James Webb Space Telescope Feed Post

Harvard ADS: Baryon-induced collapse of dark matter cores into supermassive black holes

Paper abstract: Non-linear structure formation for fermionic dark matter particles leads to dark matter density profiles with a degenerate compact core surrounded by a diluted halo. For a given fermion mass, the core has a critical mass that collapses into a supermassive black hole (SMBH). Galactic dynamics constraints suggest a ~ 100 keV/c^2 fermion, which leads to ~ 10^7 M_\odot critical core mass. Here, we show that baryonic (ordinary) matter accretion drives an initially stable dark matter core to SMBH formation and determine the accreted mass threshold that induces it. Baryonic gas density \rho_b and velocity v_b inferred from cosmological hydro-simulations and observations produce sub-Eddington accretion rates triggering the baryon-induced collapse in less than a Gyr. This process produces active galactic nuclei in galaxy mergers and the high-redshift Universe. For TXS 2116-077, merging with a nearby galaxy, the observed 3\times 10^7 M_\odot SMBH, for Q_b = \rho_b/v_b^3 = 0.125 M_\odot/(100 \text{km/s pc})^3, forms in ~ 0.6 Gyr, consistent with the 0.5-2 Gyr merger timescale and younger jet. For the farthest central SMBH detected by the \textit{Chandra} X-ray satellite in the z=10.3 UHZ1 galaxy observed by the James Webb Space Telescope (\textit{JWST}), the mechanism leads to a 4\times 10^7 M_\odot SMBH in 87-187 Myr, starting the accretion at z=12-15. The baryon-induced collapse can also explain the ~ 10^7-10^8 M_\odot SMBHs revealed by the JWST at z~ 4-6. After its formation, the SMBH can grow to a few 10^9 M_\odot in timescales shorter than a Gyr via sub-Eddington baryonic mass accretion.