A Consistent Comparison of Intracluster Light Assembly in Simulations I. Redshift Evolution and Progenitor Galaxies
University of Nottingham（诺丁汉大学）；École Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院）；Universidad Autónoma de Madrid（马德里自治大学）；Royal Observatory, Edinburgh（爱丁堡皇家天文台）
Harley J. Brown, Garreth Martin, Frazer R. Pearce, Yannick M. Bahé, Joseph Butler, Weiguang Cui, Nina A. Hatch, Alexander Knebe
备注：
25 pages, 14 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society
The tidal stripping of satellite galaxies and the stellar detritus ejected during galaxy mergers builds up a diffuse stellar component in galaxy clusters known as the intracluster light (ICL). We investigate ICL assembly in cluster-mass haloes ($M_{178c}\sim10^{14}-10^{15}$ M$_\odot$) using four different hydrodynamical simulations (Horizon-AGN, TNG100, The Three Hundred Gizmo-Simba 7K, and Hydrangea) under a homogenized ICL identification framework. For our fiducial ICL definition we obtain broadly consistent $z\approx0$ ICL stellar mass fractions ($\sim0.1-0.2$) and, by tracking the progenitors of $z\approx0$ clusters back to $z\gtrsim2$, find no significant evolution in average ICL mass fractions. Alternative approaches for distinguishing the ICL from the central galaxy show the absolute ICL fraction to be highly sensitive to adopted definition, but we never find any significant inter-simulation discrepancies when implementing a consistent methodology to identify the ICL. Whether the average ICL mass fraction falls with increasing redshift or does not evolve is determined by the ICL definition adopted. By tracing $z\approx0$ ICL stars back to their progenitor galaxies, we find that lower-mass satellites typically make slightly larger ICL contributions relative to their mass in every considered simulation, but which galaxies make the dominant contribution to the ICL is primarily controlled by the infalling satellite mass function. Most ICL stars sourced from satellite galaxies are therefore expected to originate from galaxies with infall stellar masses above $\sim10^{10}$ M$_\odot$ and largely within $10^{10.5}-10^{11.5}$ M$_\odot$.
We investigate the formation channels of the intracluster light (ICL) and the brightest cluster galaxy (BCG) in clusters at $z=0$. For this, we perform multi-resolution cosmological N-body simulations using the "Galaxy Replacement Technique" (GRT). We study the formation channels of the ICL and BCG as a function of distance from the cluster center and the dynamical state of the clusters at $z=0$. To do this, we trace back the stars of the ICL and BCG, and identify the stellar components in which they existed when they first fell into the clusters. We find that the progenitors of the ICL and BC…
Both simulations and observations have shown that turbulence is a pervasive phenomenon in cosmic scenarios, yet it is particularly difficult to model numerically due to its intrinsically multiscale character which demands high resolutions. Additionally, turbulence is tightly connected to the dynamical state and the formation history of galaxies and galaxy clusters, producing a diverse phenomenlogy which requires large samples of such structures to attain robust conclusions. In this work, we use an adaptive mesh refinement (AMR) cosmological simulation to explore the generation and dissipation …
The diffuse extended outer regions of galaxies are hard to study because they are faint, with typical surface brightness of 1% of the dark night sky. We can tackle this problem by using resolved star tracers which remain visible at large distances from the galaxy centres. This article describes the use of Planetary Nebulae as tracers and the calibration of their properties as indicators of the star formation history, mean age and metallicity of the parent stars in the Milky Way and Local Group galaxies . We then report on the results from a deep, extended, planetary nebulae survey in a 0.5 sqd…
Intracluster stars are believed to be unbound from their progenitor galaxies and diffused throughout the galaxy cluster, creating intracluster light (ICL). However, when and how these stars form are still in debate. To directly constrain the origin, one powerful method is to study clusters at the epoch when mature galaxy clusters began to appear. We report measurements of the spatial distribution, color, and quantity of diffuse intracluster stars for a massive galaxy cluster at a redshift of 1.24. This is the most distant galaxy cluster to date for which those three properties of the ICL have …
