Black hole with mass 17 billion times that of the Sun discovered
Using the Hobby-Eberly Telescope at The University of Texas at Austin's McDonald Observatory, astronomers have measured the mass of what may be the most massive black hole yet -- 17 billion Suns -- in galaxy NGC 1277.
The unusual black hole makes up 14 percent of its galaxy's mass, rather than the usual 0.1 percent.
This galaxy and several more in the same study could change theories of how black holes and galaxies form and evolve.
NGC 1277 lies 220 million light-years away in the constellation Perseus. The galaxy is only ten percent the size and mass of our own Milky Way. Despite NGC 1277's diminutive size, the black hole at its heart is more than 11 times as wide as Neptune's orbit around the Sun.
"This is a really oddball galaxy. It's almost all black hole. This could be the first object in a new class of galaxy-black hole systems," said team member Karl Gebhardt of The University of Texas at Austin.
Furthermore, the most massive black holes have been seen in giant blobby galaxies called "ellipticals," but this one is seen in a relatively small lens-shaped galaxy (in astronomical jargon, a "lenticular galaxy").
The find comes out of the Hobby-Eberly Telescope Massive Galaxy Survey (MGS). The study's endgame is to better understand how black holes and galaxies form and grow together, a process that isn't well understood.
"At the moment there are three completely different mechanisms that all claim to explain the link between black hole mass and host galaxies' properties. We do not understand yet which of these theories is best," said lead author Remco van den Bosch, who began this work while holding the W. J. McDonald postdoctoral fellowship at The University of Texas at Austin. He is now at the Max Planck Institute for Astronomy in Heidelberg, Germany.
The problem is lack of data. Astronomers know the mass of fewer than 100 black holes in galaxies. But measuring black hole masses is difficult and time-consuming. So the team developed the HET Massive Galaxy Survey to winnow down the number of galaxies that would be interesting to follow up on.
Though still ongoing, the team has studied 700 of their 800 galaxies with HET.
"This study is only possible with HET. The telescope works best when the galaxies are spread all across the sky. This is exactly what HET was designed for," Gebhardt said.
The work will be published in the journal Nature.