NGC 4649, Arp 116
In the constellation Virgo
4.5 billion times the mass of the Sun
Diameter 45 billion miles (27 billion km), roughly eight times the diameter of Neptune's orbit around the Sun
The center of the giant elliptical galaxy Messier 60 is relatively quiet and peaceful. In this calm environment, gas is falling inward from all directions at a steady pace. Astronomers have used this infalling gas to estimate the mass of the black hole in the galaxy's core.
In 2003, Texas astronomer Karl Gebhardt estimated the mass at about 2 billion times by the mass of the Sun by measuring the motions of stars near the center of the galaxy. The stars are accelerated by the black hole's powerful gravity, so motions of their orbits reveals the black hole's mass.
In 2008, Gebhardt was a member of a team that used Chandra X-Ray Observatory to test a new technique for measuring a black hole's mass. Led by Philip Humphrey of the University of California-Irvine, the team found that the temperature of the gas in M60 climbed steadily as the gas grew closer to the center.
The black hole's gravity pulls the gas inward, squeezing it together and thereby making it hotter. From the temperature profile -- the change in temperature at different distances from the center -- the team could deduce the mass of the black hole; as the mass increases, the gas grows more compressed, so it gets hotter.
Their measurements yielded a black hole mass of about 3.4 billion times the mass of the Sun, making it one of the heaviest black holes yet confirmed.
The Chandra observations, combined with those of optical and radio telescopes, indicate that the center of M60 is calm. The accretion disk around the supermassive black hole is fairly quiet, so it is not producing any big outbursts of energy. And, unlike the black holes in many other galaxies, this one is not beaming out strong "jets" of charged particles.
A New Way to Weigh Giant Black Holes (Chandra X-Ray Observatory)
How do you weigh the biggest black holes in the universe? One answer now comes from a completely new and independent technique that astronomers have developed using data from NASA's Chandra X-ray Observatory.
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This document was last modified: March 14, 2012.