The diffuse light in clusters of galaxies, or intracluster light, has attracted a lot of attention lately due to its potential in describing the assembly history of galaxy clusters and to explain the observed growth of the brightest cluster galaxy with time. The properties of this light (color, stellar populations, extent) give clues about its formation and, consequently, the processes that shape the cluster. Here, I will present a review on intracluster light, its history, properties and the particular observational problems and limitations associated with the study of this diffuse component …
We analyse the mass assembly of central galaxies in the EAGLE hydrodynamical simulations. We build merger trees to connect galaxies to their progenitors at different redshifts and characterize their assembly histories by focusing on the time when half of the galaxy stellar mass was assembled into the main progenitor. We show that galaxies with stellar mass $M_*<10^{10.5}M_{\odot}$ assemble most of their stellar mass through star formation in the main progenitor (`in-situ' star formation). This can be understood as a consequence of the steep rise in star formation efficiency with halo mass for …
Globular clusters (GCs) are thought to be ancient relics from the early formative phase of galaxies, although their physical origin remains uncertain. GCs are most numerous around massive elliptical galaxies, where they can exhibit a broad colour dispersion, suggesting a wide metallicity spread. Here, we show that many thousands of compact and massive (~5$\times$10$^{\rm 3}-$3$\times$ 10$^{\rm 6} M_{\odot}$) star clusters have formed at an approximately steady rate over, at least, the past ~1Gyr around NGC 1275, the central giant elliptical galaxy of the Perseus cluster. Beyond ~1Gyr, these st…
On the Origin of Intracluster Light based on the High-resolution Simulation, NewCluster
Yonsei University（延世大学）；Sorbonne Université（索邦大学）；CNRS（法国国家科学研究中心）；University of Nottingham（诺丁汉大学）；Korea Institute for Advanced Study（韩国高等研究院）；Korea Astronomy and Space Science Institute（韩国天文学与空间科学研究所）
EDGE-INFERNO: The chemical signatures of assembly history in reionization fossils
American Museum of Natural History（美国自然历史博物馆）；University of Bath（巴斯大学）；University of Chicago（芝加哥大学）；Kavli Institute for Cosmological Physics, University of Chicago（芝加哥大学卡弗里宇宙学物理研究所）；NSF-Simons AI Institute for the Sky (SkAI)（NSF-Simons 天空人工智能研究所 (SkAI)）；University of Surrey（萨里大学）；Lund University（隆德大学）；Carnegie Observatories（卡内基观测站）；Carnegie Theoretical Astrophysics Center, Carnegie Observatories（卡内基观测站卡内基理论天体物理学中心）；Columbia University（哥伦比亚大学）；Center for Astrophysics | Harvard & Smithsonian（哈佛-史密森尼天体物理中心）
Intracluster globular clusters as tracers of the mass assembly of the Hydra I galaxy cluster
European Southern Observatory（欧洲南方天文台）；Universitätssternwarte der Ludwig-Maximilians Universität（路德维希-马克西米利安大学大学天文台）；INAF – Astronomical Observatory of Capodimonte（意大利国家天体物理研究所卡波迪蒙特天文台）；Max-Planck-Institut für Extraterrestrische Physik（马克斯·普朗克地外物理学研究所）；INAF – Astronomical Observatory of Abruzzo（意大利国家天体物理研究所阿布鲁佐天文台）；Gran Sasso Science Institute（格兰萨索科学研究所）
Nearly all intragroup (IGL) and intracluster light (ICL) comes from stars that are not bound to any single galaxy but were formed in galaxies and later unbound from them. In this review we focus on the physical properties - phase space properties, metallicity and age distribution - of the ICL and IGL components of the groups and clusters in the local universe, within 100 Mpc distance. Kinematic information on these very low surface brightness structures mostly comes from discrete tracers such as planetary nebulae and globular clusters, showing highly unrelaxed velocity distributions. Cosmologi…
We study the relationship between the morphology and star formation history (SFH) of 361 quiescent galaxies (QGs) at redshift $\langle z_{obs}\rangle\approx 2$, with stellar mass $\log M_*\ge10.3$, selected with the UVJ technique. Taking advantage of panchromatic photometry covering the rest-frame UV-to-NIR spectral range ($\approx40$ bands), we reconstruct the non-parametric SFH of the galaxies with the fully Bayesian SED fitting code Prospector. We find that the half-light radius $R_e$, observed at $z_{obs}$, depends on the formation redshift of the galaxies, $z_{form}$, and that this relati…
