Dwarf Galaxies in CDM, WDM, and SIDM: Disentangling Baryons and Dark Matter Physics. (arXiv:1811.11791v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Fitts_A/0/1/0/all/0/1">Alex Fitts</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Boylan_Kolchin_M/0/1/0/all/0/1">Michael Boylan-Kolchin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bozek_B/0/1/0/all/0/1">Brandon Bozek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bullock_J/0/1/0/all/0/1">James S. Bullock</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Graus_A/0/1/0/all/0/1">Andrew Graus</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Robles_V/0/1/0/all/0/1">Victor Robles</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hopkins_P/0/1/0/all/0/1">Philip F. Hopkins</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+El_Badry_K/0/1/0/all/0/1">Kareem El-Badry</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Garrison_Kimmel_S/0/1/0/all/0/1">Shea Garrison-Kimmel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Faucher_Giguere_C/0/1/0/all/0/1">Claude-André Faucher-Giguère</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wetzel_A/0/1/0/all/0/1">Andrew Wetzel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Keres_D/0/1/0/all/0/1">Dušan Kereš</a>
We present a suite of FIRE-2 cosmological zoom-in simulations of isolated
field dwarf galaxies, all with masses of $M_mathrm{halo} approx
10^{10},$M$_odot$ at $z=0$, across a range of dark matter models. For the
first time, we compare how both self-interacting dark matter (SIDM) and/or warm
dark matter (WDM) models affect the assembly histories as well as the central
density structure in fully hydrodynamical simulations of dwarfs. Overall, the
inclusion of self-interactions does little to affect the mass assembly of these
halos (both dark matter and baryonic), while WDM models generally delay dark
matter halo formation and reduce galaxies’ stellar masses at $z=0$. Dwarfs with
smaller stellar half-mass radii (r$_{1/2}<500$ pc) have lower
$sigma_star/V_mathrm{max}$ ratios, reinforcing the idea that smaller dwarfs
may reside in halos that are more massive than is naively expected.
Surprisingly, the majority of dwarfs simulated with self-interactions
(regardless of the warmth of the dark matter) actually experience contraction
of their inner density profiles with the addition of baryons relative to the
cores produced in dark-matter-only runs, though the simulated dwarfs are always
less centrally dense than in $Lambda$CDM. Our V$_{1/2}-$r$_{1/2}$ relation is
overall consistent with observations of Local Field dwarfs, though compact
objects such as Tucana provide a unique challenge. Spatially-resolved rotation
curves in the central regions ($<400$ pc) of small dwarfs could provide a way
to distinguish between CDM, WDM, and SIDM: at the masses probed in this
simulation suite, cored density profiles in dwarfs with small r$_{1/2}$ values
can only originate from dark matter self-interactions.
We present a suite of FIRE-2 cosmological zoom-in simulations of isolated
field dwarf galaxies, all with masses of $M_mathrm{halo} approx
10^{10},$M$_odot$ at $z=0$, across a range of dark matter models. For the
first time, we compare how both self-interacting dark matter (SIDM) and/or warm
dark matter (WDM) models affect the assembly histories as well as the central
density structure in fully hydrodynamical simulations of dwarfs. Overall, the
inclusion of self-interactions does little to affect the mass assembly of these
halos (both dark matter and baryonic), while WDM models generally delay dark
matter halo formation and reduce galaxies’ stellar masses at $z=0$. Dwarfs with
smaller stellar half-mass radii (r$_{1/2}<500$ pc) have lower
$sigma_star/V_mathrm{max}$ ratios, reinforcing the idea that smaller dwarfs
may reside in halos that are more massive than is naively expected.
Surprisingly, the majority of dwarfs simulated with self-interactions
(regardless of the warmth of the dark matter) actually experience contraction
of their inner density profiles with the addition of baryons relative to the
cores produced in dark-matter-only runs, though the simulated dwarfs are always
less centrally dense than in $Lambda$CDM. Our V$_{1/2}-$r$_{1/2}$ relation is
overall consistent with observations of Local Field dwarfs, though compact
objects such as Tucana provide a unique challenge. Spatially-resolved rotation
curves in the central regions ($<400$ pc) of small dwarfs could provide a way
to distinguish between CDM, WDM, and SIDM: at the masses probed in this
simulation suite, cored density profiles in dwarfs with small r$_{1/2}$ values
can only originate from dark matter self-interactions.
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