Black hole measured at 50 million solar masses inside galaxy totaling at most 75 million solar masses, 700 million years after Big Bang

Astronomers have measured the mass of a supermassive black hole and its host galaxy that existed roughly 700 million years after the big bang, showing the black hole reached 50 million solar masses while the galaxy totaled at most 75 million solar masses.

The galaxy, designated Abell 2744-QSO1 or QS01, is one of hundreds of distant objects called little red dots observed by the James Webb Space Telescope. Researchers used the velocity of gas orbiting the galaxy’s center to calculate both masses, the first such measurement obtained for any black hole within a billion years of the big bang.

The black hole accounts for between 20 and 70 percent of QS01’s total mass, far above the typical fraction in present-day galaxies. Gravitational lensing by a foreground galaxy cluster magnified the light, enabling the precise velocity data. Every massive galaxy observed across the universe contains a supermassive black hole at its center.

These black holes already existed less than 500 million years after the big bang and reached hundreds of millions of solar masses by that time. Four formation channels are known: mergers of stellar-mass black holes, massive primordial seeds, direct collapse of gas clouds, and primordial black holes.

The observed mass ratio in QS01 rules out scenarios in which the galaxy assembled first and later collapsed to form its black hole.

@NewScientist reported that the data leave only direct collapse or a primordial black hole as viable explanations, both of which place the black hole ahead of the galaxy. Further observations of other little red dots will test whether QS01 represents a typical early system.