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1. ELVES. IV. The Satellite Stellar-to-halo Mass Relation Beyond the Milky Way

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

   Danieli, Shany ; Greene, Jenny E. ; Carlsten, Scott ; Jiang, Fangzhou ; Beaton, Rachael ; Goulding, Andy D. ( September 2023 , The Astrophysical Journal)

   Quantifying the connection between galaxies and their host dark matter halos has been key for testing cosmological models on various scales. BelowM_⋆∼ 10⁹M_⊙, such studies have primarily relied on the satellite galaxy population orbiting the Milky Way (MW). Here we present new constraints on the connection between satellite galaxies and their host dark matter subhalos using the largest sample of satellite galaxies in the Local Volume (D≲ 12 Mpc) to date. We use 250 confirmed and 71 candidate dwarf satellites around 27 MW-like hosts from the Exploration of Local VolumE Satellites (ELVES) Survey and use the semianalyticalSatGenmodel for predicting the population of dark matter subhalos expected in the same volume. Through a Bayesian model comparison of the observed and the forward-modeled satellite stellar mass functions (SSMFs), we infer the satellite stellar-to-halo mass relation. We find that the observed SSMF is best reproduced when subhalos at the low-mass end are populated by a relation of the form$M_{\star }\propto M_{\mathrm{peak}}^{\alpha }$, with a moderate slope of${\alpha }_{\mathrm{const}}=2.10\pm 0.01$and a low scatter, constant as a function of the peak halo mass, of${\sigma }_{\mathrm{const}}={0.06}_{-0.05}^{+0.07}$. A model with a steeper slope (α_grow= 2.39 ± 0.06) and a scatter that grows with decreasingM_peakis also consistent with the observed SSMF but is not required. Our new model for the satellite–subhalo connection, based on hundreds of Local Volume satellite galaxies, is in line with what was previously derived using only MW satellites.

    

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2. The galaxy–halo size relation of low-mass galaxies in FIRE

   https://doi.org/10.1093/mnras/stab3625  

   Rohr, Eric ; Feldmann, Robert ; Bullock, James S. ; Çatmabacak, Onur ; Boylan-Kolchin, Michael ; Faucher-Giguère, Claude-André ; Kereš, Dušan ; Liang, Lichen ; Moreno, Jorge ; Wetzel, Andrew ( December 2021 , Monthly Notices of the Royal Astronomical Society)

   Galaxy sizes correlate closely with the sizes of their parent dark matter haloes, suggesting a link between halo formation and galaxy growth. However, the precise nature of this relation and its scatter remains to be understood fully, especially for low-mass galaxies. We analyse the galaxy–halo size relation (GHSR) for low-mass ($M_\star \sim 10^{7-9}\, {\rm M}_\odot$) central galaxies over the past 12.5 billion years with the help of cosmological volume simulations (FIREbox) from the Feedback in Realistic Environments (FIRE) project. We find a nearly linear relationship between the half-stellar mass galaxy size R1/2 and the parent dark matter halo virial radius Rvir. This relation evolves only weakly since redshift z = 5: $R_{1/2}\, [{\rm kpc}] = (0.053\pm 0.002)(R_{\rm vir}/35\, {\rm kpc})^{0.934\pm 0.054}$, with a nearly constant scatter $\langle \sigma \rangle = 0.084\, [{\rm dex}]$. While this ratio is similar to what is expected from models where galaxy disc sizes are set by halo angular momentum, the low-mass galaxies in our sample are not angular momentum supported, with stellar rotational to circular velocity ratios vrot/vcirc ∼ 0.15. Introducing redshift as another parameter to the GHSR does not decrease the scatter. Furthermore, this scatter does not correlate with any of the halo properties we investigate – including spin and concentration – suggesting that baryonic processes and feedback physics are instead critical in setting the scatter in the GHSR. Given the relatively small scatter and the weak dependence of the GHSR on redshift and halo properties for these low-mass central galaxies, we propose using galaxy sizes as an independent method from stellar masses to infer halo masses.

