieving an average 3$σ$ sensitivity of M$_{\rm{H_{2}}}\sim10^{10}\rm{M}_\odot$. We detect one galaxy at 4$σ$ significance and place upper limits on the molecular gas reservoirs of the other 5, finding molecular gas mass fractions M$_{\rm{H_{2}}}$/M$_{\rm{*}}$=f$_{\rm{H_{2}}}<2-6$% (3$σ$ upper limits). This is 1-2 orders of magnitude lower than coeval st…
Protoclusters of galaxies have been found in the last quarter century. However, most of them have been found through the overdensity of star-forming galaxies, and there had been no known structures identified by multiple spectroscopically confirmed quiescent galaxies at $z>2.5$. In this letter, we report the discovery of an overdense structure of massive quiescent galaxies with the spectroscopic redshift $z=2.77$ in the COSMOS field, QO-1000. We first photometrically identify this structure as a $4.2σ$ overdensity with 14 quiescent galaxies in $7\times4\ {\rm pMpc^2}$ from the COSMOS2020 catal…
CHANG-ES. XXXVIII. A Thin Radio Halo Shaped by Slow Cosmic-Ray Transport in the Quiescent Galaxy NGC 4565
University of Science and Technology of China（中国科学技术大学）；Purple Mountain Observatory, Chinese Academy of Sciences（中国科学院紫金山天文台）；Hamburger Sternwarte, Universität Hamburg（汉堡天文台，汉堡大学）；Max-Planck-Institut für Radioastronomie（马克斯·普朗克射电天文研究所）；Queen’s University（女王大学）；Department of Astronomy, University of Massachusetts, Amherst（马萨诸塞大学阿默斯特分校天文学系）；Ruhr University Bochum（鲁尔大学波鸿分校）
Cosmic rays play a pivotal role in launching galactic winds, particularly in quiescently star-forming galaxies where the hot gas alone is not sufficient to drive a wind. Except for the Milky Way, not much is known about the transport of cosmic rays in galaxies. In this Letter, we present low-frequency observations of the nearby edge-on spiral galaxy NGC 4565 using the LOw-Frequency ARray (LOFAR). With our deep 144-MHz observations, we obtain a clean estimate of the emission originating from old cosmic-ray electrons (CRe), which is almost free from contamination by thermal emission. We measured…
The First Systematic Survey of Stellar Halos in High-Inclination Galaxies Reveals Unusually Quiescent Merger Histories of Nearby Galaxies
University of Science and Technology of China（中国科学技术大学）；Shanghai Jiao Tong University（上海交通大学）；University of Oxford（牛津大学）；Instituto de Astrofísica de Canarias（加那利天体物理研究所）；Universidad de La Laguna（拉各拉纳大学）
On the unique evolutionary mechanisms of massive quiescent galaxies in the epoch of reionisation
Swinburne University of Technology（斯威本科技大学）；JWST Australia Data Centre [JADC], Swinburne Advanced Manufacturing and Design Centre [AMDC]（JWST澳大利亚数据中心，斯威本先进制造与设计中心）
We use photometric redshifts and statistical background subtraction to measure stellar mass functions in galaxy group-mass ($4.5-8\times10^{13}~\mathrm{M}_\odot$) haloes at $1<z<1.5$. Groups are selected from COSMOS and SXDF, based on X-ray imaging and sparse spectroscopy. Stellar mass ($M_{\mathrm{stellar}}$) functions are computed for quiescent and star-forming galaxies separately, based on their rest-frame $UVJ$ colours. From these we compute the quiescent fraction and quiescent fraction excess (QFE) relative to the field as a function of $M_{\mathrm{stellar}}$. QFE increases with $M_{\math…
The total luminosity of satellite galaxies around a central galaxy, L$_{sat}$, is a powerful metric for probing dark matter halos. In this paper we use data from the Sloan Digital Sky Survey and DESI Legacy Imaging Surveys to explore the relationship between L$_{sat}$ and various observable galaxy properties for a sample of 117,966 central galaxies out to $z = 0.15$. At fixed stellar mass, every galaxy property we explore shows a correlation with L$_{sat}$. This implies that dark matter halos play a possibly significant role in determining these secondary galaxy properties. We quantify these c…
The massive galaxy population above the characteristic Schechter mass M*~10^10.6 Msun contributes to about half of the total stellar mass in the local Universe. These massive galaxies usually reside in hot dark matter haloes above the critical shock-heating mass ~10^12 Msun, where the external cold gas supply to these galaxies is expected to be suppressed. When galaxies run out of their cold gas reservoir, they become dead and quiescent. Therefore, massive quiescent galaxies living in hot haloes are commonly believed to be gas-poor. Based on the data from SDSS, ALFALFA, GASS and COLD GASS surv…
