NASA’S powerful Chandra X-ray Observatory has discovered an ancient galaxy bursting with dark matter.
Its name is Markarian 1216. This compact elliptical galaxy is a “red nugget” type, formed about a billion years after the Big Bang. The vast amount of dark matter has caused it to float in loneliness.
Stars there are within 10% of the age of the universe. That’s almost as old as the universe itself.
Mrk 1216 lies 295 million light-years away. Researchers have found that the galaxy has gone through a different evolution process than typical galaxies. That’s both in terms of its stars and the invisible dark matter that holds the galaxy together.
While other red nugget type galaxies went on to grow and absorb other, smaller galaxies over time, this one didn’t. Mrk 1216 stopped making progress, its growth slowed down, and it’s now floating in deep space alone.
David Boute and Aaron Barth from the University of California, Irvine, used Chandra to measure the x-ray brightness and temperature of hot gas at different distances from the center of the galaxy and used the results to estimate how much dark matter was present.
“When we compared the Chandra data to our computer models, we found a much stronger concentration of dark matter was required than we find in other galaxies of similar total mass,” explains Buote.
“This tells us the history of Markarian 1216 is very different from the typical galaxy. Essentially all of its stars and dark matter was assembled long ago with little added in the past 10 billion years.”
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The study suggests the halo of dark matter formed around its core about 3-4 billion years after the big bang.
Previous estimates suggested its central supermassive black hole is more massive than expected for a galaxy of its mass. But the new study concludes the black hole weighs no more than 4 billion times the mass of the Sun.
The findings appeared in the June 1st, 2019 issue of The Astrophysical Journal.