Black hole seen building its own galaxy

Black holes may be ‘building’ their own host galaxy, according to astronomers at the European Southern Observatory (ESO).

“The ‘chicken and egg’ question of whether a galaxy or its black hole comes first is one of the most debated subjects in astrophysics today,” says lead author David Elbaz. “Our study suggests that supermassive black holes can trigger the formation of stars, thus ‘building’ their own host galaxies. This link could also explain why galaxies hosting larger black holes have more stars.”

The team of astronomers conducted extensive observations of a peculiar object, the nearby quasar HE0450-2958, which is the only one for which a host galaxy has not yet been detected. HE0450-2958 is located some five billion light-years away.

The observations disproved the theory that the quasar’s host galaxy was hidden behind large amounts of dust. Instead, the researchers discovered that an apparently unrelated galaxy in the quasar’s immediate neighbourhood was producing stars at a rate of 350 per year – one hundred times more than rates for typical galaxies in the local Universe.

Earlier observations had shown that the companion galaxy is, in fact, under fire: the quasar is spewing a jet of highly energetic particles towards its companion, accompanied by a stream of fast-moving gas. The injection of matter and energy into the galaxy indicates that the quasar itself might be inducing the formation of stars and thereby creating its own host galaxy.

The research appears in Astronomy & Astrophysics.