An Over-Massive Black Hole in a Typical Star-Forming Galaxy, 2 Billion Years After the Big Bang

摘要

Supermassive black holes (SMBHs) and their host galaxies are generallythought to coevolve, so that the SMBH achieves up to about 0.2 to 0.5% of thehost galaxy mass in the present day. The radiation emitted from the growingSMBH is expected to affect star formation throughout the host galaxy. Therelevance of this scenario at early cosmic epochs is not yet established. Wepresent spectroscopic observations of a galaxy at redshift z = 3.328, whichhosts an actively accreting, extremely massive BH, in its final stages ofgrowth. The SMBH mass is roughly one-tenth the mass of the entire host galaxy,suggesting that it has grown much more efficiently than the host, contrary tomodels of synchronized coevolution. The host galaxy is forming stars at anintense rate, despite the presence of a SMBH-driven gas outflow.