The phenomenological study of evolving galaxy populations has shown that star forming galaxies can be quenched by two distinct processes: mass quenching and environment quenching (Peng et al. 2010). To explore the mass quenching process in local galaxies, we study the massive central disk galaxies with stellar mass above the Schechter characteristic mass. In Zhang et al. (2019), we showed that during the quenching of the massive central disk galaxies as their star formation rate (SFR) decreases, their molecular gas mass and star formation efficiency drop rapidly, but their HI gas mass remains surprisingly constant. To identify the underlying physical mechanisms, in this work we analyze the change during quenching of various structure parameters, bar frequency, and active galactic nucleus (AGN) activity. We find three closely related facts. On average, as SFR decreases in these galaxies: (1) they become progressively more compact, indicated by their significantly increasing concentration index, bulge-to-total mass ratio, and central velocity dispersion, which are mainly driven by the growth and compaction of their bulge component; (2) the frequency of barred galaxies increases dramatically, and at a given concentration index the barred galaxies have a significantly higher quiescent fraction than unbarred galaxies, implying that the galactic bar may play an important role in mass quenching; and (3) the "AGN" frequency increases dramatically from 10% on the main sequence to almost 100% for the most quiescent galaxies, which is mainly driven by the sharp increase of LINERs. These observational results lead to a self-consistent picture of how mass quenching operates.
We develop a conceptual framework and methodology to study the drivers of the quenching of galaxies, including the drivers of galactic conformity. The framework is centred on the statistic $Δ$, which is defined as the difference between the observed star-formation state of a galaxy, and a prediction of its state based on an empirical model of quenching. In particular, this work uses the average quenching effects of stellar mass and local density to construct an empirical model of quenching. $Δ$ is therefore a residual which reflects the effects of drivers of quenching not captured by stellar m…
We develop a simple yet comprehensive method to distinguish the underlying drivers of galaxy quenching, using the clustering and galaxy-galaxy lensing of red and blue galaxies in SDSS. Building on the iHOD framework developed by Zu & Mandelbaum (2015a), we consider two quenching scenarios: 1) a "halo" quenching model in which halo mass is the sole driver for turning off star formation in both centrals and satellites; and 2) a "hybrid" quenching model in which the quenched fraction of galaxies depends on their stellar mass while the satellite quenching has an extra dependence on halo mass. The …
We study the structural and environmental dependence of the star formation on the plane of stellar mass versus central core density ($Σ_{\rm 1\ kpc}$) in the nearby universe. We study the central galaxies in the sparse environment and find a characteristic population-averaged $\rm Σ_{1\ kpc} \sim 10^9-10^{9.2}\ M_{\odot}\ kpc^{-2}$, above which quenching is operating. This $\rm Σ^{crit}_{1\ kpc}$ only weakly depends on the stellar mass, suggesting that the mass-quenching of the central galaxies is more closely related to the processes that operate in the central regions than over the entire ga…
The VariableTNG project: Unveiling the physical drivers of galaxy quenching
University of Chinese Academy of Sciences（中国科学院大学）；Peking University（北京大学）；Universidad Técnica Federico Santa María（费德里科·圣玛丽亚技术大学）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）
Central galaxies make up the majority of the galaxy population, including the majority of the quiescent population at $\mathcal{M}_* > 10^{10}\mathrm{M}_\odot$. Thus, the mechanism(s) responsible for quenching central galaxies plays a crucial role in galaxy evolution as whole. We combine a high resolution cosmological $N$-body simulation with observed evolutionary trends of the "star formation main sequence," quiescent fraction, and stellar mass function at $z < 1$ to construct a model that statistically tracks the star formation histories and quenching of central galaxies. Comparing this mode…
Large-scale and local environmental drivers of quenching: tracing H$α$ concentration in X-ray and optical galaxy groups
The University of Sydney（悉尼大学）；ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D)（三维全天空天体物理学卓越研究中心）；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）；Beijing Normal University（北京师范大学）；Max Planck Institute for Extraterrestrial Physics（马克斯·普朗克地外物理研究所）
We investigate the connection between X-ray and radio-loud AGNs and the physical properties of their evolved and massive host galaxies, focussing on the mass-related quenching channel followed by $\mathcal{M}^\star (\simeq 10^{10.6} M_\odot)$ galaxies in the rest-frame NUVrK colour diagram at $0.2 < z < 0.5$. While our results confirm that (1) radio-loud AGNs are predominantly hosted by already-quenched and very massive ($M_*>10^{11}M_\odot$) galaxies, ruling out their feedback as a primary driver of $\mathcal{M}^\star$ galaxy quenching, we found that (2) X-ray AGNs affected by heavy obscurati…