    

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3. Forward-modelling the luminosity, distance, and size distributions of the Milky Way satellites

   https://doi.org/10.1093/mnras/stac2452  

   Manwadkar, Viraj ; Kravtsov, Andrey V. ( September 2022 , Monthly Notices of the Royal Astronomical Society)

   We use GRUMPY, a simple regulator-type model for dwarf galaxy formation and evolution, to forward model the dwarf galaxy satellite population of the Milky Way (MW) using the Caterpillar zoom-in simulation suite. We show that luminosity and distance distributions of the model satellites are consistent with the distributions measured in the DES, PS1, and SDSS surveys, even without including a model for the orphan galaxies. We also show that our model for dwarf galaxy sizes can simultaneously reproduce the observed distribution of stellar half-mass radii, r1/2, of the MW satellites and the overall r1/2–M⋆ relation exhibited by observed dwarf galaxies. The model predicts that some of the observed faint stellar systems with r1/2 < 10 pc are ultra-faint dwarf galaxies. Scaling of the stellar mass M⋆ and peak halo mass Mpeak for the model satellites is not described by a power law, but has a clear flattening of M⋆–Mpeak scaling at $M_{\rm peak}\lt 10^8\, \, M_{\odot }$ imprinted by reionization. As a result, the fraction of low mass haloes ($M_{\rm peak}\lt 10^8 \, M_{\odot }$) hosting galaxies with MV < 0 is predicted to be 50 per cent at $M_{\rm peak}\sim 3.6 \times 10^7\, \, M_{\odot }$. We find that such high fraction at that halo mass helps to reproduce the number of dwarf galaxies discovered recently in the HSC-SSP survey. Using the model we forecast that there should be the total of $440^{+201}_{-147}$ (68 per cent confidence interval) MW satellites with MV < 0 and r1/2 > 10 pc within 300 kpc and make specific predictions for the HSC-SSP, DELVE-WIDE, and LSST surveys.

    

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4. Clustering with JWST: Constraining galaxy host halo masses, satellite quenching efficiencies, and merger rates at z  = 4−10

   https://doi.org/10.1093/mnras/staa324  

   Endsley, Ryan ; Behroozi, Peter ; Stark, Daniel P ; Williams, Christina C ; Robertson, Brant E ; Rieke, Marcia ; Gottlöber, Stefan ; Yepes, Gustavo ( March 2020 , Monthly Notices of the Royal Astronomical Society)

   ABSTRACT Galaxy clustering measurements can be used to constrain many aspects of galaxy evolution, including galaxy host halo masses, satellite quenching efficiencies, and merger rates. We simulate JWST galaxy clustering measurements at z ∼ 4–10 by utilizing mock galaxy samples produced by an empirical model, the universemachine. We also adopt the survey footprints and typical depths of the planned joint NIRCam and NIRSpec Guaranteed Time Observation program planned for Cycle 1 to generate realistic JWST survey realizations and to model high-redshift galaxy selection completeness. We find that galaxy clustering will be measured with ≳5σ significance at z ∼ 4–10. Halo mass precisions resulting from Cycle 1 angular clustering measurements will be ∼0.2 dex for faint (−18 ≳ $\mathit {M}_{\mathrm{UV}}^{ }$ ≳ −19) galaxies at z ∼ 4–10 as well as ∼0.3 dex for bright ($\mathit {M}_{\mathrm{UV}}^{ }$ ∼ −20) galaxies at z ∼ 4–7. Dedicated spectroscopic follow-up over ∼150 arcmin2 would improve these precisions by ∼0.1 dex by removing chance projections and low-redshift contaminants. Future JWST observations will therefore provide the first constraints on the stellar–halo mass relation in the epoch of reionization and substantially clarify how this relation evolves at z > 4. We also find that ∼1000 individual satellites will be identifiable at z ∼ 4–8 with JWST, enabling strong tests of satellite quenching evolution beyond currently available data (z ≲ 2). Finally, we find that JWST observations can measure the evolution of galaxy major merger pair fractions at z ∼ 4–8 with ∼0.1–0.2 dex uncertainties. Such measurements would help determine the relative role of mergers to the build-up of stellar mass into the epoch of reionization. 

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5. 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)

   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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