Image of the Day: Twin Gigantic Black Holes Found at Galaxy Center


A galaxy already known to have one enormous  black hole at its core is actually home to two of these scary giants. Astronomers discovered the second monster black hole at the center of the galaxy Markarian 739, which is about 425 million light-years from Earth in observations by NASA's Swift satellite and the Chandra X-Ray Observatory.

The two black holes are separated by about 11,000 light years, which is about one-third the distance between our solar system and the center of the Milky Way. One light-year is about 6 trillion miles.

Both black holes are intensely active and classified as "supermassive," each a mass equivalent to millions — or even billions — of stars like our sun.  It's rare to find one active monster black hole, let alone two, in the same galaxy, researchers said.

"At the hearts of most large galaxies, including our own Milky Way, lies a supermassive black hole weighing millions of times the sun's mass," said the study's lead author Michael Koss,  a researcher at NASA's Goddard Space Flight Center and the University of Maryland in College Park, in a statement. "Some of them radiate billions of times as much energy as the sun."

Astronomers suspect that the active binary supermassive black hole structure can occur when galaxies collide.

"If two galaxies collide and each possesses a supermassive black hole, there should be times when both black holes switch on as AGN," said study co-author Richard Mushotzky, also of the University of Maryland in College Park.

The astronomers discovered the dual black hole heart of Markarian 739 by using NASA's Swift satellite's Burst Alert Telescope, which maps intense sources of X-ray emissions in the sky, to seek out potential active galactic nuclei. Researchers can then zoom in on potential candidates with the Chandra X-Ray Observatory.

Markarian 739's second black hole was invisible in the ultraviolet, visible and radio ranges of the light spectrum, so it remained hidden until this new study, researchers said.

The two giant black holes at the center of Markarian 739, which is also known by the name NGC 3758, are not the first monster black hole twins seen by astronomers, and they're not the closest either.  Both records are held by the galaxy NGC 6240, a galaxy that is about 330 million light-years from Earth.

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