Measuring the chemical composition of galaxies is crucial to our understanding of galaxy formation and evolution models. However, such measurements are extremely challenging for quiescent galaxies at high redshifts, which have faint stellar continua and compact sizes, making it difficult to detect absorption lines and nearly impossible to spatially resolve them. Gravitational lensing offers the opportunity to study these galaxies with detailed spectroscopy that can be spatially resolved. In this work, we analyze deep spectra of MRG-M0138, a lensed quiescent galaxy at z = 1.98 which is the brightest of its kind, with an H-band magnitude of 17.1. Taking advantage of full spectral fitting, we measure $[{\rm Mg/Fe}]=0.51\pm0.05$, $[\rm{Fe/H}]=0.26\pm0.04$, and, for the first time, the stellar abundances of 6 other elements in this galaxy. We further constrained, also for the first time in a $z\sim2$ galaxy, radial gradients in stellar age, [Fe/H], and [Mg/Fe]. We detect no gradient in age or [Mg/Fe] and a slightly negative gradient in [Fe/H], which has a slope comparable to that seen in local early-type galaxies. Our measurements show that not only is MRG-M0138 very Mg-enhanced compared to the centers of local massive early-type galaxies, it is also very iron rich. These dissimilar abundances suggest that even the inner regions of massive galaxies have experienced significant mixing of stars in mergers, in contrast to a purely inside-out growth model. The abundance pattern observed in MRG-M0138 challenges simple galactic chemical evolution models that vary only the star formation timescale and shows the need for more elaborate models.
We present a study of the evolution of brightest cluster galaxies (BCGs) in a sample of clusters at $0.05 \leq z<0.35$ from the SDSS and WISE with halo masses in the range $6 \times 10^{13}M_\odot$ (massive groups) - $10^{15.5}M_\odot$ (Coma-like clusters). We analyse optical and infrared colours and stellar masses of BCGs as a function of the mass of their host haloes. We find that BCGs are mostly red and quiescent galaxies and that a minority ($\sim 9$\%) of them are star-forming. We find that the optical $g-r$ colours are consistent with those of red sequence galaxies at the same redshifts;…
REQUIEM-2D (REsolving QUIEscent Magnified galaxies with 2D grism spectroscopy) is comprised of a sample of 8 massive ($\log M_*/M_\odot > 10.6$) strongly lensed quiescent galaxies at $z\sim2$. REQUIEM-2D combines the natural magnification from strong gravitational lensing with the high spatial-resolution grism spectroscopy of \emph{Hubble Space Telescope} through a spectrophotometric fit to study spatially resolved stellar populations. We show that quiescent galaxies in the REQUIEM-2D survey have diverse formation histories manifesting as a gradient in stellar ages, including examples of (1) a…
We present stellar rotation curves and velocity dispersion profiles for 104 quiescent galaxies at $z=0.6-1$ from the Large Early Galaxy Astrophysics Census (LEGA-C) spectroscopic survey. Rotation is typically probed across 10-20kpc, or to an average of 2.7${\rm R_e}$. Combined with central stellar velocity dispersions ($σ_0$) this provides the first determination of the dynamical state of a sample selected by a lack of star formation activity at large lookback time. The most massive galaxies ($M_{\star}>2\times10^{11}\,M_{\odot}$) generally show no or little rotation measured at 5kpc ($|V_5|/σ…
One of the challenges in understanding the quenching processes for galaxies is connecting progenitor star-forming populations to their descendant quiescent populations over cosmic time. Here we attempt a novel approach to this challenge by assuming that the underlying stellar mass distribution of galaxies is not significantly altered during environmental quenching processes that solely affect the gas content of cluster galaxies, such as strangulation and ram-pressure stripping. Using the deep, high-resolution photometry of the Hubble Frontier Fields, we create resolved stellar mass maps for bo…
We select 456 galaxies with kinematically misaligned gas and stellar components from 9546 parent galaxies in MaNGA, and classify them into 72 star-forming galaxies, 142 green-valley galaxies and 242 quiescent galaxies. Comparing the spatial resolved properties of the misaligned galaxies with control samples closely match in the D$_n$4000 and stellar velocity dispersion, we find that: (1) the misaligned galaxies have lower values in $V_{\rm gas}/σ_{\rm gas}$ and $V_{\rm star}/σ_{\rm star}$ (the ratio between ordered to random motion of gas and stellar components) across the entire galaxies than…