We develop a 2D inclined rotating disc model, which we apply to the stellar velocity maps of 1862 galaxies taken from the MaNGA survey (SDSS public Data Release 15). We use a random forest classifier to identify the kinematic parameters that are most connected to galaxy quenching. We find that kinematic parameters that relate predominantly to the disc (such as the mean rotational velocity) and parameters that characterise whether a galaxy is rotation- or dispersion-dominated (such as the ratio of rotational velocity to velocity dispersion) are not fundamentally linked to the quenching of star …
The timescales for galaxy quenching offer clues to its underlying physical drivers. We investigate central galaxy quenching timescales in the IllustrisTNG 100-1 simulation, their evolution over time, and the pre-quenching properties of galaxies that predict their quenching timescales. Defining quenching duration $τ_q$ as the time between crossing sSFR thresholds, we find that $\sim$40% of galaxies quench rapidly with $τ_q<$1 Gyr, but a substantial tail of galaxies can take up to 10 Gyr to quench. Furthermore, 29% of galaxies that left the star forming main sequence (SFMS) more than 2 Gyr ago n…
Tracing evolutionary pathways of bar-driven quenching in local Universe disc galaxies
Indian Institute of Astrophysics（印度天文物理研究所）；Pondicherry University（本地治里大学）；Leibniz-Institut für Astrophysik Potsdam（波茨坦莱布尼茨天文物理研究所）；Ludwig-Maximilians-Universitat（路德维希-马克西米利安大学）
Ejective feedback as a quenching mechanism in the 1.5 billion years of the universe: detection of neutral gas outflow in a $z=4$ recently quenched galaxy
The suppression of star formation in the inner kiloparsec regions of barred disk galaxies due to the action of bars is known as bar quenching. We investigate here the significance of bar quenching in the global quenching of star formation in the barred galaxies and their transformation to passive galaxies in the local Universe. We do this by measuring the offset of quenched barred galaxies from star-forming main sequence galaxies in the star formation rate-stellar mass plane and comparing it with the length of the bar, which is considered as a proxy of bar quenching. We constructed the star fo…
We present near-infrared spectroscopic confirmations of a sample of 16 photometrically-selected galaxies with stellar masses log(M_star/M_sun) > 11 at redshift z > 3 from the XMM-VIDEO and COSMOS-UltraVISTA fields using Keck/MOSFIRE as part of the MAGAZ3NE survey. Eight of the ultra-massive galaxies (UMGs) have specific star formation rates (sSFR) < 0.03 Gyr-1, with negligible emission lines. Another seven UMGs show emission lines consistent with active galactic nuclei and/or star formation, while only one UMG has sSFR > 1 Gyr-1. Model star formation histories of these galaxies describe system…
We present a population study of the star formation history of 1244 Type 2 AGN host galaxies, compared to 6107 inactive galaxies. A Bayesian method is used to determine individual galaxy star formation histories, which are then collated to visualise the distribution for quenching and quenched galaxies within each population. We find evidence for some of the Type 2 AGN host galaxies having undergone a rapid drop in their star formation rate within the last 2 Gyr. AGN feedback is therefore important at least for this population of galaxies. This result is not seen for the quenching and quenched …
Star-forming galaxies can in principle be transformed into passive systems by a multitude of processes that quench star formation, such as the halting of gas accretion (starvation) or the rapid removal of gas in AGN-driven outflows. However, it remains unclear which processes are the most significant, primary drivers of the SF-passive bimodality. We address this key issue in galaxy evolution by studying the chemical properties of 80,000 local galaxies in SDSS DR7. In order to distinguish between different quenching mechanisms, we analyse the stellar metallicities of star-forming, green valley …
The star formation quenching depends on environment, but a full understanding of what mechanisms drive it is still missing. Exploiting a sample of galaxies with masses $M_\ast>10^{9.8}M_\odot$, drawn from the WIde-field Nearby Galaxy-cluster Survey (WINGS) and its recent extension OMEGAWINGS, we investigate the star formation rate (SFR) as a function of stellar mass (M$_*$) in galaxy clusters at $0.04<z<0.07$. We use non-member galaxies at 0.02$<$z$<$0.09 as field control sample. Overall, we find agreement between the SFR-M$_*$ relation in the two environments, but detect a population of clust…