The Role of Environment in Shaping the Assembly Timelines of Massive Quiescent Galaxies at Cosmic Noon
ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D)（ARC三维全天空天体物理学卓越中心）；INAF, Astrophysics and Space Science Observatory Bologna（意大利国家天体物理研究所博洛尼亚天文台）；Cavendish Laboratory - Astrophysics Group, University of Cambridge（剑桥大学卡文迪许实验室）；Institute for Computational & Data Sciences, The Pennsylvania State University（宾夕法尼亚州立大学计算与数据科学研究所）；Institute for Gravitation and the Cosmos, The Pennsylvania State University（宾夕法尼亚州立大学引力与宇宙研究所）；Departamento de Astronomía, Universidad de Chile（智利大学天文学系）；Research School of Astronomy and Astrophysics, Australian National University（澳大利亚国立大学天文与天体物理研究学院）；Dipartimento di Fisica e Astronomia, Università di Bologna（博洛尼亚大学物理与天文学系）
We study the mass spectrum of destroyed dwarfs that contribute to the accreted stellar mass of Milky Way (MW) mass M_vir ~ 10^12.1 M_sun) halos using a suite of 45 zoom-in, dissipationless simulations. Empirical models are employed to relate (peak) subhalo mass to dwarf stellar mass, and we use constraints from z=0 observations and hydrodynamical simulations to estimate the metallicity distribution of the accreted stellar material. The dominant contributors to the accreted stellar mass are relatively massive dwarfs with M_star ~ 10^8-10^10 M_sun. Halos with more quiescent accretion histories t…
We study the connection between active galactic nuclei (AGN) and their host galaxies through cosmic time in the large-scale cosmological IllustrisTNG simulations. We first compare BH properties, i.e. the hard X-ray BH luminosity function, AGN galaxy occupation fraction, and distribution of Eddington ratios, to available observational constraints. The simulations produce a population of BHs in good agreement with observations, but we note an excess of faint AGN in hard X-ray (L_x ~ 10^{43-44} erg/s), and a lower number of bright AGN (L_x>10^{44} erg/s), a conclusion that varies quantitatively b…
The influence of both major and minor mergers is expected to significantly affect gradients of stellar ages and metallicities in the outskirts of galaxies. Measurements of observed gradients are beginning to reach large radii in galaxies, but a theoretical framework for connecting the findings to a picture of galactic build-up is still in its infancy. We analyze stellar populations of a statistically representative sample of quiescent galaxies over a wide mass range from the Illustris simulation. We measure metallicity and age profiles in the stellar halos of quiescent Illustris galaxies rangi…
The mean size ( effective radius $R_e$) of Massive Galaxies (MGs, $M_{\rm star}>10^{11.2}M_\odot$) is observed to increase steadily with cosmic time. It is still unclear whether this trend originates from the size growth of individual galaxies (via, e.g., mergers and/or AGN feedback) or from the inclusion of larger galaxies entering the selection at later epochs (progenitor bias). We here build a data-driven, flexible theoretical framework to probe the structural evolution of MGs. We assign galaxies to dark matter haloes via stellar mass-halo mass (SMHM) relations with varying high-mass slopes…
Previous work has demonstrated that at a given stellar mass, quiescent galaxies are more strongly clustered than star-forming galaxies. The contribution to this signal from central, as opposed to satellite, galaxies is not known, which has strong implications for galaxy evolution models. To investigate the contribution from central galaxies, here we present measurements of the clustering of isolated primary (IP) galaxies, used as a proxy for central galaxies, at ${0.2<z<0.9}$ with data from the PRIMUS galaxy redshift survey. Using a sample of spectroscopic redshifts for $\sim60,000$ galaxies w…
This chapter presents a review of the current state of knowledge on the cool (T ~ 1e4 K) halo gas content around massive galaxies at z ~ 0.2-2. Over the last decade, significant progress has been made in characterizing the cool circumgalactic gas in massive halos of Mh ~ 1e12-1e14 Msun at intermediate redshifts using absorption spectroscopy. Systematic studies of halo gas around massive galaxies beyond the nearby universe are made possible by large spectroscopic samples of galaxies and quasars in public archives. In addition to accurate and precise constraints for the incidence of cool gas in …
