Observations with the Gemini North telescope in Hawai’i reveal evidence for what astronomers are calling the largest black holes ever measured in our nearby cosmological neighborhood. This result is crucial in explaining the long-standing mystery of where the largest black holes are hiding in our present-day universe.
The two black holes discovered in this research are more than two thousand times bigger than the one that resides at the center of our galaxy, which has a mass of about 4 million times that of our sun. Tod R. Lauer, a member of the team of astronomers who made the discovery, noted that the event horizons (the region inside of which light can no longer escape) of these black holes are far larger than our solar system. Each is five to ten times bigger than Pluto’s orbit.
Supermassive black holes appear to have existed when the universe was extremely young. Evidence for this comes from quasars — extremely bright objects thought to have played host to very massive black holes in the early universe.
University of California at Berkeley graduate student Nicholas McConnell is first author of a paper on the black holes in the December 8, 2011, issue of the journal Nature. He said:
They couldn’t just go away. So where are these black holes hiding now?
The discovery of these two supermassive black holes, each approaching 10 billion times the mass of the Sun, is providing answers to this question.
McConnell and his advisor and team-leader Chung-Pei Ma were joined by researchers from the universities of Texas, Michigan, the Dunlap Institute for Astronomy and Astrophysics at the University of Toronto, Canada, as well as the National Optical Astronomy Observatory (NOAO) in Arizona. Ma said:
The boisterous quasars that we see when we look back in time at the young universe may have passed through a turbulent youth to become the quiescent giant elliptical galaxies we see today. The black holes at the centers of these galaxies are no longer fed by accreting gas and have become dormant and hidden. We see them only because of their gravitational pull on nearby orbiting stars.
The question remains whether there is a limit as to how big a black hole can get. Ma said:
Larger black holes tend to live in bigger parent galaxies so is it nature or nurture that determines how large a black hole can grow?
Bottom line: A team of astronomers using the Gemini North telescope in Hawai’i have discovered evidence for two black holes that they say are the largest ever measured in our nearby cosmological neighborhood. This result is crucial in explaining the long-standing mystery of where the largest black holes are hiding in our present-day universe.