http://arxiv.org/abs/2305.05067

One necessary step for probing the nature of self-interacting dark matter (SIDM) particles with astrophysical observations is to pin down any possible velocity dependence in the SIDM cross section. Major challenges for achieving this goal include eliminating, or mitigating, the impact of the baryonic components and tidal effects within the dark matter halos of interest — the effects of these processes can be highly degenerate with those of dark matter self-interactions at small scales. In this work we select 9 isolated galaxies and brightest cluster galaxies (BCGs) with baryonic components small enough such that the baryonic gravitational potentials do not significantly influence the halo gravothermal evolution processes. We then constrain the parameters of a cross section model $\sigma(v)=\sigma_0/(1+v^2/\omega^2)^2$ with the measured rotation curves and stellar kinematics through the gravothermal fluid formalism and isothermal method. We are able to constrain a best-fit double power-law result with the gravothermal fluid formalism $\log(\sigma_0/[\mathrm{cm^2/g}])=2.6/[(\log(\omega/[\mathrm{km/s}])/1.9)^{0.85}+(\log(\omega/[\mathrm{km/s}])/1.9)^{5.5}]-1.1$ with $\log(\omega/[\mathrm{km/s}])\leq3.7$ and a scatter of 0.5 dex at a 68% confidence level. The constraint given by the isothermal model is $\log(\sigma_0/[\mathrm{cm^2/g}])=3.9/[(\log(\omega/[\mathrm{km/s}])/1.6)^{0.29}+(\log(\omega/[\mathrm{km/s}])/1.6)^{5.1}]-0.34$ with $1.4\leq\log(\omega/[\mathrm{km/s}])\leq3.5$ and a scatter of 0.34 dex at 68% confidence level. Cross sections constrained by the two methods are consistent at $2\sigma$ confidence level, but the isothermal method prefers cross sections greater than the gravothermal approach constraints by a factor of $\sim4$.

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S. Yang, F. Jiang, A. Benson, et. al.
Wed, 10 May 23
28/65

Comments: 14 pages, 10 figures