We use weak gravitational lensing to measure mean mass profiles around Locally Brightest Galaxies (LBGs). These are selected from the SDSS/DR7 spectroscopic and photometric catalogues to be brighter than any neighbour projected within 1.0 Mpc and differing in redshift by $<1000$ km/s. Most ($> 83\%$) are expected to be the central galaxies of their dark matter halos. Previous stacking analyses have used this LBG sample to measure mean Sunyaev-Zeldovich flux and mean X-ray luminosity as a function of LBG stellar mass. In both cases, a simulation of the formation of the galaxy population was use…
We present an analysis of the clustering of high-redshift galaxies in the recently completed 94 deg$^2$ Spitzer-SPT Deep Field survey. Applying flux and color cuts to the mid-infrared photometry efficiently selects galaxies at $z\sim1.5$ in the stellar mass range $10^{10}-10^{11}M_\odot$, making this sample the largest used so far to study such a distant population. We measure the angular correlation function in different flux-limited samples at scales $>6^{\prime \prime}$ (corresponding to physical distances $>0.05$ Mpc) and thereby map the one- and two-halo contributions to the clustering. W…
We use the semi-analytic model developed by Henriques et al. (2015) to explore the origin of star formation history diversity for galaxies that lie at the centre of their dark matter haloes and have present-day stellar masses in the range 5-8 $\times$ 10$^{10}$ M$_{\odot}$, similar to that of the Milky Way. In this model, quenching is the dominant physical mechanism for introducing scatter in the growth histories of these galaxies. We find that present-day quiescent galaxies have a larger variety of growth histories than star-formers since they underwent 'staggered quenching' - a term describi…
We study the statistical distribution of satellites around star-forming and quiescent central galaxies at 1<z<3 using imaging from the FourStar Galaxy Evolution Survey (ZFOURGE) and the Cosmic Assembly Near-IR Deep Extragalactic Legacy Survey (CANDELS). The deep near-IR data select satellites down to $\log(M/M_\odot)>9$ at z<3. The radial satellite distribution around centrals is consistent with a projected NFW profile. Massive quiescent centrals, $\log(M/M_\odot)>10.78$, have $\sim$2 times the number of satellites compared to star-forming centrals with a significance of 2.7$σ$ even after acco…
Current cosmological models indicate that the Milky Way's stellar halo was assembled from many smaller systems. Based on the apparent absence of the most metal-poor stars in present-day dwarf galaxies, recent studies claimed that the true Galactic building blocks must have been vastly different from the surviving dwarfs. The discovery of an extremely iron-poor star (S1020549) in the Sculptor dwarf galaxy based on a medium-resolution spectrum cast some doubt on this conclusion. However, verification of the iron-deficiency and measurements of additional elements, such as the alpha-element Mg, ar…
This paper presents a study of the chemical compositions in cool gas around a sample of 27 intermediate-redshift galaxies. The sample comprises 13 massive quiescent galaxies at z=0.40-0.73 probed by QSO sightlines at projected distances d=3-400 kpc, and 14 star-forming galaxies at z=0.10-1.24 probed by QSO sightlines at d=8-163 kpc. The main goal of this study is to examine the radial profiles of the gas-phase Fe/α ratio in galaxy halos based on the observed Fe II to Mg II column density ratios. Because Mg+ and Fe+ share similar ionization potentials, the relative ionization correction is smal…
We study the dependence of angular two-point correlation functions on stellar mass ($M_{*}$) and specific star formation rate (sSFR) of $M_{*}>10^{10}M_{\odot}$ galaxies at $z\sim1$. The data from UKIDSS DXS and CFHTLS covering 8.2 deg$^{2}$ sample scales larger than 100 $h^{-1}$Mpc at $z\sim1$, allowing us to investigate the correlation between clustering, $M_{*}$, and star formation through halo modeling. Based on halo occupation distributions (HODs) of $M_{*}$ threshold samples, we derive HODs for $M_{*}$ binned galaxies, and then calculate the $M_{*}/M_{\rm halo}$ ratio. The ratio for cent…
