2024ApJ...961..105D

The presence of supermassive black holes with M ∼ 10⁹M_⊙ hosted by the luminous quasars at cosmological redshift z ≥ 6 is still an open problem in astrophysical cosmology. Here we study the formation of massive black holes at high redshift (z ≫ 7) through Hoyle-Lyttleton-Bondi accretion of self-interacting dark matter (SIDM) onto a 20 M_⊙ seed black hole moving with a velocity ∼100 km s^–1 inside the short, mean-free path region of an SIDM halo. We consider observational constraints on a specific SIDM cross section, σ/m_dm = (0.1-5) cm² g^–1. Formation timescale of massive black holes with M = (10³-10⁸) M_⊙ is calculated for the universal Navarro-Frenk-White (NFW) profile, singular isothermal sphere (SIS), other power-law profiles with a cusp index 2.19 ≤ γ ≤ 2.5 of accreted dark matter, and modified-core isothermal profiles. The ambient sound speed is taken as C_s = (10-100) km s^–1. It is found that an NFW profile with halo concentration C = 4.75-32.58 estimated at z = 20 and 30 for halo masses M₂₀₀ = (10¹²-10¹⁴) M_⊙ favors formation of massive black holes with M = (10³-10⁸) M_⊙ at high redshift, well before quasar epoch. In this profile, these black holes grow within timescales (0.1-69) Myr at z = 16-20. For the SIS profile, the black hole formation timescales are short compared to NFW. For power-law profiles, massive black holes with M = (10⁶-10⁸) M_⊙ grow within a few tens to 100 Myr (z = 5-30). For modified-core isothermal profiles, the timescale of massive black hole formation is in the range (0.79-464.08) Myr (z = 8-30).