The Host Galaxy of a Dormant, Overmassive Black Hole at z = 6.7 may be Restarting Star Formation

Abstract

JWST is discovering a large population of z > 4 supermassive black holes (SMBHs) that are overmassive with respect to the stellar content of their hosts. A previous study developed a physical model to interpret this overmassive population as the result of quasar feedback acting on a compact host galaxy. In this Note, we apply this model to JADES GN 1146115, a dormant SMBH at z = 6.7 whose mass is ∼40% of the host’s mass in stars and accreting at ∼2% of the Eddington limit. The host has been forming stars at the low rate of ∼1 M ⊙ yr−1 for the past ∼100 Myr. Our model suggests that this galactic system is on the verge of a resurgence of global star formation activity. This transition comes after a period of domination by the effect of its overmassive black hole, whose duration is comparable to typical quasar lifetimes.