Aggressively-Dissipative Dark Dwarfs: The Effects of Atomic Dark Matter on the Inner Densities of Isolated Dwarf Galaxies
We present the first suite of cosmological hydrodynamical zoom-in simulations of isolated dwarf galaxies for a dark sector that consists of Cold Dark Matter and a strongly-dissipative sub-component. The simulations are implemented in GIZMO and include standard baryons following the FIRE-2 galaxy for...
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Main Authors | , , , , , , |
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Format | Journal Article |
Language | English |
Published |
27.08.2024
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Subjects | |
Online Access | Get full text |
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Summary: | We present the first suite of cosmological hydrodynamical zoom-in simulations
of isolated dwarf galaxies for a dark sector that consists of Cold Dark Matter
and a strongly-dissipative sub-component. The simulations are implemented in
GIZMO and include standard baryons following the FIRE-2 galaxy formation
physics model. The dissipative dark matter is modeled as Atomic Dark Matter
(aDM), which forms a dark hydrogen gas that cools in direct analogy to the
Standard Model. Our suite includes seven different simulations of $\sim 10^{10}
M_{\odot}$ systems that vary over the aDM microphysics and the dwarf's
evolutionary history. We identify a region of aDM parameter space where the
cooling rate is aggressive and the resulting halo density profile is universal.
In this regime, the aDM gas cools rapidly at high redshifts and only a small
fraction survives in the form of a central dark gas disk; the majority
collapses centrally into collisionless dark "clumps", which are clusters of
sub-resolution dark compact objects. These dark clumps rapidly equilibrate in
the inner galaxy, resulting in an approximately isothermal distribution that
can be modeled with a simple fitting function. Even when only a small fraction
($\sim 5\%$) of the total dark matter is strongly dissipative, the central
densities of classical dwarf galaxies can be enhanced by over an order of
magnitude, providing a sharp prediction for observations. |
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DOI: | 10.48550/arxiv.2408.15317 |