Resolved Maps of Gas and Dust in a Massive Quiescent Galaxy at z=2 from INQUEST-JWST: Evidence of Accretion and Rejuvenation
Observatories of the Carnegie Institution for Science（卡内基科学研究所天文台）；Department of Astronomy, Tsinghua University（清华大学天文系）；Dipartimento di Fisica e Astronomia (DIFA), Università di Bologna（博洛尼塔大学物理与天文学系）；Department of Astronomy, University of Massachusetts, Amherst（马萨诸塞大学阿默斯特分校天文系）；Cosmic Dawn Center (DAWN)（宇宙黎明中心）；Centre for Astrophysics and Supercomputing, Swinburne University of Technology（斯威本科技大学天体物理与超级计算中心）
MAGAZ3NE: Spatially Resolved Ages and Chemical Abundances of Ultra-Massive Quiescent Galaxies at z $\sim$ 3.5 using JWST/NIRSpec IFU
York University（约克大学）；University of Toronto（多伦多大学）；Dunlap Institute for Astronomy & Astrophysics, University of Toronto（多伦多大学邓普勒天文学与天体物理研究所）；University of Massachusetts, Amherst（马萨诸塞大学阿默斯特分校）；University of California Davis（加州大学戴维斯分校）；University of Wisconsin-Madison（威斯康星大学麦迪逊分校）；Observatories of the Carnegie Institution for Science（卡内基科学机构天文台）；Princeton University（普林斯顿大学）
We analyse spatially-resolved deep optical spectroscopy of Brightest Cluster Galaxies (BCGs) located in 32 massive clusters with redshifts of 0.05 $\leq z \leq$ 0.30, to investigate their velocity dispersion profiles. We compare these measurements to those of other massive early-type galaxies, as well as central group galaxies, where relevant. This unique, large sample extends to the most extreme of massive galaxies, spanning M$_{K}$ between -25.7 to -27.8 mag, and host cluster halo mass M$_{500}$ up to 1.7 $\times$ 10$^{15}$ M$_{\odot}$. To compare the kinematic properties between brightest g…
We present our study on the spatially resolved H_alpha and M_star relation for 536 star-forming and 424 quiescent galaxies taken from the MaNGA survey. We show that the star formation rate surface density (Sigma_SFR), derived based on the H_alpha emissions, is strongly correlated with the M_star surface density (Sigma_star) on kpc scales for star- forming galaxies and can be directly connected to the global star-forming sequence. This suggests that the global main sequence may be a consequence of a more fundamental relation on small scales. On the other hand, our result suggests that about 20%…
We report the discovery of RG1M0150, a massive, recently quenched galaxy at z=2.636 that is multiply imaged by the cluster MACSJ0150.3-1005. We derive a stellar mass of log M_*=11.49+0.10-0.16 and a half-light radius of R_e,maj =1.8+-0.4 kpc. Taking advantage of the lensing magnification, we are able to spatially resolve a remarkably massive yet compact quiescent galaxy at z>2 in ground-based near-infrared spectroscopic observations using Magellan/FIRE and Keck/MOSFIRE. We find no gradient in the strength of the Balmer absorption lines over 0.6 R_e - 1.6 R_e, which are consistent with an age o…
Spatially Resolved Physical Properties of Young Star Clusters and Star-forming Clumps in the Brightest z>6 Galaxy, the Strongly Lensed Cosmic Spear at z=6.2
Indiana University（印第安纳大学）；The Johns Hopkins University（约翰斯·霍普金斯大学）；Space Telescope Science Institute (STScI)（太空望远镜科学研究所）；Association of Universities for Research in Astronomy (AURA), Inc.（天体物理研究大学协会）；Northwestern University（西北大学）
Measuring stellar velocity dispersions of quiescent galaxies beyond $z\sim2$ is observationally challenging. Such measurements require near-infrared spectra with a continuum detection of at least moderate signal-to-noise, often necessitating long integrations. In this paper, we present deep X-Shooter spectroscopy of one of only two known gravitationally-lensed massive quiescent galaxies at $z>2$. This galaxy is quadruply imaged, with the brightest images magnified by a factor of $\sim5$. The total exposure time of our data is 9.8 hours on-source; however the magnification, and the slit placeme…
We report a massive quiescent galaxy at $z_{\rm spec}=3.0922^{+0.008}_{-0.004}$ spectroscopically confirmed at a protocluster in the SSA22 field by detecting the Balmer and Ca {\footnotesize II} absorption features with multi-object spectrometer for infrared exploration (MOSFIRE) on the Keck I telescope. This is the most distant quiescent galaxy confirmed in a protocluster to date. We fit the optical to mid-infrared photometry and spectrum simultaneously with spectral energy distribution (SED) models of parametric and nonparametric star formation histories (SFH). Both models fit the observed S…
