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Massive black holes found in dwarf galaxies

Date: 07 January 2020 Tags: Space

Issues

Astronomers have discovered some of the smallest galaxies known to host massive black holes. These findings may reveal how such regions of space exhibiting ultrahigh gravitational force, that even light cannot escape from are formed in the early universe.

 

Background

The study found 13 massive black holes, about 4,00,000 times as heavy as the Sun, in dwarf galaxies which are more than 100 times smaller than our own Milky Way.

 

Details

  • These galaxies are situated so far away that light from the Earth would take less than a billion years to reach them.

  • Scientists assume studying them and their galaxies will give them insights into how similar black holes in the early universe formed and then grew through galactic mergers over billions of years.

  • This event produced supermassive black holes we see in larger galaxies today, with masses of many millions or billions of times that of the Sun.

  • The scientists used the Very Large Array (VLA), a radio astronomy observatory located in central New Mexico in the U.S, to make the discovery.

  • The new VLA observations revealed that 13 of these galaxies have strong evidence for a massive black hole that is actively consuming surrounding material.

  • They also  found that, in roughly half of those 13 galaxies, the black hole is not at the center of the galaxy, unlike the case in larger galaxies.

  • Based on the findings, the astronomers suggested that the galaxies may have merged with others earlier in their history.

  • They found this inference to be consistent with computer simulations predicting that roughly half of the massive black holes in dwarf galaxies were found wandering in the outskirts of their galaxies.

Dwarf galaxies

  • A dwarf galaxy is a small galaxy composed of about 100 million up to several billion stars, a small number compared to the Milky Way's 200–400 billion stars.

  • Current theory states that most galaxies, including dwarf galaxies, form in association with dark matter, or from gas that contains metals.

  • However, NASA's Galaxy Evolution Explorer space probe identified new dwarf galaxies forming out of gases with low metallicity.

  • Because of their small size, dwarf galaxies have been observed being pulled toward and ripped by neighbouring spiral galaxies, resulting in galaxy merger.

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