As endpoints of the hierarchical mass-assembly process, the stellar populations of local early-type galaxies encode the assembly history of galaxies over cosmic time. We use Horizon-AGN, a cosmological hydrodynamical simulation, to study the merger histories of local early-type galaxies and track how the morphological mix of their progenitors evolves over time. We provide a framework for alleviating `progenitor bias' -- the bias that occurs if one uses only early-type galaxies to study the progenitor population. Early-types attain their final morphology at relatively early epochs -- by $z\sim1…
We use Hubble Space Telescope (HST) imaging and near-infrared spectroscopy from Keck/MOSFIRE to study the sub-structure around the progenitor of a Milky Way-mass galaxy in the Hubble Frontier Fields (HFF). Specifically, we study an $r_e = 40^{+70}_{-30}$pc, $M_{\star} \sim 10^{8.2} M_{\odot}$ rest-frame ultra-violet luminous "clump" at a projected distance of $\sim$100~pc from a $M_{\star} \sim 10^{9.8}$M$_{\odot}$ galaxy at $z = 2.36$ with a magnification $μ= 5.21$. We measure the star formation history of the clump and galaxy by jointly modeling the broadband spectral energy distribution fro…
Intracluster light and dark matter halo shapes reflect common assembly, not mutual coupling: shape correspondence in CDM but not SIDM
School of Physics & Astronomy, University of Nottingham（诺丁汉大学物理与天文学院）；Universidad Autónoma de Madrid（马德里自治大学）；Centro de Investigación Avanzada en Física Fundamental (CIAFF), Facultad de Ciencias, Universidad Autónoma de Madrid（马德里自治大学理学院基础物理前沿研究中心）；Institute for Astronomy, Royal Observatory, Edinburgh（爱丁堡皇家天文台天体物理研究所）；Laboratoire d’Astrophysique, École Polytechnique Fédérale de Lausanne (EPFL)（洛桑联邦理工学院天体物理实验室）；Donostia International Physics Center (DIPC)（圣塞巴斯蒂安国际物理中心）；Institute of Space Sciences (ICE, CSIC)（空间科学研究所（加泰罗尼亚高等研究理事会））
We present a survey of globular clusters (GCs) in the massive gravitational lens cluster SMACS J0723.3-7327 at $z=0.39$ based on the early released JWST/NIRCam images. In the color-magnitude diagrams of the point sources we find clearly a rich population of intracluster GCs that spread in a wide area of the cluster. Their ages, considering the cluster redshift, are younger than 9.5 Gyr. The F200W (AB) magnitudes of these GCs, $26.5<{F200W_0} <29.5$ mag, correspond to $-15.2<{M_{F200W}} <-12.2$ mag, showing that they belong to the brightest GCs (including ultracompact dwarfs). The spatial distr…
In this paper, we use stacking analysis to trace the mass-growth, colour evolution, and structural evolution of present-day massive galaxies ($\log(M_{*}/M_{\odot})=11.5$) out to $z=5$. We utilize the exceptional depth and area of the latest UltraVISTA data release, combined with the depth and unparalleled seeing of CANDELS to gather a large, mass-selected sample of galaxies in the NIR (rest-frame optical to UV). Progenitors of present-day massive galaxies are identified via an evolving cumulative number density selection, which accounts for the effects of merging to correct for the systematic…
Massive star clusters are observed in a broad range of galaxy luminosity and types, and are assumed to form in dense gas-rich environments. Using a parsec-resolution hydrodynamical simulation of an isolated gas-rich low mass galaxy, we discuss here the non-linear effects of stellar feedback on the properties of star clusters with a focus on the progenitors of nuclear clusters. Our simulation shows two categories of star clusters: those for which feedback expels gas leftovers associated with their formation sites, and those, in a denser environment around which feedback fails at totally clearin…
ELUCID. IX. Recovering the Substructures and History of the Coma Cluster
University of Science and Technology of China（中国科学技术大学）；Universidad Autónoma de Madrid（马德里自治大学）；University of Edinburgh（爱丁堡大学）；Shanghai Jiao Tong University（上海交通大学）；Sun Yat-sen University（中山大学）；University of Massachusetts（马萨诸塞大学）
