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1. Satellite mass functions and the faint end of the galaxy mass–halo mass relation in LCDM

   https://doi.org/10.1093/mnras/stac2057  

   Santos-Santos, Isabel M. E.; Sales, Laura V.; Fattahi, Azadeh; Navarro, Julio F. (July 2022, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT The abundance of the faintest galaxies provides insight into the nature of dark matter and the process of dwarf galaxy formation. In the LCDM scenario, low-mass haloes are so numerous that the efficiency of dwarf formation must decline sharply with decreasing halo mass in order to accommodate the relative scarcity of observed dwarfs and satellites in the Local Group. The nature of this decline contains important clues to the mechanisms regulating the onset of galaxy formation in the faintest systems. We explore here two possible models for the stellar mass (M*)–halo mass (M200) relation at the faint end, motivated by some of the latest LCDM cosmological hydrodynamical simulations. One model includes a sharp mass threshold below which no luminous galaxies form, as expected if galaxy formation proceeds only in systems above the hydrogen-cooling limit. In the second model, M* scales as a steep power law of M200 with no explicit cut-off, as suggested by recent semi-analytical work. Although both models predict satellite numbers around Milky Way-like galaxies consistent with current observations, they predict vastly different numbers of ultrafaint dwarfs and of satellites around isolated dwarf galaxies. Our results illustrate how the satellite mass function around dwarfs may be used to probe the M*–M200 relation at the faint end and to elucidate the mechanisms that determine which low-mass haloes ‘light up’ or remain dark in the LCDM scenario. 

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2. Photometric mass estimation and the stellar mass–halo mass relation for low mass galaxies

   https://doi.org/10.1093/mnras/stac3610  

   Zaritsky, Dennis; Behroozi, Peter (December 2022, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We present a photometric halo mass estimation technique for local galaxies that enables us to establish the stellar mass–halo mass (SMHM) relation down to stellar masses of 105 M⊙. We find no detectable differences among the SMHM relations of four local galaxy clusters or between the cluster and field relations and we find agreement with extrapolations of previous SMHM relations derived using abundance matching approaches. We fit a power law to our empirical SMHM relation and find that for adopted NFW dark matter profiles and for M* < 109 M⊙, the halo mass is Mh = 1010.35 ± 0.02(M*/108 M⊙)0.63 ± 0.02. The normalization of this relation is susceptible to systematic modelling errors that depend on the adopted dark matter potential and the quoted uncertainties refer to the uncertainties in the median relation. For galaxies with M* < 109 M⊙ that satisfy our selection criteria, the scatter about the fit in Mh, including uncertainties arising from our methodology, is 0.3 dex. Finally, we place lower luminosity Local Group galaxies on the SMHM relationship using the same technique, extending it to M* ∼ 103 M⊙ and suggest that some of these galaxies show evidence for additional mass interior to the effective radius beyond that provided by the standard dark matter profile. If this mass is in the form of a central black hole, the black hole masses are in the range of intermediate mass black holes, 10(5.7 ± 0.6) M⊙, which corresponds to masses of a few percent of Mh, well above values extrapolated from the relationships describing more massive galaxies. 

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3. The mass-loss rates of star clusters with stellar-mass black holes: implications for the globular cluster mass function

   https://doi.org/10.1093/mnras/stad1287  

   Gieles, Mark; Gnedin, Oleg Y. (May 2023, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT Stellar-mass black holes (BHs) can be retained in globular clusters (GCs) until the present. Simulations of GC evolution find that the relaxation driven mass-loss rate is elevated if BHs are present, especially near dissolution. We capture this behaviour in a parametrized mass-loss rate, bench marked by results from N-body simulations, and use it to evolve an initial GC mass function (GCMF), similar to that of young massive clusters in the Local Universe, to an age of 12 Gyr. Low-metallicity GCs ([Fe/H] ≲ −1.5) have the highest mass-loss rates, because of their relatively high BH masses, which combined with their more radial orbits and stronger tidal field in the past explains the high turnover mass of the GCMF ($$\sim 10^5\, {\rm M}_\odot$$ ) at large Galactic radii ($$\gtrsim 10\, {\rm kpc}$$ ). The turnover mass at smaller Galactic radii is similar because of the upper mass truncation of the initial GCMF and the lower mass-loss rate due to the higher metallicities. The density profile in the Galaxy of mass lost from massive GCs ($$\gtrsim 10^{5}\, {\rm M}_\odot$$ ) resembles that of nitrogen-rich stars in the halo, confirming that these stars originated from GCs. We conclude that two-body relaxation is the dominant effect in shaping the GCMF from a universal initial GCMF, because including the effect of BHs reduces the need for additional disruption mechanisms. 

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4. The Impact of Environment on Late-time Evolution of the Stellar Mass–Halo Mass Relation

   https://doi.org/10.3847/1538-4357/ab1d55  

   Golden-Marx, Jesse B.; Miller, Christopher J. (June 2019, The Astrophysical Journal)
5. Refined Mass and Geometric Measurements of the High-mass PSR J0740+6620

   https://doi.org/10.3847/2041-8213/ac03b8  

   Fonseca, E.; Cromartie, H. T.; Pennucci, T. T.; Ray, P. S.; Kirichenko, A. Yu.; Ransom, S. M.; Demorest, P. B.; Stairs, I. H.; Arzoumanian, Z.; Guillemot, L.; et al (July 2021, The Astrophysical Journal Letters)