The galaxy quenching process, in which a galaxy stops forming stars is a crucial stage in galaxy life. Two mechanisms for quenching are possible: halo mass quenching of central galaxies and environmental quenching of satellite galaxies. This thesis describes the satellite galaxies (SG) quenching process and its primary causes. The analysis contains a study of a large sample of 118 SGs within the Vela cosmological simulation, identified by a specific SG merger tree algorithm. We find that the quenching evolves through a typical path in the diagram of specific star formation (sSFR) vs. inner ste…
We estimate the current extinction-corrected H$α$ star formation rate (SFR) of the different morphological components that shape galaxies (bulges, bars, and disks). We use a multi-component photometric decomposition based on SDSS imaging to CALIFA Integral Field Spectroscopy datacubes for a sample of 219 galaxies. This analysis reveals an enhancement of the central SFR and specific SFR (sSFR $=$ SFR/$M_{\star}$) in barred galaxies. Along the Main Sequence, we find more massive galaxies in total have undergone efficient suppression (quenching) of their star formation, in agreement with many stu…
We present a method to flexibly and self-consistently determine individual galaxies' star formation rates (SFRs) from their host haloes' potential well depths, assembly histories, and redshifts. The method is constrained by galaxies' observed stellar mass functions, SFRs (specific and cosmic), quenched fractions, UV luminosity functions, UV-SM relations, IRX-UV relations, auto- and cross-correlation functions (including quenched and star-forming subsamples), and quenching dependence on environment; each observable is reproduced over the full redshift range available, up to 0<z<10. Key findings…
We model satellite quenching at $z \sim 1$ by combining $14$ massive ($10^{13.8} < M_{\mathrm{halo}}/\mathrm{M}_{\odot} < 10^{15}$) clusters at $0.8 < z < 1.3$ from the GOGREEN and GCLASS surveys with accretion histories of $56$ redshift-matched analogs from the IllustrisTNG simulation. Our fiducial model, which is parameterized by the satellite quenching timescale ($τ_{\rm quench}$), accounts for quenching in our simulated satellite population both at the time of infall by using the observed coeval field quenched fraction and after infall by tuning $τ_{\rm quench}$ to reproduce the observed s…
We present a study of the size--mass relation for local post-starburst (PSB) galaxies at $z\lesssim0.33$ selected from the Sloan Digital Sky Survey Data Release 8. We find that PSB galaxies with stellar mass ($M_*$) at $10^9~M_{\odot}<M_*<10^{12}~M_{\odot}$ have their galaxy size smaller than or comparable with those of quiescent galaxies (QGs). After controlling redshift and stellar mass, the sizes of PSBs are $\sim 13\%$ smaller on average than those of QGs, such differences become larger and significant towards the low-$M_*$ end, especially at $10^{9.5}~M_{\odot} \lesssim M_*\lesssim 10^{10…
It is generally assumed that galaxies are a bimodal population in both star formation and structure: star-forming galaxies are disks, while passive galaxies host large bulges or are entirely spheroidal. Here, we test this scenario by presenting a full census of the kinematic morphologies of a volume-limited sample of galaxies in the local Universe extracted from the MaNGA galaxy survey. We measure the integrated stellar line-of-sight velocity to velocity dispersion ratio ($V/σ$) for 4574 galaxies in the stellar mass range $9.75 < \log M_{\star}[\rm{M}_{\odot}] < 11.75$. We show that at fixed s…
We investigate the environmental quenching of galaxies, especially those with stellar masses (M*)$<10^{9.5} M_\odot$, beyond the local universe. Essentially all local low-mass quenched galaxies (QGs) are believed to live close to massive central galaxies, which is a demonstration of environmental quenching. We use CANDELS data to test {\it whether or not} such a dwarf QG--massive central galaxy connection exists beyond the local universe. To this purpose, we only need a statistically representative, rather than a complete, sample of low-mass galaxies, which enables our study to $z\gtrsim1.5$. …
We present a detailed analysis of the influence of the environment and of the environmental history on quenching star formation in central and satellite galaxies in the local Universe. We take advantage of publicly available galaxy catalogues obtained from applying a galaxy formation model to the Millennium simulation. In addition to halo mass, we consider the local density of galaxies within various fixed scales. Comparing our model predictions to observational data (SDSS), we demonstrate that the models are failing to reproduce the observed density dependence of the quiescent galaxy fraction…
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 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…
Despite decreasing cosmic star formation rate density over the last 10 Gyr, the stellar mass ($M_{*}$) buildups in galaxies were still progressing during this epoch. About 50\% of the current $M_{*}$ density in the universe was built over the last $\sim 8.7$ Gyr. In this research, we investigated the stellar mass buildup and quenching of spatially resolved regions within massive disk galaxies over the last 10 Gyr. We apply the spectral energy distribution (SED) fitting method to SEDs of sub-galactic regions in galaxies to derive the spatially resolved distributions of SFR and $M_{*}$ in the ga…
