ABSTRACT We present a suite of FIRE-2 cosmological zoom-in simulations of isolated field dwarf galaxies, all with masses of $M_{\rm halo} \approx 10^{10}\, {\rm M}_{\odot }$ 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. Dwarfs with smaller stellar half-mass radii (r1/2 < 500 pc) have lower σ⋆/Vmax ratios, reinforcing the idea that smaller dwarfs may reside in haloes that are more massive than is naively expected. The majority of dwarfs simulated with self-interactions 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 ΛCDM. The V1/2–r1/2 relation across all simulations is generally consistent with observations of Local Field dwarfs, though compact objects such as Tucana provide a unique challenge. Overall, the inclusion of baryons substantially reduces any distinct signatures of dark matter physics in the observable properties of dwarf galaxies. Spatially resolved rotation curves in the central regions (<400 pc) of small dwarfsmore »
The central densities of Milky Way-mass galaxies in cold and self-interacting dark matter models
ABSTRACT We present a suite of baryonic cosmological zoom-in simulations of self-interacting dark matter (SIDM) haloes within the ‘Feedback In Realistic Environment’ (FIRE) project. The three simulated haloes have virial masses of $\sim 10^{12}\, \text{M}_\odot$ at z = 0, and we study velocity-independent self-interaction cross sections of 1 and 10 ${\rm cm^2 \, g^{-1}}$. We study star formation rates and the shape of dark matter density profiles of the parent haloes in both cold dark matter (CDM) and SIDM models. Galaxies formed in the SIDM haloes have higher star formation rates at z ≤ 1, resulting in more massive galaxies compared to the CDM simulations. While both CDM and SIDM simulations show diverse shape of the dark matter density profiles, the SIDM haloes can reach higher and more steep central densities within few kpcs compared to the CDM haloes. We identify a correlation between the build-up of the stars within the half-mass radii of the galaxies and the growth in the central dark matter densities. The thermalization process in the SIDM haloes is enhanced in the presence of a dense stellar component. Hence, SIDM haloes with highly concentrated baryonic profiles are predicted to have higher central dark matter densities than more »
- Publication Date:
- NSF-PAR ID:
- 10288902
- Journal Name:
- Monthly Notices of the Royal Astronomical Society
- Volume:
- 507
- Issue:
- 1
- Page Range or eLocation-ID:
- 720 to 729
- ISSN:
- 0035-8711
- Sponsoring Org:
- National Science Foundation
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ABSTRACT Self-interacting dark matter (SIDM) models offer one way to reconcile inconsistencies between observations and predictions from collisionless cold dark matter (CDM) models on dwarf-galaxy scales. In order to incorporate the effects of both baryonic and SIDM interactions, we study a suite of cosmological-baryonic simulations of Milky-Way (MW)-mass galaxies from the Feedback in Realistic Environments (FIRE-2) project where we vary the SIDM self-interaction cross-section σ/m. We compare the shape of the main dark matter (DM) halo at redshift z = 0 predicted by SIDM simulations (at σ/m = 0.1, 1, and 10 cm2 g−1) with CDM simulations using the same initial conditions. In the presence of baryonic feedback effects, we find that SIDM models do not produce the large differences in the inner structure of MW-mass galaxies predicted by SIDM-only models. However, we do find that the radius where the shape of the total mass distribution begins to differ from that of the stellar mass distribution is dependent on σ/m. This transition could potentially be used to set limits on the SIDM cross-section in the MW.
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Accepted Manuscript1.0
- Publisher's Version of Record
- https://doi.org/10.1093/mnras/stab2173
