00:01Visit Chandra's Beautiful Universe
00:05Dwarf Galaxies
00:10Astronomers 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 contain
00:32causing the black holes to grow. Eventually
00:36the likely collision of the black holes will cause them to merge into much larger
00:40black holes. The pairs of galaxies will also merge
00:44into one. Scientists think the universe
00:48was awash with small galaxies known as dwarf galaxies
00:52several hundred million years after the Big Bang. Most merged
00:56with others in the crowded, smaller volume
00:58of the early universe, setting
01:00in motion the building of larger and larger
01:02galaxies now seen around
01:04the local universe.
01:07Dwarf galaxies
01:08by definition contain stars
01:10with a total mass less than about
01:113 billion times that of the Sun
01:13compared to a total mass of about
01:1660 billion suns estimated
01:18for the Milky Way.
01:20The earliest dwarf galaxies are impossible
01:23to observe with current technology
01:25because they are extraordinarily faint
01:27at their large distances.
01:30Astronomers have been able to observe
01:31two in the process of merging
01:33at much closer distances to Earth
01:35but without signs of black holes
01:37in both galaxies.
01:40Astronomers have found many examples
01:42of black holes on collision courses
01:43in large galaxies that are relatively
01:46close by. But searches for them
01:48in dwarf galaxies are much more challenging
01:50and until now had failed.
01:52The new study overcame these challenges
01:55by implementing a systematic survey
01:57of deep Chandra X-ray observations
01:59and 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
02:08Hawaii telescope.
02:10Using this technique,
02:12a group of researchers identified
02:14two pairs of merging dwarf galaxies
02:16in separate galaxy clusters.
02:19The first is ABEL-133,
02:21which is located about 760 million light-years away.
02:26The second is the galaxy cluster
02:28ABEL-1758S,
02:30which is about 3.2 billion light-years from Earth.
02:36Astronomers will use these systems
02:37as analogues for ones in the early universe
02:40so they can drill down into questions
02:42about the first galaxies,
02:44their black holes,
02:45and star formation the collisions caused
02:47many billions of years ago.
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