Globular clusters as tracers of the dark matter halo: insights from the E-MOSAICS simulations
Marta Reina-Campos, Sebastian Trujillo-Gomez, Alis J. Deason, J. M. Diederik Kruijssen, Joel L. Pfeffer, Robert A. Crain, Nate Bastian, Meghan E. Hughes
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19 pages, 11 figures and 2 tables; submitted to MNRAS, comments and/or suggestions are welcomed!
Globular clusters (GCs) are bright objects that span a wide range of galactocentric distances, and are thus probes of the structure of dark matter (DM) haloes. In this work, we explore whether the projected radial profiles of GCs can be used to infer the structural properties of their host DM haloes. We use the simulated GC populations in a sample of 166 central galaxies from the $(34.4~\rm cMpc)^3$ periodic volume of the E-MOSAICS project. We find that more massive galaxies host stellar and GC populations with shallower density profiles that are more radially extended. In addition, the metal-poor GC subpopulations tend to have shallower and more extended profiles than the metal-rich subsamples, which we relate to the preferentially accreted origin of the metal-poor GCs. We find strong correlations between the slopes and effective radii of the radial profiles of the GC populations and the structural properties of the DM haloes, such as their power-law slopes, scale radii, and concentration parameters. Accounting for a dependence on the galaxy stellar mass decreases the scatter of the two-dimensional relations. This suggests that the projected number counts of GCs, combined with their galaxy mass, trace the density profile of the DM halo of their host galaxy. When applied to extragalactic GC systems, we recover the scale radii and the extent of the DM haloes of a sample of ETGs with uncertainties smaller than $0.2~\rm dex$. Thus, extragalactic GC systems provide a novel avenue to explore the structure of DM haloes beyond the Local Group.
The [α/Fe]-[Fe/H] relation in the E-MOSAICS simulations: its connection to the birth place of globular clusters and the fraction of globular cluster field stars in the bulge
The metallicity distributions of globular cluster (GC) systems in galaxies are a critical test of any GC formation scenario. In this work, we investigate the predicted GC metallicity distributions of galaxies in the MOdelling Star cluster population Assembly In Cosmological Simulations within EAGLE (E-MOSAICS) simulation of a representative cosmological volume ($L = 34.4$ comoving Mpc). We find that the predicted GC metallicity distributions and median metallicities from the fiducial E-MOSAICS GC formation model agree well the observed distributions, except for galaxies with masses $M_\ast \si…
We set out to compare the age-metallicity relation (AMR) of massive clusters from Magellanic Cloud mass galaxies in the E-MOSAICS suite of numerical cosmological simulations with an amalgamation of observational data of massive clusters in the Large and Small Magellanic Clouds (LMC/SMC). We aim to test if: i) star cluster formation proceeds according to universal physical processes, suggestive of a common formation mechanism for young-massive clusters (YMCs), intermediate-age clusters (IACs), and ancient globular clusters (GCs); ii) massive clusters of all ages trace a continuous AMR; iii) the…
The E-MOSAICS project: tracing galaxy formation and assembly with the age-metallicity distribution of globular clusters
我们提出了25个宇宙学放大模拟银河系质量的星系在“建模星团人口大会在宇宙学模拟内鹰”(E-MOSAICS)项目。E-MOSAICS将星团形成、演化和分裂的详细物理模型与EAGLE星系形成模拟相结合。这使得以下的共同形成和共同进化的星系和他们的星团人口,从而实现了长期的承诺,使用球状星团(GC)作为示踪剂的星系形成和组装。模拟结果表明,年龄金属丰度分布的GC人口表现出强烈的星系到星系的变化,导致其演化历史的差异。我们开发了一种形式主义,系统地限制使用GC年龄金属丰度分布星系的组装历史。这些分布的特点是通过13个指标,我们相关的30个数量描述星系形成和组装(如晕属性,形成/组装红移,恒星质量组装时间尺度,星系合并统计),导致20个统计(高度)显着的相关性。GC年龄-金属丰度分布是研究主星系质量增长、金属富集和次合并历史的灵敏探针。没有这样的关系被发现之间的GC和主要的合并,发挥了次主导作用的银河系质量的星系GC的形成。最后,我们展示了GC年龄金属丰度分布如何使宿主星系的合并树的重建,使我们能够确定所有的祖先与质量$M_*\gtrsim10^8$ M $_\odot$的红移$1\leq z\leq2.5$。这些结果表明,宇宙学模拟的共同形成和共同演化的GC和他们的宿主星系成功地解锁的潜力GC作为定量示踪剂的星系形成和组装。
Linking globular clusters (GCs) to the assembly of their host galaxies is an overarching goal in GC studies. The inference of tight scaling relations between GC system properties and the mass of both the stellar and dark halo components of their host galaxies are indicative of an intimate physical connection, yet have also raised fundamental questions about how and when GCs form. Specifically, the inferred correlation between the mass of a GC system (Mgc) and the dark matter halo mass (Mhalo) of a galaxy has been posited as a consequence of a causal relation between the formation of dark matte…
