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1. Origin and evolution of ultradiffuse galaxies in different environments

   https://doi.org/10.1093/mnras/stad1053  

   Benavides, José A.; Sales, Laura V.; Abadi, Mario G.; Marinacci, Federico; Vogelsberger, Mark; Hernquist, Lars (April 2023, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We study the formation of ultradiffuse galaxies (UDGs) using the cosmological hydrodynamical simulation TNG50 of the Illustris-TNG suite. We define UDGs as dwarf galaxies in the stellar mass range $$\rm {7.5 \le log (M_{\star } / {\rm M}_{\odot }) \le 9 }$$ that are in the 5 per cent most extended tail of the simulated mass–size relation. This results in a sample of UDGs with half-mass radii $$\rm {r_{h \star } \gtrsim 2 \ kpc}$$ and surface brightness between $$\rm {24.5}$$ and $$\rm {28 \ mag \ arcsec^{-2}}$$, similar to definitions of UDGs in observations. The large cosmological volume in TNG50 allows for a comparison of UDGs properties in different environments, from the field to galaxy clusters with virial mass $$\rm {M_{200} \sim 2 \times 10^{14} ~ {\rm M}_{\odot }}$$. All UDGs in our sample have dwarf-mass haloes ($$\rm {M_{200}\sim 10^{11} ~ {\rm M}_{\odot } }$$) and show the same environmental trends as normal dwarfs: field UDGs are star-forming and blue while satellite UDGs are typically quiescent and red. The TNG50 simulation predicts UDGs that populate preferentially higher spin haloes and more massive haloes at fixed $$\rm {M_{\star }}$$ compared to non-UDG dwarfs. This applies also to most satellite UDGs, which are actually ‘born’ UDGs in the field and infall into groups and clusters without significant changes to their size. We find, however, a small subset of satellite UDGs ($$\lesssim 10~{{\ \rm per\ cent}}$$) with present-day stellar size a factor ≥1.5 larger than at infall, confirming that tidal effects, particularly in the lower mass dwarfs, are also a viable formation mechanism for some of these dwarfs, although sub-dominant in this simulation. 

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2. Extinguishing the FIRE: environmental quenching of satellite galaxies around Milky Way-mass hosts in simulations

   https://doi.org/10.1093/mnras/stac1706  

   Samuel, Jenna; Wetzel, Andrew; Santistevan, Isaiah; Tollerud, Erik; Moreno, Jorge; Boylan-Kolchin, Michael; Bailin, Jeremy; Pardasani, Bhavya (June 2022, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT The star formation and gas content of satellite galaxies around the Milky Way (MW) and Andromeda (M31) are depleted relative to more isolated galaxies in the Local Group (LG) at fixed stellar mass. We explore the environmental regulation of gas content and quenching of star formation in z = 0 galaxies at $$M_{*}=10^{5\!-\!10}\, \rm {M}_{\odot }$$ around 14 MW-mass hosts from the Feedback In Realistic Environments 2 (FIRE-2) simulations. Lower mass satellites ($$M_{*}\lesssim 10^7\, \rm {M}_{\odot }$$) are mostly quiescent and higher mass satellites ($$M_{*}\gtrsim 10^8\, \rm {M}_{\odot }$$) are mostly star forming, with intermediate-mass satellites ($$M_{*}\approx 10^{7\!-\!8}\, \rm {M}_{\odot }$$) split roughly equally between quiescent and star forming. Hosts with more gas in their circumgalactic medium have a higher quiescent fraction of massive satellites ($$M_{*}=10^{8\!-\!9}\, \rm {M}_{\odot }$$). We find no significant dependence on isolated versus paired (LG-like) host environments, and the quiescent fractions of satellites around MW-mass and Large Magellanic Cloud (LMC)-mass hosts from the FIRE-2 simulations are remarkably similar. Environmental effects that lead to quenching can also occur as pre-processing in low-mass groups prior to MW infall. Lower mass satellites typically quenched before MW infall as central galaxies or rapidly during infall into a low-mass group or a MW-mass galaxy. Most intermediate- to high-mass quiescent satellites have experienced ≥1–2 pericentre passages (≈2.5–5 Gyr) within a MW-mass halo. Most galaxies with $$M_{*}\gtrsim 10^{6.5}\, \rm {M}_{\odot }$$ did not quench before falling into a host, indicating a possible upper mass limit for isolated quenching. The simulations reproduce the average trend in the LG quiescent fraction across the full range of satellite stellar masses. Though the simulations are consistent with the Satellites Around Galactic Analogs (SAGA) survey’s quiescent fraction at $$M_{*}\gtrsim 10^8\, \rm {M}_{\odot }$$, they do not generally reproduce SAGA’s turnover at lower masses. 