Minor mergers are thought to be responsible for the size growth of quiescent field galaxies with decreasing redshift. We test this hypothesis using the cluster environment as a laboratory. Satellite galaxies in clusters move at high velocities, making mergers between them rare. The stellar mass-size relation in ten clusters and in the field is measured and compared at $z~\mathtt{\sim}~1$. Our cluster sample contains 344 spectroscopically-confirmed cluster members with Gemini/GMOS and 182 confirmed with HST WFC3 G141 grism spectroscopy. On average, quiescent and star-forming cluster galaxies ar…
Quiescent fractions in high-redshift galaxy groups reflect their hot-or-cold state of gas accretion
Université Paris-Saclay, CNRS, CEA（巴黎萨克雷大学，法国国家科学研究中心，法国原子能和替代能源委员会）；Instituto de Física, Pontificia Universidad Católica de Valparaíso（天主教瓦爾帕萊索大學物理研究所）；Cosmic Dawn Center (DAWN)（黎明宇宙中心）；DTU Space, Technical University of Denmark（丹麦技术大学空间研究所）
Using the novel $JWST$/NIRCam observations in the Abell 2744 field, we present a first spatially resolved overview of an $HST$-dark galaxy, spectroscopically confirmed at $z=2.58$ with magnification $μ\approx1.9$. While being largely invisible at $\sim$1 $μ$m with NIRCam, except for sparse clumpy sub-structures, the object is well-detected and resolved in the long-wavelength bands with a spiral shape clearly visible in F277W. By combining ancillary ALMA and $Herschel$ data, we infer that this object is an edge-on dusty spiral with an intrinsic stellar mass log$(M_*/M_\odot)\sim11.3$ and a dust…
We examine the role of environment on the in situ star formation (SF) hosted by the progenitors of the most massive galaxies in the present-day universe, the brightest cluster galaxies (BCGs), from $z \sim 3$ to present in the COSMOS field. Progenitors are selected from the COSMOS field using a stellar mass cut motivated by the evolving cumulative comoving number density of progenitors within the Illustris simulation, as well as the Millennium-II simulation and a constant comoving number density method for comparison. We characterize each progenitor using far-ultraviolet--far-infrared observat…
In this letter, we reconstruct the formation pathway of MRG-S0851, a massive, $\log M_*/M_\odot=11.02\pm0.04$, strongly lensed, red, galaxy at $z=1.883\pm0.001$. While the global photometry and spatially-resolved outskirts of MRG-S0851 imply an early-formation scenario with a slowly decreasing or constant star-formation history, a joint fit of 2D grism spectroscopy and photometry reveals a more complex scenario: MRG-S0851 is likely to be experiencing a centrally-concentrated rejuvenation in the inner $\sim$1 kpc in the last $\sim$100 Myr of evolution. We estimate $0.5\pm0.1\%$ of the total ste…
Brightest Cluster Galaxies (BCGs) are believed to have assembled most of their stars early in time and, therefore, should be passively evolving at low redshifts and appear "red-and-dead." However, there have been reports that a minority of low-redshift BCGs still have ongoing star formation rates (SFR) of a few to even $\sim$100 $M_\odot/yr$. Such BCGs are found in "cool-core" ("CC") clusters, and their star formation is thought to be fueled by "cooling flow." To further investigate the implications of low-redshift, star-forming BCGs, we perform a systematic search using the 22$μ$m data ("W4" …
Using spatially resolved spectroscopy from SDSS-IV MaNGA we have demonstrated that low ionisation emission line regions (LIERs) in local galaxies result from photoionisation by hot evolved stars, not active galactic nuclei. LIERs are ubiquitous in both quiescent galaxies and in the central regions of galaxies where star formation takes place at larger radii. We refer to these two classes of galaxies as extended LIER (eLIER) and central LIER (cLIER) galaxies respectively. cLIERs are late type galaxies located around the green valley, in the transition region between the star formation main sequ…
Brightest Cluster Galaxies (BCGs) might have been assembled relatively late (z<1) via mergers. By exploiting the high-resolution HST/ACS imaging, we find four BCGs (COSMOS-P 125516, 102810, 036694 and 089357) in major dry merging in 29 X-ray clusters at $0.3 \le z \le 0.6$ in the Cosmological Evolutionary Survey (COSMOS). These BCGs show prominent but quiescent double nuclei with a magnitude difference of $δm<1.5$ and a projected separation of $r_p<$ 10 kpc. Clear signatures of interaction such as extended plumes and/or significant asymmetries are also observed in their residual images. We inf…