The search for the progenitors to today's fossil galaxy systems has been restricted to N-body simulations until recently, where 12 fossil progenitors were identified in the CASSOWARY catalog of strong lensing systems. All 12 systems lie in the predicted redshift range for finding fossils in mid brightest group galaxy (BGG) assembly, and all show complex merging environments at their centers. None of these progenitors had archival X-ray data, and many were lacking high resolution optical data making precision photometry extremely difficult. Here, we present Chandra and Hubble Space Telescope (H…
We investigate the role of supernova (SN)-driven galactic winds in the chemical enrichment of the intracluster medium (ICM). Such outflows on galactic scales have their origin in huge star forming regions and expel metal enriched material out of the galaxies into their surroundings as observed, for example, in the nearby starburst galaxy NGC 253. As massive stars in OB-associations explode sequentially, shock waves are driven into the interstellar medium (ISM) of a galaxy and merge, forming a superbubble (SB). These SBs expand in a direction perpendicular to the disk plane following the densit…
We simulate the phase-space distribution of stellar mass in 9 massive Lambda-CDM galaxy clusters by applying the semi-analytic particle tagging method of Cooper et al. to the Phoenix suite of high-resolution N-body simulations (M200 = 7.5 to 33 x 10^14 Msol). The resulting surface brightness (SB) profiles of brightest cluster galaxies (BCGs) match well to observations. On average, stars formed in galaxies accreted by the BCG account for ~90 per cent of its total mass (the remainder is formed in situ). In circular BCG-centred apertures, the superposition of multiple debris clouds (each ~10 per …
With Hubble Space Telescope imaging, we investigate the progenitor population and formation mechanisms of the intracluster light (ICL) for 23 galaxy groups and clusters ranging from 3$\times10^{13}<$M$_{500,c}$ [M$_\odot$]$<9\times10^{14}$ at 0.29$<$z$<$0.89. The color gradients of the BCG+ICL become bluer with increasing radius out to 53-100 kpc for all but one system, suggesting that violent relaxation after major mergers with the BCG cannot be the dominant source of ICL. For clusters the BCG+ICL luminosity at r$<$100 kpc (0.08-0.13 r$_{500,c}$) is 1.2-3.5$\times 10^{12}$L$_\odot$; for the g…
We investigate the absorption features associated with a gas-rich dwarf galaxy using cosmological hydrodynamics simulations. Our goal is to explore whether the progenitors of the lowest mass dwarf galaxies known to harbor neutral hydrogen today (M_star~10^6 solar mass, M_halo=4x10^9 solar mass) could possibly be detected as Damped Lyman-alpha Absorbers (DLAs) over cosmic time. We trace the evolution of a single dwarf galaxy, pre-selected to contain DLAs, from the era of the first metal-free, so-called Population~III (Pop~III), stars, down to z=0, thus allowing us to study the metal enrichment …
Galaxy clusters are the most massive gravitationally bound structures in the Universe, comprising thousands of galaxies and pervaded by a diffuse, hot ``intracluster medium'' (ICM) that dominates the baryonic content of these systems. The formation and evolution of the ICM across cosmic time is thought to be driven by the continuous accretion of matter from the large-scale filamentary surroundings and dramatic merger events with other clusters or groups. Until now, however, direct observations of the intracluster gas have been limited only to mature clusters in the latter three-quarters of the…
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. …
We study the formation of over 6000 compact groups (CGs) of galaxies identified in mock redshift-space galaxy catalogues built from semi-analytical models of galaxy formation (SAMs) run on the Millennium Simulations. We select CGs of 4 members in our mock SDSS galaxy catalogues and, for each CG, we trace back in time the real-space positions of the most massive progenitors of their 4 galaxies. By analysing the evolution of the distance of the galaxy members to the centre of mass of the group, we identify 4 channels of CG formation. The classification of these assembly channels is performed wit…
Dark and Luminous Matter in the Coma Cluster: Probing Galaxy Cluster Assembly Through Filaments with Weak Lensing and Multiwavelength Observations
