Death By Black Hole In Small Galaxy?

By  //  August 27, 2014

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data provided by Chandra X-ray Observatory

ABOVE VIDEO: A star that wanders too close to a supermassive black hole is doomed, as it should be ripped apart by extreme tidal forces. The debris from the star is expected to fall towards the black hole, getting hotter and producing intense X-rays. The X-rays should then fade as the hot gas spirals inward. Using Chandra, this behavior may have been spotted, for the first time, in a dwarf galaxy. Bright X-rays from the location of this small galaxy were seen in 1999 until they faded and eventually disappeared in 2005. In the past few years, Chandra and other astronomical satellites have identified several suspected cases of a supermassive black hole ripping apart a nearby star. This newly discovered episode is different because it has been associated with a much smaller galaxy than these other cases. The black hole responsible for the destruction may be only a few hundred thousand times as massive as the Sun, making it ten times less massive than the galaxy’s supermassive black hole. Astronomers believe that black holes of this size may be the “seeds” that ultimately formed the supermassive black holes in the centers of galaxies like the Milky Way.

NASA.gov — A bright, long duration flare may be the first recorded event of a black hole destroying a star in a dwarf galaxy and the evidence comes from two independent studies using data from NASA’s Chandra X-ray Observatory and other telescopes.

As part of an ongoing search of Chandra's archival data for events signaling the disruption of stars by massive black holes, astronomers found a prime candidate. Beginning in 1999, an unusually bright X-ray source had appeared in a dwarf galaxy and then faded until it was no longer detected after 2005. (NASA.gov image)

As part of an ongoing search of Chandra’s archival data for events signaling the disruption of stars by massive black holes, astronomers found a prime candidate. Beginning in 1999, an unusually bright X-ray source had appeared in a dwarf galaxy and then faded until it was no longer detected after 2005. (NASA.gov image)

As part of an ongoing search of Chandra’s archival data for events signaling the disruption of stars by massive black holes, astronomers found a prime candidate. Beginning in 1999, an unusually bright X-ray source had appeared in a dwarf galaxy and then faded until it was no longer detected after 2005.

“We can’t see the star being torn apart by the black hole,” Peter Maksym of the University of Alabama in Tuscaloosa, Ala., who led one of the studies, “but we can track what happens to the star’s remains, and compare it with other, similar events. This one fits the profile of ‘death by a black hole.’”

A dwarf galaxy is located in the galaxy cluster Abell 1795. (NASA.gov)

A dwarf galaxy is located in the galaxy cluster Abell 1795. (NASA.gov)

Scientists predict that a star that wanders too close to a giant, or supermassive, black hole could be ripped apart by extreme tidal forces.  As the stellar debris falls toward the black hole, it would produce intense X-radiation as it is heated to millions of degrees. The X-rays would diminish in a characteristic manner as the hot gas spiraled inward.

In the past few years, Chandra and other astronomical satellites have identified several suspected cases of a supermassive black hole ripping apart a nearby star. This newly discovered episode of cosmic, black-hole-induced violence is different because it has been associated with a much smaller galaxy than these other cases.

GALAXY CLUSTER LOCATED 800 MILLION LIGHT YEARS AWAY

The so-called dwarf galaxy is located in the galaxy cluster Abell 1795, about 800 million light years from Earth. It contains about 700 million stars, far less than a typical galaxy like the Milky Way, which has between 200 and 400 billion stars.

Peter Maksym

Peter Maksym

Moreover, the black hole in this dwarf galaxy may be only be a few hundred thousand times as massive as the sun, making it ten times less massive than the galaxy’s supermassive black hole, and placing it in what astronomers call an “intermediate mass black hole” category.

“Scientists have been searching for these intermediate mass black holes for decades,” said Davide Donato of NASA’s Goddard Space Flight Center (GSFC) in Greenbelt, Md., who led a separate team of researchers. “We have lots of evidence for small black holes and very big ones, but these medium-sized ones have been tough to pin down.”


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