Quiescent galaxies at $z \gtrsim 2$ are compact and have weak or absent emission lines, making it difficult to spatially resolve their kinematics and stellar populations using ground-based spectroscopy. Gravitationally lensed examples provide a promising route forward, but such objects are very rare. We describe a search in the fields of 232 galaxy clusters that has uncovered five bright ($H_{\rm AB} < 20$) lensed galaxies with red near-infrared colors. These include MRG-M0138, the brightest lensed galaxy known in the near-infrared. Analysis of near-infrared spectra and multiband photometry co…
We present the near-infrared high resolution imaging of an extremely dense group of galaxies at the core of the protocluster at $z=3.09$ in the SSA22 field by using the adaptive optics AO188 and the Infrared Camera and Spectrograph (IRCS) on Subaru Telescope. Wide morphological variety of them suggests their on-going dramatic evolutions. One of the two quiescent galaxies (QGs), the most massive one in the group, is a compact elliptical with an effective radius $r_{e} = 1.37\pm0.75$ kpc. It supports the two-phase formation scenario of giant ellipticals today that a massive compact elliptical is…
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 report the discovery of MAGAZ3NE J095924+022537, a spectroscopically-confirmed protocluster at $z = 3.3665^{+0.0009}_{-0.0012}$ around a spectroscopically-confirmed $UVJ$-quiescent ultra-massive galaxy (UMG; $M_{\star}=2.34^{+0.23}_{-0.34}\times10^{11} {\rm M}_\odot$) in the COSMOS UltraVISTA field. We present a total of 38 protocluster members (14 spectroscopic and 24 photometric), including the UMG. Notably, and in marked contrast to protoclusters previously reported at this epoch which have been found to contain predominantly star-forming members, we measure an elevated fraction of quies…
The colour-magnitude diagrams of resolved stellar populations are the best tool to study the star formation histories of the host galactic regions. In this review the method to derive star formation histories by means of synthetic colour-magnitude diagrams is briefly outlined, and the results of its application to resolved galaxies of various morphological types are summarized. It is shown that all the galaxies studied so far were already forming stars at the lookback time reached by the observational data, independently of morphological type and metallicity. Early-type galaxies have formed st…
One key problem in astrophysics is understanding how and why galaxies switch off their star formation, building the quiescent population that we observe in the local Universe. From the GAMA and VIPERS surveys, we use spectroscopic indices to select quiescent and candidate transition galaxies. We identify potentially rapidly transitioning post-starburst galaxies, and slower transitioning green-valley galaxies. Over the last 8 Gyrs the quiescent population has grown more slowly in number density at high masses (M$_*>10^{11}$M$_\odot$) than at intermediate masses (M$_*>10^{10.6}$M$_\odot$). There…
A big step forward with SHARP: spatially resolved stellar population properties in passive galaxies at z > 1.5
INAF - Istituto di Astrofisica Spaziale e Fisica Cosmica (IASF-Milano)（意大利国家天体物理研究所空间天体物理学与宇宙物理学研究所（米兰））；INAF - Osservatorio Astrofisico di Brera（意大利国家天体物理研究所布雷拉天文台）；INAF - Osservatorio Astrofisico di Arcetri（意大利国家天体物理研究所阿切尔奇天文台）
Brightest cluster galaxies (BCGs) are usually quiescent, but many exhibit star formation. Here we exploit the opportunity provided by rest-frame UV imaging of galaxy clusters in the CLASH (Cluster Lensing and Supernovae with Hubble) Multi-Cycle Treasury Project to reveal the diversity of UV morphologies in BCGs and to compare them with recent simulations of the cool, star-forming gas structures produced by precipitation-driven feedback. All of the CLASH BCGs are detected in the rest-frame UV (280 nm), regardless of their star-formation activity, because evolved stellar populations produce a mo…
We present a new method for tracing the evolution of BCGs from $z\sim 2$ to $z\sim 0$. We conclude on the basis of semi-analytical models that the best method to select BCG progenitors at $z\sim 2$ is a hybrid environmental density and stellar mass ranking approach. Ultimately we are able to retrieve 45\% of BCG progenitors. We apply this method on the CANDELS UDS data to construct a progenitor sample at high redshift. We furthermore populate the comparisons in local universe by using SDSS data with statistically likely contamination to ensure a fair comparison between high and low redshifts. …