Duke University（杜克大学）；Yonsei University（延世大学）；California Institute of Technology（加州理工学院）；University of California, Davis（加利福尼亚大学戴维斯分校）；Instituto de Astrofísica de Andalucía–CSIC（安达卢西亚天体物理研究所-西班牙国家研究委员会）；Observatório Nacional（国家天文台）；University of Chicago（芝加哥大学）；Seoul National University（首尔国立大学）
We constrain the evolution of the brightest cluster galaxy plus intracluster light (BCG+ICL) using an ensemble of 42 galaxy groups and clusters that span redshifts of z = 0.05-1.75 and masses of $M_{500,c}=2\times10^{13}-10^{15}$ M$_\odot$ Specifically, we measure the relationship between the BCG+ICL stellar mass $M_\star$ and $M_{500,c}$ at projected radii 10 < r < 100 kpc for three different epochs. At intermediate redshift (z = 0.40), where we have the best data, we find $M_\star\propto M_{500,c}^{0.48\pm0.06}$. Fixing the exponent of this power law for all redshifts, we constrain the norma…
The stellar content of the intracluster light (ICL) provides unique insight into the hierarchical assembly process of galaxy clusters.However, the ICL is difficult to study due to its low surface brightness and large physical extent. We present optical spectra of three ICL regions in the Coma cluster, located between 100-180kpc from their nearest BCGs: NGC4889 and NGC4874. The mean surface brightness of the three ICL regions are μ$_g$~25.3-26.2mag arcsec$^{-2}$. IFU spectroscopy with 13.5 hr on-source integration time were acquired as part of an ancillary program within the SDSS-IV MaNGA surve…
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…
We present a pilot study on the origin and assembly history of the ICL for four galaxy clusters at 0.44<z<0.57 observed with the Hubble Space Telescope from the Cluster Lensing and Supernova Survey with Hubble (CLASH) sample. Using this sample of clusters we set an empirical limit on the amount of scatter in ICL surface brightness profiles of such clusters at z=0.5 and constrain the progenitor population and formation mechanism of the ICL by measuring the ICL surface brightness profile, the ICL color and color gradient, and the total ICL luminosity within 10<r<110 kpc. The observed scatter is …
Globular clusters (GCs) are powerful tracers of the galaxy assembly process, and have already been used to obtain a detailed picture of the progenitors of the Milky Way. Using the E-MOSAICS cosmological simulation of a (34.4 Mpc)$^3$ volume that follows the formation and co-evolution of galaxies and their star cluster populations, we develop a method to link the origin of GCs to their observable properties. We capture this complex link using a supervised deep learning algorithm trained on the simulations, and predict the origin of individual GCs (whether they formed in the main progenitor or w…
The formation and evolutionary processes of galaxy bulges are still unclear, and the presence of young stars in the bulge of the Milky Way is largely debated. We recently demonstrated that Terzan 5, in the Galactic bulge, is a complex stellar system hosting stars with very different ages and a striking chemical similarity to the field population. This indicates that its progenitor was likely one of the giant structures that are thought to generate bulges through coalescence. Here we show that another globular cluster-like system in the bulge (Liller 1) hosts two distinct stellar populations wi…
Most detected neutral atomic hydrogen (HI) at low redshift is associated with optically bright galaxies. However, a handful of HI clouds are known which appear to be optically dark and have no nearby potential progenitor galaxies, making tidal debris an unlikely explanation. In particular, 6 clouds identified by the Arecibo Galaxy Environment Survey are interesting due to the combination of their small size, isolation, and especially their broad line widths atypical of other such clouds. A recent suggestion is that these clouds exist in pressure equilibrium with the intracluster medium, with t…
We present 25 cosmological zoom-in simulations of Milky Way-mass galaxies in the `MOdelling Star cluster population Assembly In Cosmological Simulations within EAGLE' (E-MOSAICS) project. E-MOSAICS couples a detailed physical model for the formation, evolution, and disruption of star clusters to the EAGLE galaxy formation simulations. This enables following the co-formation and co-evolution of galaxies and their star cluster populations, thus realising the long-standing promise of using globular clusters (GCs) as tracers of galaxy formation and assembly. The simulations show that the age-metal…