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3. The progenitors of the intra-cluster light and intra-cluster globular clusters in galaxy groups and clusters

   https://doi.org/10.1093/mnras/stae848  

   Ahvazi, Niusha; Sales, Laura V; Doppel, Jessica E; Benson, Andrew; D’Souza, Richard; Rodriguez-Gomez, Vicente (March 2024, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We use the TNG50 from the IllustrisTNG suite of cosmological hydrodynamical simulation, complemented by a catalogue of tagged globular clusters, to investigate the properties and build up of two extended luminous components: the intra-cluster light (ICL) and the intra-cluster globular clusters (ICGCs). We select the 39 most massive groups and clusters in the box, spanning the range of virial masses $$5 \times 10^{12} \lt \rm M_{200}/\rm {\rm M}_{\odot } \lt 2 \times 10^{14}$$. We find good agreement between predictions from the simulations and current observational estimates of the fraction of mass in the ICL and its radial extension. The stellar mass of the ICL is only $$\sim 10~{{\ \rm per\ cent}}$$–20 per cent of the stellar mass in the central galaxy but encodes useful information on the assembly history of the group or cluster. About half the ICL in all our systems is brought in by galaxies in a narrow stellar mass range, M* = 1010–1011 M⊙. However, the contribution of low-mass galaxies (M* < 1010 M⊙) to the build up of the ICL varies broadly from system to system, $$\sim 5~{{\ \rm per\ cent}}-45~{{\ \rm per\ cent}}$$, a feature that might be recovered from the observable properties of the ICL at z = 0. At fixed virial mass, systems where the accretion of dwarf galaxies plays an important role have shallower metallicity profiles, less metal content, and a lower stellar mass in the ICL than systems where the main contributors are more massive galaxies. We show that intra-cluster GCs are also good tracers of this history, representing a valuable alternative when diffuse light is not detectable. 

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4. Dark matter haloes in the multicomponent model. III. From dwarfs to galaxy clusters

   https://doi.org/10.1093/mnras/stab3764  

   Todoroki, Keita; Medvedev, Mikhail V (January 2022, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT A possibility of DM being multicomponent has a strong implication on resolving decades-long known cosmological problems on small scale. In addition to elastic scattering, the model allows for inelastic interactions, which can be characterized by a ‘velocity kick’ parameter. The simplest 2cDM model with cross-section $$0.01\lesssim \sigma /m\lt 1\, \textrm {cm}^{2}{ \rm g}^{-1}$$ and the kick velocity $$V_{\mathrm{ k}}\simeq 100\, \rm {km\, s}^{-1}$$ have been shown to robustly resolve the missing satellites, core-cusp, and too-big-to-fail problems in N-body cosmological simulations tested on Milky Way (MW)-like haloes of a virial mass $${\sim}5 \times 10^{11}\, {\rm M_{\odot }}$$ (Papers I & II). With the aim of further constraining the parameter space available for the 2cDM model, we extend our analysis to dwarf and galaxy cluster haloes with their virial mass of ∼107−108 and $${\sim}10^{13} - 10^{14}\, {\rm M_{\odot }}$$, respectively. We find that σ0/m ≳ 0.1 cm2g−1 is preferentially disfavoured for both dwarfs and galaxy cluster haloes in comparison with observations, while σ0/m = 0.001 cm2g−1 causes little perceptible difference from that of the CDM counterpart for most of the cross-section’s velocity dependence studied in this work. Our main result is that within the reasonable set of parameters, the 2cDM model can successfully explain the observational trends seen in dwarf galaxy and galaxy cluster haloes, and the model leaves us an open window for other possible alternative DM models. 

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5. Globular clusters as tracers of the dark matter content of dwarfs in galaxy clusters

   https://doi.org/10.1093/mnras/staa3915  

   Doppel, Jessica E; Sales, Laura V; Navarro, Julio F; Abadi, Mario G; Peng, Eric W; Toloba, Elisa; Ramos-Almendares, Felipe (February 2021, Monthly Notices of the Royal Astronomical Society)

   null (Ed.)

   ABSTRACT Globular clusters (GCs) are often used to estimate the dark matter content of galaxies, especially dwarf galaxies, 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 catalogue of GCs tagged on to the Illustris simulation to study the accuracy of GC-based mass estimates. We focus on galaxies in the stellar mass range 108–1011.8 M⊙ identified in nine simulated Virgo-like clusters. Our results indicate that mass estimates are, on average, accurate in systems with GC numbers NGC ≥ 10 and where the uncertainty of individual GC line-of-sight velocities is smaller than the inferred velocity dispersion, σGC. In cases where NGC ≤ 10, however, biases may result, depending on how σGC is computed. We provide calibrations that may help alleviate these biases in methods widely used in the literature. As an application, we find a number of dwarfs with $$M_{*} \sim 10^{8.5}\, \mathrm{M}_{\odot }$$ – comparable with the ultra-diffuse galaxy NGC 1052-DF2 (DF2), notable for the low σGC of its 10 GCs – that have $$\sigma _{\rm GC} \sim 7\!-\!15\, {\rm km \,s}^{-1}$$. These DF2 analogues correspond to relatively massive systems at their infall time (M200 ∼ 1–3 × 1011 M⊙), which have retained only 3–17 GCs and have been stripped of more than 95 per cent of their dark matter. Our results suggest that extreme tidal mass loss in otherwise normal dwarf galaxies may be a possible formation channel for ultra-diffuse objects such as DF2. 

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