Stellar kinematics provide insights into the masses and formation histories of galaxies. At high redshifts, spatially resolving the stellar kinematics of quiescent galaxies is challenging due to their compact sizes. Using deep near-infrared spectroscopy, we have measured the resolved stellar kinematics of four quiescent galaxies at z=1.95-2.64, introduced in Paper I, that are gravitationally lensed by galaxy clusters. Analyses of two of these have previously been reported individually by Newman et al. and Toft et al., and for the latter we present new observations. All four galaxies show signi…
A Spatially Resolved Evolutionary Sequence of Multi-wavelength AGN Host Galaxies
Max Planck Institute for Astrophysics（马克斯·普朗克天体物理学研究所）；Chinese Academy of Sciences South America Center for Astronomy, National Astronomical Observatories, CAS（中国科学院南美天文中心，国家天文台，中国科学院）；Institute for Astronomy, University of Edinburgh（爱丁堡大学天体物理研究所）；Leiden Observatory, Leiden University（莱顿大学莱顿天文台）；Department of Physics, Astronomy and Mathematics, University of Hertfordshire（赫特福德大学物理、天文与数学系）
Dust-enshrouded, starbursting, submillimeter galaxies (SMGs) at $z \geq 3$ have been proposed as progenitors of $z \geq 2$ compact quiescent galaxies (cQGs). To test this connection, we present a detailed spatially resolved study of the stars, dust and stellar mass in a sample of six submillimeter-bright starburst galaxies at $z \sim 4.5$. The stellar UV emission probed by HST is extended, irregular and shows evidence of multiple components. Informed by HST, we deblend Spitzer/IRAC data at rest-frame optical finding that the systems are undergoing minor mergers, with a typical stellar mass rat…
We present a sample of 34 spectroscopically confirmed BzK-selected ~1e11 Msun quiescent galaxies (pBzK) in the COSMOS field. The targets were initially observed with VIMOS on the VLT to facilitate the calibration of the photometric redshifts of massive galaxies at z >~ 1.5. Here we describe the reduction and analysis of the data, and the spectrophotometric properties of these pBzK galaxies. In particular, using a spatially resolved median 2D spectrum, we find that the fraction of stellar populations with ages <1 Gyr is at least 3 times higher in the outer regions of the pBzK galaxies than in t…
We present results from modeling the optical spectra of a large sample of quiescent galaxies between 0.1 < z < 0.7 from the Sloan Digital Sky Survey (SDSS) and the AGN and Galaxy Evolution Survey (AGES). We examine how the stellar ages and abundance patterns of galaxies evolve over time as a function of stellar mass from 10^{9.6}-10^{11.8} Msun. Galaxy spectra are stacked in bins of mass and redshift, and modeled over a wavelength range from 4000 A to 5500 A. Full spectrum stellar population synthesis modeling provides estimates of the age and the abundances of the elements Fe, Mg, C, N, and C…
Around the turn of the last century, star clusters of all kinds were considered "simple" stellar populations. Over the past decade, this situation has changed dramatically. At the same time, star clusters are among the brightest stellar population components and, as such, they are visible out to much greater distances than individual stars, even the brightest, so that understanding the intricacies of star cluster composition and their evolution is imperative for understanding stellar populations and the evolution of galaxies as a whole. In this review of where the field has moved to in recent …
We present the velocity dispersion measurements of four massive $\sim10^{11}M_\odot$ quiescent galaxies at $3.2 < z < 3.7$ based on deep H and K$-$band spectra using the Keck/MOSFIRE near-infrared spectrograph. We find high velocity dispersions of order $σ_e\sim250$ km/s based on strong Balmer absorption lines and combine these with size measurements based on HST/WFC3 F160W imaging to infer dynamical masses. The velocity dispersion are broadly consistent with the high stellar masses and small sizes. Together with evidence for quiescent stellar populations, the spectra confirm the existence of …
