The existence of quasars at redshift z > 5 indicates that supermassive black holes were present since the very early times. If they grew by accretion, the seeds of mass >~10⁵ M_Sun must have formed at z ~ 9. These seed black holes may result from the collapse and dissipation of primordial gas during the early stages of galaxy formation. I discuss the effects of the magnetic field on the collapse and fragmentation of cold clouds of gas embedded into a hot phase and a virialized dark matter halo. The field of 10^-4 G ejected by supernova remnants can halt cloud break-up at 10⁴ M_Sun. The magnetized clouds collapse into black holes, which later merge via dynamical friction into a single central object with M_bh ~ 6^.10⁶ M_Sun.

Page design by Alexander Potekhin (palex.astro@mail.ioffe.ru).
Page created on March 26, 2001.