Universal gravothermal evolution of isolated self-interacting dark matter halos for velocity-dependent cross-sections

• Published in: Monthly notices of the Royal Astronomical Society Vol. 523; no. 3; pp. 4786 - 4800
• Main Authors: Outmezguine, Nadav Joseph, Boddy, Kimberly K, Gad-Nasr, Sophia, Kaplinghat, Manoj, Sagunski, Laura
• Format: Journal Article
• Language: English
• Published: Oxford University Press 08-06-2023
• Subjects: galaxies: evolution; dark matter
• ISSN: 0035-8711; 1365-2966
• DOI: 10.1093/mnras/stad1705

ABSTRACT
We study the evolution of isolated self-interacting dark matter halos using spherically symmetric gravothermal equations allowing for the scattering cross-section to be velocity dependent. We focus our attention on the large class of models where the core is in the long mean free path regime for a substantial time. We find that the temporal evolution exhibits an approximate universality that allows velocity-dependent models to be mapped onto velocity-independent models in a well-defined way using the scattering time-scale computed when the halo achieves its minimum central density. We show how this time-scale depends on the halo parameters and an average cross-section computed at the central velocity dispersion when the central density is minimum. The predicted collapse time is fully defined by the scattering time-scale, with negligible variation due to the velocity dependence of the cross-section. We derive new self-similar solutions that provide an analytic understanding of the numerical results.