Misalignments between the rotation axis of stars and gas are an indication of external processes shaping galaxies throughout their evolution. Using observations of 3068 galaxies from the SAMI Galaxy Survey, we compute global kinematic position angles for 1445 objects with reliable kinematics and identify 169 (12%) galaxies which show stellar-gas misalignments. Kinematically decoupled features are more prevalent in early-type/passive galaxies compared to late-type/star-forming systems. Star formation is the main source of gas ionisation in only 22% of misaligned galaxies; 17% are Seyfert object…
We present results from MUSE spatially-resolved spectroscopy of 21 post-starburst galaxies in the centers of 8 clusters from $z\sim0.3$ to $z\sim0.4$. We measure spatially resolved star-formation histories (SFHs), the time since quenching ($t_Q$) and the fraction of stellar mass assembled in the past 1.5 Gyr ($μ_{1.5}$). The SFHs display a clear enhancement of star-formation prior to quenching for 16 out of 21 objects, with at least 10% (and up to $>50$%) of the stellar mass being assembled in the past 1.5 Gyr and $t_Q$ ranging from less than 100 Myrs to $\sim800$ Myrs. By mapping $t_Q$ and $μ…
Feedback from accreting supermassive black holes (SMBHs) is thought to be a primary driver of quenching in massive galaxies, but the best way to implement SMBH physics into galaxy formation simulations remains ambiguous. As part of the Feedback in Realistic Environments (FIRE) project, we explore the effects of different modeling choices for SMBH accretion and feedback in a suite of $\sim500$ cosmological zoom-in simulations across a wide range of halo mass (10^10-10^13 Msun). Within the suite, we vary the numerical schemes for BH accretion and feedback, the accretion efficiency, and the stren…
Environment is one of the primary drivers of galaxy evolution; via multiple mechanisms, it can control the critical process of transforming galaxies from star forming to quiescent, commonly termed "quenching". Despite its importance, however, we still do not have a clear view of how environmentally-driven quenching proceeds even in the most extreme environments: galaxy clusters and their progenitor proto-clusters. Recent advances in infrared capabilities have enabled transformative progress not only in the identification of these structures but in detailed analyses of quiescence, obscured star…
The most striking feature of the Cosmic Star Formation History (CSFH) of the Universe is a dramatic drop of the star formation (SF) activity, since z~1. In this work we investigate if the very same process of assembly and growth of structures is one of the major drivers of the observed decline. We study the contribution to the CSFH of galaxies in halos of different masses. This is done by studying the total SFR-halo mass-redshift plane from redshift 0 to redshift z~1.6 in a sample of 57 groups and clusters by using the deepest available mid- and far-infrared surveys conducted with Spitzer MIPS…
The role of small-scale environments in the quenching of massive galaxies at $1<z<5$
The Graduate University for Advanced Studies, SOKENDAI（高级研究院）；National Astronomical Observatory of Japan（日本国立天文台）；Institute for Cosmic Ray Research, The University of Tokyo（东京大学宇宙射线研究所）；Cosmic Dawn Center (DAWN)（宇宙黎明中心）；DTU Space, Technical University of Denmark（丹麦技术大学空间科学系）；Waseda University（早稻田大学）
We examine the quenched fraction of central and satellite galaxies as a function of galaxy stellar mass, halo mass, and the matter density of their large scale environment. Matter densities are inferred from our ELUCID simulation, a constrained simulation of local Universe sampled by SDSS, while halo masses and central/satellite classification are taken from the galaxy group catalog of Yang et al. The quenched fraction for the total population increases systematically with the three quantities. We find that the `environmental quenching efficiency', which quantifies the quenched fraction as fun…
Observations of low-mass satellite galaxies in the nearby Universe point towards a strong dichotomy in their star-forming properties relative to systems with similar mass in the field. Specifically, satellite galaxies are preferentially gas poor and no longer forming stars, while their field counterparts are largely gas rich and actively forming stars. Much of the recent work to understand this dichotomy has been statistical in nature, determining not just that environmental processes are most likely responsible for quenching these low-mass systems but also that they must operate very quickly …
