The Dark Matter Distributions in Low-mass Disk Galaxies. II. The Inner Density Profiles

Relatores, Nicole C.; Newman, Andrew B.; Simon, Joshua D.; Ellis, Richard S.; Truong, Phuongmai; Blitz, Leo; Bolatto, Alberto D.; Martin, Christopher; Matuszewski, Matt; Morrissey, Patrick; Neill, James D.

doi:10.3847/1538-4357/ab5305

Cited by 34 publications

(25 citation statements)

References 105 publications

(138 reference statements)

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“…HI kinematics, stellar kinematics, and photometry each give a different answer (van der Marel & Kallivayalil 2014)). Dwarf galaxies are often irregularly shaped, and also often exhibit cored density profiles (Moore 1994;Relatores et al 2019). This is the case in our simulated galaxies as well, as shown in Figure 6.…”

Section: Remaining Off-centersupporting

confidence: 77%

The Origins of Off-Centre Massive Black Holes in Dwarf Galaxies

Bellovary,

Hayoune,

Chafla

et al. 2021

Preprint

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Massive black holes often exist within dwarf galaxies, and both simulations and observations have shown that a substantial fraction of these may be off-center with respect to their hosts. We trace the evolution of off-center massive black holes (MBHs) in dwarf galaxies using cosmological hydrodynamical simulations, and show that the reason for off-center locations is mainly due to galaxy-galaxy mergers. We calculate dynamical timescales and show that off-center MBHs are unlikely to sink to their galaxys' centers within a Hubble time, due to the shape of the hosts' potential wells and low stellar densities. These wandering MBHs are unlikely to be detected electromagnetically, nor is there a measurable dynamical effect on the galaxy's stellar population. We conclude that off-center MBHs may be common in dwarfs, especially if the mass of the MBH is small or the stellar mass of the host galaxy is large. However detecting them is extremely challenging, because their accretion luminosities are very low and they do not measurably alter the dynamics of their host galaxies.

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Section: Remaining Off-centersupporting

confidence: 77%

The Origins of Off-Centre Massive Black Holes in Dwarf Galaxies

Bellovary,

Hayoune,

Chafla

et al. 2021

Preprint

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“…6 extends the analysis to the full ensemble, showing the median ratios of subhalo mass (m with disc /m no disk ), maximum circular velocity (m with disc /m nodisk ), subhalo concentration (c 2,with disc /c 2,no disc ), and logarithmic inner density slope (s 38,with disc /s 38,no disc ), as functions of the minimum host-centric distance measured in the simulations with disc, r min , of massive surviving satellites in all of the 100 realizations. Here, for the density slope we follow the convention in observational studies to measure it at fixed physical aperture (as opposed to a relative aperture of 0.01l vir that is convenient for theoretical studies) -in particular, we use the average slope between l = 0.3 kpc and 0.8 kpc, s 38 ≡ − ln[ρ(0.8 kpc)/ρ(0.3 kpc)]/ln(0.8/0.3), following Relatores et al (2019). On average, the disc decreases the subhalo mass by up to 60%, v max by 20%, concentration by 5%, and steepens the density slope by 8%.…”

Section: Effect Of the Disc Potentialmentioning

confidence: 99%

SatGen: a semi-analytical satellite galaxy generator – I. The model and its application to Local-Group satellite statistics

