AUSTIN, Texas — The most massive black hole in
the universe tips the cosmic scales at 18 billion times more massive than the
sun, astronomers suggest today at a meeting of the American Astronomical
Society.
Even though
researchers suggested black holes
up to this mass might exist in quasars, this is the first direct confirmation
of such a behemoth.
The hefty
gravity well is six times more massive than the previous record and is orbited
by a smaller
black hole, which allowed the measurement of the giant's mass.
Black holes
can't be seen, but astronomers detect them by noting how other objects are affected
by the tremendous gravity created in tremendously small sphere of space.
The binary
black hole system powers a quasar known as OJ287, which is located 3.5 billion
light-years from us in the constellation Cancer. The quasar — an overwhelming
beacon of light associated with a developing galaxy — has been studied in
greater detail than most quasars.
Quasars are
thought to be powered by gas falling into giant black holes boasting millions
or billions of solar masses. Though smaller than the solar system, a
quasar can outshine an entire galaxy.
This
particular quasar has a regularly pulsing light signal with two major pulses
every 12 years. The first two pulses were observed in the year 1994-1995, and
the first one of the next set in 2005. The observations helped astronomers
refine their computer models, predicting the next pulse would come on Sept. 13,
2007.
Mauri
Valtonen of the Tuorla Observatory in Finland, who presented the study, says
there is a simple physical explanation for the 12-year pulsing. "In
addition to the primary back hole in the
[accretion] disk, we have a secondary black hole that crosses the disk
twice during the orbital period," Valtonen said. "And that's what
gives us the two pulses."
An
international network of astronomers operating telescopes across the globe took
part in monitoring the quasar in September and October. The largest telescopes
involved were the German Calar Alto telescope and the Nordic optical telescope.
Sure
enough, right on schedule OJ287 sent out a light pulse on that date. No other
pulses of that kind showed up during September or October, indicating, the
astronomers say, the binary black-hole model was correct.
The next
pulse is due in January 2016.
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