Recent studies of galaxies in the local Universe, including those in the Local Group, find that the efficiency of environmental (or satellite) quenching increases dramatically at satellite stellar masses below ~ $10^8\ {\rm M}_{\odot}$. This suggests a physical scale where quenching transitions from a slow "starvation" mode to a rapid "stripping" mode at low masses. We investigate the plausibility of this scenario using observed HI surface density profiles for a sample of 66 nearby galaxies as inputs to analytic calculations of ram-pressure and viscous stripping. Across a broad range of host p…
Previous findings show that the existence of dense cores or bulges is the prerequisite for quenching a galaxy, leading to a proposed two-step quenching scenario: compaction and quenching. In this scenario, galaxies first grow their cores to a stellar mass surface density threshold and subsequently quenching occurs, suggesting that galaxies evolve from extended star-forming galaxies (eSFGs), through compact star-forming galaxies (cSFGs), to quenched population. In this work, we aim at examining the possible evolutionary link between eSFGs and cSFGs by identifying the trends in star formation ra…
The THESAN-ZOOM project: central starbursts and inside-out quenching govern galaxy sizes in the early Universe
University of Cambridge（剑桥大学）；The University of Texas at Dallas（德克萨斯大学达拉斯分校）；York University（约克大学）；Leibniz-Institut für Astrophysik Potsdam（波茨坦阿佩尔天体物理研究所）；University of Pennsylvania（宾夕法尼亚大学）；The University of Tokyo（东京大学）；Institute for Fundamental Physics of the Universe（基础宇宙物理研究所）；University of Edinburgh（爱丁堡大学）
We examine the spheroid growth and star formation quenching experienced by galaxies from z~3 to the present by studying the evolution with redshift of the quiescent and spheroid-dominated fractions of galaxies from the CANDELS and GAMA surveys. We compare the observed fractions with predictions from a semi-analytic model which includes prescriptions for bulge growth and AGN feedback due to mergers and disk instabilities. We facilitate direct morphological comparison by converting our model bulge-to-total stellar mass ratios to Sersic indices. We then subdivide our population into the four quad…
In the local Universe, there is a strong division in the star-forming properties of low-mass galaxies, with star formation largely ubiquitous amongst the field population while satellite systems are predominantly quenched. This dichotomy implies that environmental processes play the dominant role in suppressing star formation within this low-mass regime (${M}_{\star} \sim 10^{5.5-8}~{\rm M}_{\odot}$). As shown by observations of the Local Volume, however, there is a non-negligible population of passive systems in the field, which challenges our understanding of quenching at low masses. By appl…
Radio galaxies are among the most massive galaxies in the high redshift universe and are known to often lie in protocluster environments. We have studied the fields of seven z = 2.2 radio galaxies with HAWK-I narrow-band and broad-band imaging in order to map out their environment using Halpha emitters (HAEs). The results are compared to the blank field HAE survey HiZELS. All of the radio galaxy fields are overdense in HAEs relative to a typical HiZELS field of the same area and four of the seven are richer than all except one of 65 essentially random HiZELS subfields of the same size. The sta…
We present high spatial resolution imaging of the CO(1-0) line from the Karl G. Jansky Very Large Array (VLA) of COSMOS27289, a massive, compact star forming galaxy at z=2.234. This galaxy was selected to be structurally similar to z~2 passive galaxies. Our previous observations showed that it is very gas-poor with respect to typical star-forming galaxies at these redshifts, consistent with a rapid transition to quiescence as the molecular gas is depleted. The new data show that both the molecular gas fraction f_H2 = M_H2/M_star and the molecular gas depletion time t_dep = M_H2/SFR are lower i…
We apply the empirical galaxy--halo connection model UniverseMachine to dark matter-only zoom-in simulations of isolated Milky Way (MW)--mass halos along with their parent cosmological simulations. This application extends \textsc{UniverseMachine} predictions into the ultra-faint dwarf galaxy regime ($ 10^{2}\,\mathrm{M_{\odot}} \leqslant M_{\ast} \leqslant 10^{5}\,\mathrm{M_{\odot}}$) and yields a well-resolved stellar mass--halo mass (SMHM) relation over the peak halo mass range $10^8\,\mathrm{M_{\odot}}$ to $10^{15}\,\mathrm{M_{\odot}}$. The extensive dynamic range provided by the zoom-in s…
Understanding how galaxies cease to form stars represents an outstanding challenge for galaxy evolution theories. This process of "star formation quenching" has been related to various causes, including Active Galactic Nuclei (AGN) activity, the influence of large-scale dynamics, and the environment in which galaxies live. In this paper, we present the first results from a follow-up of CALIFA survey galaxies with observations of molecular gas obtained with the APEX telescope. Together with EDGE survey CARMA observations, we collect $^{12}$CO observations that cover approximately one effective …