We use a 27.6 deg$^2$ survey to measure the clustering of $gzK_s$-selected quiescent galaxies at $z\sim1.6$, focusing on ultra-massive quiescent galaxies. We find that $z\sim1.6$ Ultra-Massive Passively Evolving Galaxies (UMPEGs), which have $K_s(AB)<19.75$ (stellar masses of $M_{stars}$ $>\sim 10^{11.4}M_{\odot}$ and mean $<$$M_{stars}$$>$ = $10^{11.5}M_{\odot}$), cluster more strongly than any other known galaxy population at high redshift. Comparing their correlation length, $r_0 = 29.77 \pm 2.75$ $ h^{-1}$Mpc, with the clustering of dark matter halos in the Millennium XXL N-body simulation…
We investigate the distribution of central velocity dispersions for quiescent galaxies in the SDSS at $0.03 \leq z \leq 0.10$. To construct the field velocity dispersion function (VDF), we construct a velocity dispersion complete sample of quiescent galaxies with Dn4000$ > 1.5$. The sample consists of galaxies with central velocity dispersion larger than the velocity dispersion completeness limit of the SDSS survey. Our VDF measurement is consistent with previous field VDFs for $σ> 200$ km s$^{-1}$. In contrast with previous results, the VDF does not decline significantly for $σ< 200$ km s$^{-…
We describe an extension of the halo-based galaxy group-finding algorithm. We add freedom to the algorithm in order to more accurately determine which galaxies are central and which are satellites, and to provide unbiased estimates of halo masses. We focus on determination of the galaxy-halo relations for star-forming and quiescent galaxies. The added freedom in the group-finding algorithm is self-calibrated using observations of color-dependent galaxy clustering, as well as measurements of the total satellite luminosity in deep imaging data around stacked samples of spectroscopic central gala…
We perform a series of controlled N-body simulations of growing disc galaxies within non-growing, live dark matter haloes of varying mass and concentration. Our initial conditions include either a low-mass disc or a compact bulge. New stellar particles are continuously added on near-circular orbits to the existing disc, so spiral structure is continuously excited. To study the effect of combined spiral and giant molecular cloud (GMC) heating on the discs we introduce massive, short-lived particles that sample a GMC mass function. An isothermal gas component is introduced for a subset of the mo…
We present a measurement of the spatial clustering of massive compact galaxies at $1.2\le z \le 3$ in CANDELS/3D-HST fields. We obtain the correlation length for compact quiescent galaxies (cQGs) at $z\sim1.6$ of $r_{0}=7.1_{-2.6}^{+2.3}\ h^{-1}Mpc$ and compact star forming galaxies (cSFGs) at $z\sim2.5$ of $r_{0}=7.7_{-2.9}^{+2.7}\ h^{-1}Mpc$ assuming a power-law slope $γ=1.8$. The characteristic dark matter halo masses $M_H$ of cQGs at $z\sim1.6$ and cSFGs at $z\sim2.5$ are $\sim7.1\times 10^{12}\ h^{-1} M_\odot$ and $\sim4.4\times10^{12}\ h^{-1} M_\odot$, respectively. Our clustering result…
We study the roles of stellar mass and environment in quenching the star formation activity of a large set of simulated galaxies by taking advantage of an analytic model coupled to the merger tree extracted from an N-body simulation. The analytic model has been set to match the evolution of the global stellar mass function since redshift $z\sim 2.3$ and give reasonable predictions of the star formation history of galaxies at the same time. We find that stellar mass and environment play different roles: the star formation rate/specific star formation rate-$M_*$ relations are independent of the …
We present an observational study of the stellar mass function of satellite galaxies around central galaxies at 0.2<z<1.2. Using statistical background subtraction of contaminating sources we derive satellite stellar mass distributions in four bins of central galaxy mass in three redshift ranges. Our results show that the stellar mass function of satellite galaxies increases with central galaxy mass, and that the distribution of satellite masses at fixed central mass is at most weakly dependent on redshift. We conclude that the average mass distribution of galaxies in groups is remarkably univ…