We study the present-day rotational velocity ($V_{rot}$) and velocity dispersion ($σ$) profiles of the globular cluster (GC) systems in a sample of 50 lenticular (S0) galaxies from the E-MOSAICS galaxy formation simulations. We find that 82% of the galaxies have GCs that are rotating along the photometric major axis of the galaxy ($aligned$), while the remaining 18% of the galaxies do not ($misaligned$). This is generally consistent with the observations from the SLUGGS survey. For the $aligned$ galaxies, classified as $peaked$ $and$ $outwardly$ $decreasing$ (49%), $flat$ (24%) and $increasing…
We present a detailed comparison of the Milky Way (MW) globular cluster (GC) kinematics with the 25 Milky Way-mass cosmological simulations from the E-MOSAICS project. While the MW falls within the kinematic distribution of GCs spanned by the simulations, the relative kinematics of its metal-rich ($[\rm{Fe/H}]>-1.2$) versus metal-poor ($[\rm{Fe/H}]<-1.2$), and inner ($r<8\rm{kpc}$) versus outer ($r>8\rm{kpc}$) populations are atypical for its mass. To understand the origins of these features, we perform a comprehensive statistical analysis of the simulations, and find 18 correlations describin…
The ages and metallicities of globular clusters (GCs) are known to be powerful tracers of the properties of their progenitor galaxies, enabling their use in determining the merger histories of galaxies. However, while useful in separating GCs into individual accretion events, the orbits of GC groups themselves have received less attention as probes of their progenitor galaxy properties. In this work, we use simulations of galaxies and their GC systems from the E-MOSAICS project to explore how the present-day orbital properties of GCs are related to the properties of their progenitor galaxies. …
It has long been argued that the radial distribution of globular clusters (GCs) in the Fornax dwarf galaxy requires its dark matter halo to have a core of size $\sim 1$ kpc. We revisit this argument by investigating analogues of Fornax formed in E-MOSAICS, a cosmological hydrodynamical simulation that self-consistently follows the formation and evolution of GCs in the EAGLE galaxy formation model. In EAGLE, Fornax-mass haloes are cuspy and well described by the Navarro-Frenk-White profile. We post-process the E-MOSAICS to account for GC orbital decay by dynamical friction, which is not include…
Dynamical models allow us to connect the motion of a set of tracers to the underlying gravitational potential, and thus to the total (luminous and dark) matter distribution. They are particularly useful for understanding the mass and spatial distribution of dark matter (DM) in a galaxy. Globular clusters (GCs) are an ideal tracer population in dynamical models, since they are bright and can be found far out into the halo of galaxies. We aim to test how well Jeans-Anisotropic-MGE (JAM) models using GCs (positions and line-of-sight velocities) as tracers can constrain the mass and radial distrib…
Binary stars as dynamical tracers in globular clusters .II. Evolution of the radial distribution of the binary star fraction
Indiana University(印第安纳大学);INAF – Astrophysics and Space Science Observatory of 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);University of Bologna(博洛尼亚大学);European Southern Observatory(欧洲南方天文台)
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)
The difference in metallicity distribution functions of halo stars and globular clusters as a function of galaxy type: A tracer of globular cluster formation and evolution
Globular clusters (GCs) are often used to estimate the dark matter content of galaxies, especially dwarfs, where other kinematic tracers are lacking. These estimates typically assume spherical symmetry and dynamical equilibrium, assumptions that may not hold for the sparse GC population of dwarfs in galaxy clusters. We use a catalog of GCs tagged onto the Illustris simulation to study the accuracy of GC-based mass estimates. We focus on galaxies in the stellar mass range 10$^{8} - 10^{11.8}$ M$_{\odot}$ identified in $9$ simulated Virgo-like clusters. Our results indicate that mass estimates a…
This paper presents the chemical abundance analysis of 217 stars in the metal-poor globular cluster NGC 6752, distributed from the turn-off to the lower red giant branch. Aluminium and Lithium abundances were derived through spectral synthesis applied to spectra collected with FLAMES, both in GIRAFFE and UVES modes. The work aims to gain insight into the nature of the polluter(s) responsible for the abundance variations and C-N, Na-O, Al-Mg anti-correlations associated with the multiple population phenomenon. We found a plateau at A(Li)=2.33$\pm$0.06 dex in unevolved stars, with the average Li…
