Self-Interacting Dark Matter Halos and the Gravothermal Catastrophe

By S. Balberg, Stuart L. Shapiro, S. Inagaki. 2001

185 citations recorded by the source corpus.

We study the evolution of an isolated spherical halo of self-interacting dark matter (SIDM) in the gravothermal fluid formalism. We show that the thermal relaxation time tr of an SIDM halo with the central density and velocity dispersion of a typical dwarf galaxy is significantly shorter than its age. We find a self-similar solution for the evolution of an SIDM halo in the limit where the mean free path between collisions, λ, is longer than the gravitational scale height H everywhere. Typical halos formed in this long mean free path regime relax to a quasi-stationary gravothermal density profile characterized by a nearly homogeneous core and a power-law halo where ρ ∝ r-2.19. We solve the more general time-dependent problem and show that the contracting core evolves to sufficiently high density that λ inevitably becomes smaller than H in the innermost region. The core undergoes secular collapse to a singular state (the "gravothermal catastrophe") in a time tcoll ≈ 290tr, which is longer than the Hubble time for a typical dark matter-dominated galaxy core at the present epoch. Our model calculations are consistent with previous more detailed N-body simulations for SIDM, providing a simple physical interpretation of their results and extending them to higher spatial resolution and longer evolution times. At late times, mass loss from the contracting dense inner core to the ambient halo is significantly moderated, so that the final mass of the inner core may be appreciable when it becomes relativistic and radially unstable to dynamical collapse to a black hole.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/b3dd3403a29621119bde68786d54b59baadacbfb

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Citations in the corpus

Core formation in dwarf haloes with self-interacting dark matter: no fine-tuning necessary (2014, background): “Older simulations of isolated halos showed core recollapse after a few dynamical times for an equivalent cross section larger than ∼ 5 cm2 g−1 (scaled appropriately to the mass of Pippin; Kochanek & White, 2000; Balberg et al., 2002; Koda & Shapiro, 2011).”
Cosmological Simulations with Self-Interacting Dark Matter I: Constant Density Cores and Substructure (2012, background): “The centers of SIDM halos are expected to have constant density isothermal cores that arise as kinetic energy is transmitted from the hot outer halo inward (Balberg et al. 2002; Colı́n et al. 2002; Ahn & Shapiro 2005; Koda & Shapiro 2011).”