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Scientists zero in on black hole

NASA / ESA / STScI / OSU / SRON

is image of Markarian 509 was taken in April 2007 with the Hubble Space Telescope's Wide Field Camera 2. Observations reveal bullets of gas being driven away from the galaxy's supermassive black hole, and a corona of hot gas hovering above the disk of in-falling matter.

Astronomers have taken an unprecedented look at the tumult surrounding a supermassive black hole, using a quintet of space telescopes. And they're finding out that it's a horribly messy eater.

The black hole in question is at the center of the galaxy Markarian 509, which is nearly 500 million light-years away. Unlike the black hole at the center of our own Milky Way galaxy, Markarian 509's colossal black hole is sucking huge amounts of dust and gas into its gravitational maw. Its mass is 300 million times that of the sun, or roughly 75 times the mass of the Milky Way's central black hole.


Five space telescopes focused on Markarian 509: the European Space Agency's XMM-Newton telescope and Integral gamma-ray observatory, NASA's Chandra X-Ray Observatory and Swift gamma-ray probe, and the Hubble Space Telescope. The ground-based William Herschel Telescope and PARITEL telescope were also put on the case.

The telescopes couldn't see the black hole itself, but they could see the strong emissions of radiation in various wavelengths from the wreckage that's swirling around it. The X-ray observatories — XMM-Newton and Chandra — were particularly useful.

Markarian 509's gravitational monster is known for its variability. During the 100-day observing campaign, its brightness in the soft X-ray band jumped up by 60 percent, signaling a cosmic feeding frenzy. In a news release, the European Space Agency said giant, blobby bullets of gas were stripped away from the whirlpool and ejected at speeds of millions of miles per hour.

The astronomers were surprised to find that the bullets were coming from a dusty reservoir of matter waiting to fall into the black hole, situated more than 15 light-years away. That's farther away than some astronomers thought was possible.

"There has been a debate in astronomy for some time about the origin of the outflowing gas," said Jelle Kaastra of the SRON Netherlands Institute for Space Research. Kaastra coordinated the international black-hole research team of 26 astronomers from 21 institutes.

M. Weiss / CXC / NASA

In this artist's illustration, turbulent winds of gas swirl around a black hole. Some of the gas is spiraling inward toward the black hole, but another part is blown away.

The dusty reservoir forms a doughnut-shaped torus around the black hole. Material spirals in toward the black hole, creating a whirling accretion disk. The disk appears to give rise to a "corona" that hovers above it.

"This corona absorbs and reprocesses the ultraviolet light from the disk, energizing it and converting it into X-ray light," Kaastra said in a SRON news release. "It must have a temperature of a few million degrees. ... This discovery allows us to make sense of some of the observations of active galaxies that have been hard to explain so far."

The researchers said the corona appears to be the source of the X-rays and gamma rays that drive the bullets outward.

The initial results are being published as a series of seven papers in the journal Astronomy and Astrophysics, titled "Multiwavelength Campaign on Mrk 509." SRON said still more results are in preparation.

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