The most evident features of colour-magnitude diagrams of galaxies are the red sequence of quiescent galaxies, extending up to the brightest elliptical galaxies, and the blue cloud of star-forming galaxies, which is truncated at a luminosity L~L*. The truncation of the blue cloud indicates that in the most massive systems star formation must be quenched. For this to happen the virial-temperature galactic gas must be kept hot and any accreted cold gas must be heated. The elimination of accreted cold gas can be due to thermal evaporation by the hot interstellar medium, which in turn is prevented…
We analyse the spatially-resolved stellar populations of 9 local ($z<0.1$) Brightest Cluster Galaxies (BCGs) observed with VIMOS in IFU mode. Our sample is composed of 7 slow-rotating and 2 fast-rotating BCGs. We do not find a connection between stellar kinematics and stellar populations in this small sample. The BCGs have shallow metallicity gradients (median $Δ$[Fe/H] $= -0.11\pm0.1$), high central metallicities (median $[$Fe/H]$_{[α/Fe]=0} = 0.13\pm0.07$), and a wide range of central ages (from 5 to 15 Gyr). We propose that the reason for this is diverse evolutionary paths in BCGs. 67 per c…
We performed a detailed study of the evolution of the star formation rate (SFR) and stellar mass of the brightest group galaxies (BGGs) and their relative contribution to the total baryon budget within $R_{200}$ ($f^{BGG}_{b,200}$). The sample comprises 407 BGGs selected from X-ray galaxy groups ($M_{200}=10^{12.8}-10^{14} \;M_{\odot}$) out to $z\sim1.3$ identified in the COSMOS, XMM-LSS, and AEGIS fields. We find that BGGs constitute two distinct populations of quiescent and star-forming galaxies and their mean SFR is $\sim2$ dex higher than the median SFR at $ z<1.3 $. Both the mean and the …
We present well-resolved near-IR and sub-mm analysis of the three highly star-forming massive ($>10^{11}\,\rm M_{\odot}$) galaxies within the core of the RO-1001 galaxy group at $\rm z=2.91$. Each of them displays kpc-scale compact star-bursting cores with properties consistent with forming galaxy bulges, embedded at the center of extended, massive stellar disks. Surprisingly, the stellar disks are unambiguously both quiescent, and severely lopsided. Therefore, `outside-in' quenching is ongoing in the three group galaxies. We propose an overall scenario in which the strong mass lopsidedness in…
We present spatially-resolved Atacama Large Millimeter/sub-millimeter Array (ALMA) 870 $μ$m dust continuum maps of six massive, compact, dusty star-forming galaxies (SFGs) at $z\sim2.5$. These galaxies are selected for their small rest-frame optical sizes ($r_{\rm e, F160W}\sim1.6$ kpc) and high stellar-mass densities that suggest that they are direct progenitors of compact quiescent galaxies at $z\sim2$. The deep observations yield high far-infrared (FIR) luminosities of L$_{\rm IR}=10^{12.3-12.8}$ L$_{\odot}$ and star formation rates (SFRs) of SFR$=200-700$ M$_{\odot}$yr$^{-1}$, consistent w…
Post-starburst galaxies (PSBs) have recently and rapidly quenched their star-formation, thus they are an important way to understand how galaxies transition from star-forming late-types to quiescent early-types. The recent discovery of large cold gas reservoirs in PSBs calls into question the theory that galaxies must lose their gas to become quiescent. Optical Integral Field Spectroscopy (IFS) surveys have revealed two classes of PSBs: central PSBs with central quenching regions and ring PSBs with quenching in their outskirts. We analyze a sample of 13 nearby (z < 0.1) PSBs with spatially res…
We introduce an ALMA band 3 spectroscopic survey, targeting the brightest submillimeter galaxies (SMGs) in the COSMOS field. Here we present the first results based on the 18 primary SMGs that have 870 $μ$m flux densities of $S_{870}=12.4-19.3$ mJy and are drawn from a parent sample of 260 ALMA-detected SMGs from the AS2COSMOS survey. We detect emission lines in 17 and determine their redshifts to be in the range of $z=2-5$ with a median of ${3.3\pm0.3}$. We confirm that SMGs with brighter $S_{870}$ are located at higher redshifts. The data additionally cover five fainter companion SMGs, and w…
We use stellar and dynamical mass profiles, combined with a stellar population analysis, of 32 brightest cluster galaxies (BCGs) at redshifts of 0.05 $\leq z \leq$ 0.30, to place constraints on their stellar Initial Mass Function (IMF). We measure the spatially-resolved stellar population properties of the BCGs, and use it to derive their stellar mass-to-light ratios ($Υ_{\star \rm POP}$). We find young stellar populations ($<$200 Myr) in the centres of 22 per cent of the sample, and constant $Υ_{\star \rm POP}$ within 15 kpc for 60 per cent of the sample. We further use the stellar mass-to-li…
