Supermassive Black Hole Formation at High Redshifts Through a Primordial Magnetic Field

Understand

It has been proposed that primordial gas in early dark matter halos, with virial temperatures above 10^4 K, can avoid fragmentation and undergo rapid collapse, possibly resulting in a supermassive black hole (SMBH).

• This requires the gas to avoid cooling and to remain at temperatures near T=10^4 K.
• We show that this condition can be satisfied in the presence of a sufficiently strong primordial magnetic field, which heats the collapsing gas via ambipolar diffusion.
• If the field has a strength above B = 3.6 (comoving) nG, the collapsing gas is kept warm (T=10^4K) until it reaches the critical density n_crit=10^3 cm^{-3} at which the roto-vibrational states of H_2 approach local thermodynamic equilibrium.