Supermassive black hole formation at high redshifts through a primordial magnetic field Sethi, Shiv Haiman, Zoltán Pandey, Kanhaiya 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. H_2-cooling then remains inefficient, and the gas temperature stays near 10^4K, even as it continues to collapse to higher densities. The critical magnetic field strength required to permanently suppress H_2-cooling is somewhat higher than upper limit of approx. 2 nG from the cosmic microwave background (CMB). However, it can be realized in the rare (2-3)-sigma regions of the spatially fluctuating B-field; these regions contain a sufficient number of halos to account for the z=6 quasar BHs. American Astronomical Society 2010 info:eu-repo/semantics/article doc-type:article text http://purl.org/coar/resource_type/c_2df8fbb1 https://research-explorer.ista.ac.at/record/17639 Sethi S, Haiman Z, Pandey K. Supermassive black hole formation at high redshifts through a primordial magnetic field. <i>The Astrophysical Journal</i>. 2010;721(1):615-621. doi:<a href="https://doi.org/10.1088/0004-637x/721/1/615">10.1088/0004-637x/721/1/615</a> eng info:eu-repo/semantics/altIdentifier/doi/10.1088/0004-637x/721/1/615 info:eu-repo/semantics/altIdentifier/issn/0004-637X info:eu-repo/semantics/altIdentifier/issn/1538-4357 info:eu-repo/semantics/openAccess