Jiang

Dekel

Freundlich

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present a semi-analytical model of satellite galaxies, SatGen, which can generate large statistical samples of satellite populations for a host halo of desired mass, redshift, and assembly history. The model combines dark matter (DM) halo merger trees, empirical relations for the galaxy–halo connection, and analytical prescriptions for tidal effects, dynamical friction, and ram-pressure stripping. SatGen emulates cosmological zoom-in hydrosimulations in certain aspects. Satellites can reside in cored or cuspy DM subhaloes, depending on the halo response to baryonic physics that can be formulated from hydrosimulations and physical modelling. The subhalo profile and the stellar mass and size of a satellite evolve depending on its tidal mass-loss and initial structure. The host galaxy can include a baryonic disc and a stellar bulge, each described by a density profile that allows analytic satellite orbit integration. SatGen complements simulations by propagating the effect of halo response found in simulated field galaxies to satellites (not properly resolved in simulations) and outperforms simulations by sampling the halo-to-halo variance of satellite statistics and overcoming artificial disruption due to insufficient resolution. As a first application, we use the model to study satellites of Milky Way (MW)- and M31-sized hosts, making it emulate simulations of bursty star formation and of smooth star formation, respectively, and to experiment with a disc potential in the host halo. We find that our model reproduces the observed satellite statistics reasonably well. Different physical recipes make a difference in satellite abundance and spatial distribution at the 25 per cent level, not large enough to be distinguished by current observations given the halo-to-halo variance. The MW/M31 disc depletes satellites by ${\sim } 20{{\ \rm per\ cent}}$ and has a subtle effect of diversifying the internal structure of satellites, which is important for alleviating certain small-scale problems. We discuss the conditions for a massive satellite to survive in MW/M31.

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“…with α ∼ −1 (Dubinski & Carlberg 1991;Navarro, Frenk & White 1997;Navarro et al 2004), while observations of some dark matter dominated galaxies appear to suggest profiles are better described by constant density cores at small radii, i.e. α ∼ 0 (Flores & Primack 1994;Moore 1994;Salucci & Burkert 2000;Swaters et al 2003;Gentile et al 2004;Spekkens, Giovanelli & Haynes 2005;Walter et al 2008;Oh et al 2011;Relatores et al 2019). Another potentially related discrepancy is called the Too Big to Fail problem (Boylan-Kolchin, Bullock & Kaplinghat 2011): Milky Way satellite galaxies are observed to have much smaller inner dark matter densities compared to the surplus of subhaloes predicted from [dark matter only (DMO)] cosmological N-body simulations.…”

mentioning

confidence: 99%

A dark matter profile to model diverse feedback-induced core sizes of ΛCDM haloes

Lazar

Bullock

Boylan-Kolchin

et al. 2020

Monthly Notices of the Royal Astronomical Society

133

129

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We analyze the cold dark matter density profiles of 54 galaxy halos simulated with FIRE-2 galaxy formation physics, each resolved within $0.5\%$ of the halo virial radius. These halos contain galaxies with masses that range from ultra-faint dwarfs (M⋆ ≃ 104.5M⊙) to the largest spirals (M⋆ ≃ 1011M⊙) and have density profiles that are both cored and cuspy. We characterize our results using a new, analytic density profile that extends the standard two-parameter Einasto form to allow for a pronounced constant-density core in the resolved innermost radius. With one additional core-radius parameter, rc, this three-parameter core-Einasto profile is able to characterize our feedback-impacted dark matter halos more accurately than other three-parameter profiles proposed in the literature. In order to enable comparisons with observations, we provide fitting functions for rc and other profile parameters as a function of both M⋆ and M⋆/Mhalo. In agreement with past studies, we find that dark matter core formation is most efficient at the characteristic stellar-mass to halo-mass ratio M⋆/Mhalo ≃ 5 × 10−3, or M⋆ ∼ 109 M⊙, with cores that are roughly the size of the galaxy half-light radius, rc ≃ 1 − 5 kpc. Furthermore, we find no evidence for core formation at radii $\gtrsim 100\ \rm pc$ in galaxies with M⋆/Mhalo < 5 × 10−4 or M⋆ ≲ 106 M⊙. For Milky Way-size galaxies, baryonic contraction often makes halos significantly more concentrated and dense at the stellar half-light radius than DMO runs. However, even at the Milky Way scale, FIRE-2 galaxy formation still produces small dark matter cores of ≃ 0.5 − 2 kpc in size. Recent evidence for a ∼2 kpc core in the Milky Way’s dark matter halo is consistent with this expectation.

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The Dark Matter Distributions in Low-mass Disk Galaxies. II. The Inner Density Profiles

Cited by 34 publications

References 105 publications

The Origins of Off-Centre Massive Black Holes in Dwarf Galaxies

The Origins of Off-Centre Massive Black Holes in Dwarf Galaxies

SatGen: a semi-analytical satellite galaxy generator – I. The model and its application to Local-Group satellite statistics

A dark matter profile to model diverse feedback-induced core sizes of ΛCDM haloes

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