According to the current galaxy formation paradigm, mergers and interactions play an important role in shaping present-day galaxies. The remnants of this merger activity can be used to constrain galaxy formation models. In this work we use a sample of thirty hydrodynamical simulations of Milky Way-mass halos, from the AURIGA project, to generate surface brightness maps and search for the brightest stream in each halo as a function of varying limiting magnitude. We find that none of the models shows signatures of stellar streams at $μ_{r}^{lim} \leq 25$ mag arcsec$^{-2}$. The stream detection i…
Based on the spectroscopic and shear catalogs for SDSS galaxies in the local Universe, we compare optically-selected active galactic nuclei (AGNs) with control star-forming and quiescent galaxies on galactic, inter-halo and larger scales. We find that AGNs are preferentially found in two specific stages of galaxy evolution: star-burst and `green valley' phases, and that the stellar population of their host galaxies is quite independent of stellar mass, different from normal galaxies. Combining galaxy-galaxy lensing and galaxy clustering on large scales, we measure the mass of AGN host halos. T…
We use very high-S/N stacked spectra of $\sim$29,000 nearby quiescent early-type galaxies (ETGs) from the Sloan Digital Sky Survey (SDSS) to investigate variations in their star formation histories (SFHs) with environment at fixed position along and perpendicular to the Fundamental Plane (FP). We define three classifications of local group environment based on the `identities' of galaxies within their dark matter halos: central `Brightest Group Galaxies' (BGGs); Satellites; and Isolateds (those `most massive' in a dark matter halo with no Satellites). We find that the SFHs of quiescent ETGs ar…
We test for galactic conformity at $0.2<z<1.0$ to a projected distance of 5 Mpc using spectroscopic redshifts from the PRism MUlti-object Survey (PRIMUS). Our sample consists of $\sim60,000$ galaxies in five separate fields covering a total of $\sim5.5$ square degrees, which allows us to account for cosmic variance. We identify star-forming and quiescent "isolated primary" (i.e., central) galaxies using isolation criteria and cuts in specific star formation rate. We match the redshift and stellar mass distributions of these samples, to control for correlations between quiescent fraction and re…
Where Giants Dwell: Probing the Environments of Early Massive Quiescent Galaxies
INAF - Astronomical Observatory of Trieste（意大利国家天体物理研究所的里雅斯特天文台）；IFPU - Institute for Fundamental Physics of the Universe（宇宙基础物理研究所）；Tianjin Normal University（天津师范大学）；Institute for Physics, Laboratory for Galaxy Evolution, EPFL（洛桑联邦理工学院星系演化实验室）
Linking X-ray emission to galaxy populations in GAMA groups
Instituto de Astronomía Teórica y Experimental, CONICET - UNC（理论与实验天文学研究所，阿根廷国家科学研究委员会-科尔多瓦大学）；Facultad de Matemática, Astronomía, Física y Computación, Universidad Nacional de Córdoba（数学、天文学、物理与计算学院，科尔多瓦国立大学）；Observatorio Astronómico, Universidad Nacional de Córdoba（天文台，科尔多瓦国立大学）；INAF-Osservatorio Astronomico di Trieste（意大利国家天体物理研究所的里雅斯特天文台）；IFPU-Institute for Fundamental Physics of the Universe（基础宇宙物理学研究所）
We investigate the utility of the 3-dimensional Two-Point Correlation Function (3D 2PCF) in quantifying substructure in the stellar halo of the Milky Way, particularly as a means of constraining the accretion history of our Galaxy. We use RR Lyrae variable stars from two different surveys as tracers of the structure in the Galactic stellar halo. We compare our measurements of the 3D 2PCF in these datasets to a suite of simulations of the formation of the stellar halo from Bullock and Johnston (2005). While there is some room for interpretation, we find that the amounts of structure to be broad…
We present initial results from the "Ponos" zoom-in numerical simulations of dark matter substructures in massive ellipticals. Two very highly resolved dark matter halos with $M_{\rm vir}=1.2\times 10^{13}$ $M_{\odot}$ and $M_{\rm vir}=6.5\times 10^{12}$ $M_{\odot}$ and different ("violent" vs. "quiescent") assembly histories have been simulated down to $z=0$ in a $Λ$CDM cosmology with a total of 921,651,914 and 408,377,544 particles, respectively. Within the virial radius, the total mass fraction in self-bound $M_{\rm sub}>10^6$ $M_{\odot}$ subhalos at the present epoch is 15% for the violent…