We use high-resolution, multi-band imaging of ~16,500 galaxies in the CANDELS fields at 0 < z < 2.5 to study the evolution of color gradients and half-mass radii over cosmic time. We find that galaxy color gradients at fixed mass evolve rapidly between z~2.5 and z~1, but remain roughly constant below z~1. This result implies that the sizes of both star-forming and quiescent galaxies increase much more slowly than previous studies found using half-light radii. The half-mass radius evolution of quiescent galaxies is fully consistent with a model which uses observed minor merger rates to predict …
Cluster Ages to Reconstruct the Milky Way Assembly (CARMA). II. The age-metallicity relation of Gaia-Sausage-Enceladus globular clusters
Universidade de Vigo（维戈大学）；Universidad de La Laguna（拉古纳大学）；INAF - Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（博洛尼亚天文物理与空间科学研究所）；INAF – Osservatorio Astronomico di Roma（罗马天文台）；INAF – Osservatorio Astronomico di Abruzzo（阿布鲁佐天文台）；INFN - Sezione di Pisa, Universitá di Pisa（比萨大学及意大利国家核物理研究所比萨分部）；Instituto de Astrofísica de Canarias（加那利群岛天体物理学研究所）；Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna（博洛尼亚大学物理与天文学系）；Universidad de Granada（格拉纳达大学）
We analyze the stellar growth of Brightest Cluster Galaxies (BCGs) produced by cosmological zoom-in hydrodynamical simulations of the formation of massive galaxy clusters. The evolution of the stellar mass content is studied considering different apertures, and tracking backwards either the main progenitor of the $z=0$ BCG or that of the cluster hosting the BCG at $z=0$. Both methods lead to similar results up to $z \simeq 1.5$. The simulated BCGs masses at $z=0$ are in agreement with recent observations. In the redshift interval from $z=1$ to $z=0$ we find growth factors 1.3, 1.6 and 3.6 for …
Cosmological simulations of galaxy formation can produce present-day galaxies with a large range of assembly and star formation histories. A detailed study of the metallicity evolution and star formation history of such simulations can assist in predicting LIGO-detectable compact object binary mergers. Recent simulations of compact binary evolution suggest the compact object merger rate depends sensitively on the progenitor's metallicity. Rare low-metallicity star formation during galaxy assembly can produce more detected compact binaries than typical star formation. Using detailed simulations…
Understanding the formation history of brightest cluster galaxies is an important topic in galaxy formation. Utilizing the Planck Sunyaev-Zel'dovich cluster catalog, and applying the Ansatz that the most massive halos at one redshift remain among the most massive ones at a slightly later cosmic epoch, we have constructed cluster samples at redshift z~0.4 and z~0.2 that can be statistically regarded as progenitor-descendant pairs. This allows us to study the stellar mass assembly history of BCGs in these massive clusters at late times, finding the degree of growth between the two epochs is like…
Cluster Ages to Reconstruct the Milky Way Assembly (CARMA). V. The chronological merger tree of the Milky Way
Universidade de Vigo（维戈大学）；Universidad de La Laguna（拉古纳大学）；INAF - Osservatorio di Astrofisica e Scienza dello Spazio di Bologna（意大利国家天体物理研究所博洛尼亚天文与空间科学观测站）；Università degli Studi di Bologna（博洛尼亚大学）；INAF – Osservatorio Astronomico di Abruzzo（意大利国家天体物理研究所阿布鲁佐天文台）；INFN - Sezione di Pisa, Universitá di Pisa（意大利国家核物理研究所比萨分部，比萨大学）；Instituto de Astrofísica de Canarias（加那利天体物理学研究所）
Super star clusters are the end product of star formation under the most extreme conditions. As such, studying how their final stellar populations are assembled from their natal progenitor gas clouds can provide strong constraints on star formation theories. An obvious place to look for the initial conditions of such extreme stellar clusters are gas clouds of comparable mass and density, with no star formation activity. We present a method to identify such progenitor gas clouds and demonstrate the technique for the gas in the inner few hundred pc of our Galaxy. The method highlights three clou…