Binary Stars as Dynamical Tracers in Globular Clusters .I. First Observations of Bimodal Spatial Distributions
University of Bologna(博洛尼亚大学);INAF – Astrophysics and Space Science Observatory of Bologna(意大利国家天体物理研究所波洛尼亚天文与空间科学观测站);Indiana University(印第安纳大学);European Southern Observatory(欧洲南方天文台)
Ultra-diffuse galaxies that contain a large sample of globular clusters (GCs) offer an opportunity to test the predictions of galactic dynamics theory. NGC5846-UDG1 is an excellent example, with a high-quality sample of dozens of GC candidates. We show that the observed distribution of GCs in NGC5846-UDG1 is suggestive of mass segregation induced by gravitational dynamical friction. We present simple analytic calculations, backed by a series of numerical simulations, that naturally explain the observed present-day pattern of GC masses and radial positions. Subject to some assumptions on the GC…
On the correlation between globular clusters and the distribution of dark matter in galaxy clusters: the case of Abell 2744
Canadian Institute for Theoretical Astrophysics (CITA), University of Toronto(多伦多大学理论天体物理研究所 (CITA));Department of Physics & Astronomy, McMaster University(麦克马斯特大学物理与天文系);Instituto Galego de Física de Altas Enerxías, Universidade de Santiago de Compostela(圣地亚哥-德孔波斯特拉大学加利西亚高能物理研究所);Department of Statistical Sciences, University of Toronto(多伦多大学统计科学系);David A. Dunlap Department of Astronomy & Astrophysics, University of Toronto(多伦多大学大卫·A·邓普克天文与天体物理学系);Dunlap Institute for Astronomy & Astrophysics, University of Toronto(多伦多大学邓普克天文与天体物理研究所);Data Sciences Institute, University of Toronto(多伦多大学数据科学研究院)
The mass function of globular cluster (GC) populations is a fundamental observable that encodes the physical conditions under which these massive stellar clusters formed and evolved. The high-mass end of star cluster mass functions are commonly described using a Schechter function, with an exponential truncation mass $M_{c,*}$. For the GC mass functions in the Virgo galaxy cluster, this truncation mass increases with galaxy mass ($M_{*}$). In this paper we fit Schechter mass functions to the GCs in the most massive galaxy group ($M_{\mathrm{200}} = 5.14 \times 10^{13} M_{\odot}$) in the E-MOSA…
Star clusters as tracers of galactic nuclei properties
我们提出了一系列的$N$体模拟代表的星系核和它的恒星内容的演变,在一个接近一对一的表示。这套模拟的目的是揭示核团(NC),超大质量黑洞(SMBH)和它们所包含的星系核之间的相互作用。我们模拟的星系质量从几倍$10^8$到$10^{11}$ M $_\odot$,在它们的核中有一些球状星团,在某些情况下,还有一个中央SMBH。
The ongoing interaction between the Milky Way (MW) and its largest satellite - the Large Magellanic Cloud (LMC) - creates a significant perturbation in the distribution and kinematics of distant halo stars, globular clusters and satellite galaxies, and leads to biases in MW mass estimates from these tracer populations. We present a method for compensating these perturbations for any choice of MW potential by computing the past trajectory of LMC and MW and then integrating the orbits of tracer objects back in time until the influence of the LMC is negligible, at which point the equilibrium appr…
Multiple stellar populations (MPs) representing star-to-star light-element abundance variations are common in nearly all ancient Galactic globular clusters. Here we provide the strongest evidence yet that the populous, ~ 1.7 Gyr-old Large Magellanic Cloud cluster NGC 2173 also exhibits light-element abundance variations. Thus, our results suggest that NGC 2173 is the youngest cluster for which MPs have been confirmed to date. Our conclusion is based on the distinct bifurcation at the tip of its red-giant branch in high-quality color--magnitude diagrams generated from Hubble Space Telescope ima…
We explore how diffuse stellar light and globular clusters (GCs) can be used to trace the matter distribution of their host halo using an observational methodology. For this, we use 117 simulated dark matter (DM) haloes from the $(34.4~\rm cMpc)^3$ periodic volume of the E-MOSAICS project. For each halo, we compare the stellar surface brightness and GC projected number density maps to the surface densities of DM and total mass. We find that the dominant structures identified in the stellar light and in the GCs correspond closely with those from the DM and total mass. Our method is unaffected b…