Supermassive black holes from collapsing dark matter Bose–Einstein condensates

Abstract

The discovery of active galactic nuclei at redshifts 6 suggests that supermassive black holes (SMBHs) formed early on. Growth of the remnants of population III stars by accretion of matter, both baryonic as well as collisionless dark matter (DM), leading up to formation of SMBHs is a very slow process. Therefore, such models encounter difficulties in explaining quasars detected at . Furthermore, massive particles making up collisionless DM have not only so far eluded experimental detection but they also do not satisfactorily explain gravitational structures on small scales.In recent years, there has been a surge in research activities concerning cosmological structure formation that involve coherent, ultra-light bosons in a dark fluid-like or fuzzy cold DM state. In this paper, we study collapse of such ultra-light bosonic halo DM that is in a Bose–Einstein condensate (BEC) phase to give rise to SMBHs on dynamical time scales. Time evolution of such self-gravitating BECs is examined using the Gross–Pitaevskii equation in the framework of time-dependent variational method. Comprised of identical dark bosons of mass m, BECs can collapse to form black holes of mass Meff on time scales ∼108 yrs provided . In particular, ultra-light dark bosons of mass can lead to SMBHs with mass at . Recently observed radio-galaxies in the ELAIS-N1 deep field with aligned jets can also possibly be explained if vortices of a rotating cluster size BEC collapse to form spinning SMBHs with angular momentum , where nW and M are the winding number and mass of a vortex, respectively.