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1. Infall Profiles for Supercluster-scale Filaments

   https://doi.org/10.3847/1538-4357/ac815b  

   Odekon, Mary Crone; Jones, Michael G.; Graham, Lucas; Kelley-Derzon, Jessica; Halstead, Evan (August 2022, The Astrophysical Journal)

   Abstract We present theoretical expectations for infall toward supercluster-scale cosmological filaments, motivated by the Arecibo Pisces–Perseus Supercluster Survey (APPSS) to map the velocity field around the Pisces–Perseus Supercluster (PPS) filament. We use a minimum spanning tree applied to dark matter halos the size of galaxy clusters to identify 236 large filaments within the Millennium simulation. Stacking the filaments along their principal axes, we determine a well-defined, sharp-peaked velocity profile function that can be expressed in terms of the maximum infall rateV_maxand the distanceρ_maxbetween the location of maximum infall and the principal axis of the filament. This simple, two-parameter functional form is surprisingly universal across a wide range of linear mass densities.V_maxis positively correlated with the halo mass per length along the filament, andρ_maxis negatively correlated with the degree to which the halos are concentrated along the principal axis. We also assess an alternative, single-parameter method usingV₂₅, the infall rate at a distance of 25 Mpc from the axis of the filament. Filaments similar to the PPS have $V_{\max }=612\pm$116 km s⁻¹, ${\rho }_{\max }=8.9\pm 2.1$Mpc, andV₂₅= 329 ± 68 km s⁻¹. We create mock observations to model uncertainties associated with viewing angle, lack of three-dimensional velocity information, limited sample size, and distance uncertainties. Our results suggest that it would be especially useful to measure infall for a larger sample of filaments to test our predictions for the shape of the infall profile and the relationships among infall rates and filament properties. 

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2. Forecasts for Galaxy Formation and Dark Matter Constraints from Dwarf Galaxy Surveys

   https://doi.org/10.3847/1538-4357/ad3bb1  

   Nadler, Ethan_O; Gluscevic, Vera; Driskell, Trey; Wechsler, Risa_H; Moustakas, Leonidas_A; Benson, Andrew; Mao, Yao-Yuan (May 2024, The Astrophysical Journal)

   Abstract The abundance of faint dwarf galaxies is determined by the underlying population of low-mass dark matter (DM) halos and the efficiency of galaxy formation in these systems. Here, we quantify potential galaxy formation and DM constraints from future dwarf satellite galaxy surveys. We generate satellite populations using a suite of Milky Way (MW)–mass cosmological zoom-in simulations and an empirical galaxy–halo connection model, and assess sensitivity to galaxy formation and DM signals when marginalizing over galaxy–halo connection uncertainties. We find that a survey of all satellites around one MW-mass host can constrain a galaxy formation cutoff at peak virial masses of ${\mathcal{M}}_{50}={10}^8{M}_{\odot }$at the 1σlevel; however, a tail toward low ${\mathcal{M}}_{50}$prevents a 2σmeasurement. In this scenario, combining hosts with differing bright satellite abundances significantly reduces uncertainties on ${\mathcal{M}}_{50}$at the 1σlevel, but the 2σtail toward low ${\mathcal{M}}_{50}$persists. We project that observations of one (two) complete satellite populations can constrain warm DM models withm_WDM≈ 10 keV (20 keV). Subhalo mass function (SHMF) suppression can be constrained to ≈70%, 60%, and 50% that in cold dark matter (CDM) at peak virial masses of 10⁸, 10⁹, and 10¹⁰M_⊙, respectively; SHMF enhancement constraints are weaker (≈20, 4, and 2 times that in CDM, respectively) due to galaxy–halo connection degeneracies. These results motivate searches for faint dwarf galaxies beyond the MW and indicate that ongoing missions like Euclid and upcoming facilities including the Vera C. Rubin Observatory and Nancy Grace Roman Space Telescope will probe new galaxy formation and DM physics. 

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3. Substructure at High Speed. II. The Local Escape Velocity and Milky Way Mass with Gaia eDR3

   https://doi.org/10.3847/1538-4357/ac4244  

   Necib, Lina; Lin, Tongyan (February 2022, The Astrophysical Journal)

   Abstract Measuring the escape velocity of the Milky Way is critical in obtaining the mass of the Milky Way, understanding the dark matter velocity distribution, and building the dark matter density profile. In Necib & Lin, we introduced a strategy to robustly measure the escape velocity. Our approach takes into account the presence of kinematic substructures by modeling the tail of the stellar distribution with multiple components, including the stellar halo and the debris flow called the Gaia Sausage (Enceladus). In doing so, we can test the robustness of the escape velocity measurement for different definitions of the “tail” of the velocity distribution and the consistency of the data with different underlying models. In this paper, we apply this method to the Gaia eDR3 data release and find that a model with two components is preferred, although results from a single-component fit are also consistent. Based on a fit to retrograde data with two bound components to account for the relaxed halo and the Gaia Sausage, we find the escape velocity of the Milky Way at the solar position to be $v_{\mathrm{esc}}={445}_{-8}^{+25}$km s⁻¹. A fit with a single component to the same data gives $v_{\mathrm{esc}}={472}_{-12}^{+17}$km s⁻¹. Assuming a Navarro−Frenck−White dark matter profile, we find a Milky Way concentration of $c_{200}={19}_{-7}^{+11}$and a mass of $M_{200}={4.6}_{-0.8}^{+1.5}\times {10}^{11}{M}_{\odot }$, which is considerably lighter than previous measurements. 

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4. 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)

   Abstract 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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5. Stars Crushed by Black Holes. II. A Physical Model of Adiabatic Compression and Shock Formation in Tidal Disruption Events

   https://doi.org/10.3847/1538-4357/ac3fb9  

   Coughlin, Eric R.; Nixon, C. J. (February 2022, The Astrophysical Journal)

   Abstract We develop a Newtonian model of a deep tidal disruption event (TDE), for which the pericenter distance of the star,r_p, is well within the tidal radius of the black hole,r_t, i.e., whenβ≡r_t/r_p≫ 1. We find that shocks form forβ≳ 3, but they are weak (with Mach numbers ∼1) for allβ, and that they reach the center of the star prior to the time of maximum adiabatic compression forβ≳ 10. The maximum density and temperature reached during the TDE follow much shallower relations withβthan the previously predicted ${\rho }_{\max }\propto {\beta }^3$and $T_{\max }\propto {\beta }^2$scalings. Belowβ≃ 10, this shallower dependence occurs because the pressure gradient is dynamically significant before the pressure is comparable to the ram pressure of the free-falling gas, while aboveβ≃ 10, we find that shocks prematurely halt the compression and yield the scalings ${\rho }_{\max }\propto {\beta }^{1.62}$and $T_{\max }\propto {\beta }^{1.12}$. We find excellent agreement between our results and high-resolution simulations. Our results demonstrate that, in the Newtonian limit, the compression experienced by the star is completely independent of the mass of the black hole. We discuss our results in the context of existing (affine) models, polytropic versus non-polytropic stars, and general relativistic effects, which become important when the pericenter of the star nears the direct capture radius, atβ∼ 12.5 (2.7) for a solar-like star disrupted by a 10⁶M_⊙(10⁷M_⊙) supermassive black hole. 

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