Kavli Affiliate: Lina Necib
| First 5 Authors: Maria C. Straight, Michael Boylan-Kolchin, James S. Bullock, Philip F. Hopkins, Xuejian Shen
| Summary:
We investigate the central density structure of dark matter halos in cold
dark matter (CDM) and self-interacting dark matter (SIDM) models using
simulations that are part of the Feedback In Realistic Environments (FIRE)
project. For simulated halos of dwarf galaxy scale ($M_{rm halo}(z=0)approx
10^{10},M_odot$), we study the central structure in both dissipationless
simulations and simulations with full FIRE-2 galaxy formation physics. As has
been demonstrated extensively in recent years, both baryonic feedback and
self-interactions can convert central cusps into cores, with the former process
doing so in a manner that depends sensitively on stellar mass at fixed $M_{rm
halo}$. Whether the two processes (baryonic feedback and self-interactions) are
distinguishable, however, remains an open question. Here we demonstrate that,
compared to feedback-induced cores, SIDM-induced cores transition more quickly
from the central region of constant density to the falling density at larger
radial scales. This result holds true even when including identical galaxy
formation modeling in SIDM simulations as is used in CDM simulations, since
self-interactions dominate over galaxy formation physics in establishing the
central structure of SIDM halos in this mass regime. The change in density
profile slope as a function of radius therefore holds the potential to
discriminate between self-interactions and galaxy formation physics as the
driver of core formation in dwarf galaxies.
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