Big Black Holes In Dwarf Galaxies

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For the first time, NASA Chandra X-ray telescope has been used to discover a pair of black holes in dwarf galaxies that are on a collision course. The Chandra team explains.  Credit: NASA/CXC/A. Hobart

Transcript

00:00Visit Chandra's Beautiful Universe

00:04Dwarf Galaxies

00:08Astronomers have discovered the first evidence

00:12for giant black holes in dwarf galaxies on a collision course.

00:16This result from NASA's Chandra X-ray Observatory has important

00:20ramifications for understanding how the first wave of black holes in galaxies

00:24grew in the early universe. Collisions between the pairs

00:28of dwarf galaxies have pulled gas toward the giant black holes they each

00:32contain, causing the black holes to grow. Eventually

00:36the likely collision of the black holes will cause them to merge into

00:40much larger black holes. The pairs of galaxies will also

00:44merge into one. Scientists think the

00:48universe was awash with small galaxies known as dwarf galaxies

00:52several hundred million years after the Big Bang. Most

00:56merged with others in the crowded smaller

00:58volume of the early universe

01:00setting in motion the building of larger and

01:02larger galaxies now seen

01:04around the local universe.

01:06Dwarf galaxies

01:08by definition contain stars

01:10with a total mass less than about

01:123 billion times that of the Sun

01:14compared to a total mass

01:16of about 60 billion suns estimated

01:18for the Milky Way.

01:20The earliest dwarf galaxies are impossible to observe

01:24with current technology because they are extraordinarily faint at their large distances.

01:30Astronomers have been able to observe

01:32two in the process of merging at much closer distances to Earth

01:36but without signs of black holes in both galaxies.

01:40Astronomers have found many examples of black holes on collision courses

01:44in large galaxies that are relatively close by.

01:46But searches for them in dwarf galaxies are much more challenging

01:50and until now had failed.

01:52The new study overcame these challenges by implementing

01:56a systematic survey of deep Chandra X-ray observations

02:00and comparing them with infrared data

02:02from NASA's Wide Infrared Survey Explorer

02:04or WISE Telescope

02:06and optical data from the Canada-France-Hawaii Telescope.

02:10Using this technique,

02:12a group of researchers identified

02:14two pairs of merging dwarf galaxies

02:16in separate galaxy clusters.

02:18The first

02:20is ABEL 133

02:22which is located about

02:24760 million light-years away.

02:26The second

02:28is the galaxy cluster ABEL 1758S

02:30which is about

02:323.2 billion light-years from Earth.

02:34Astronomers will use these systems as analogues

02:38for ones in the early Universe

02:40so they can drill down into questions

02:42about the first galaxies,

02:44their black holes,

02:46and star formation the collisions caused

02:48many billions of years ago.

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