A Tour of Mrk 1216

Narrator (April Hobart, CXC): About a decade ago, astronomers discovered a population of small, but massive galaxies called "red nuggets." A new study using NASA's Chandra X-ray Observatory indicates that black holes have squelched star formation in these galaxies and may have used some of the untapped stellar fuel to grow to unusually massive proportions.

Red nuggets were first discovered by the Hubble Space Telescope at great distances from Earth, corresponding to times only about three or four billion years after the Big Bang. They are relics of the first massive galaxies that formed within only one billion years after the Big Bang. Astronomers think they are the ancestors of the giant elliptical galaxies seen in the local Universe. The masses of red nuggets are similar to those of giant elliptical galaxies, but they are only about a fifth of their size.

While most red nuggets merged with other galaxies over billions of years, a small number managed to slip through the long history of the cosmos untouched. These unscathed red nuggets represent a golden opportunity to study how the galaxies, and the supermassive black hole at their centers, act over billions of years of isolation.

For the first time, Chandra has been used to study the hot gas in two of these isolated red nuggets, Mrk 1216, and PGC 032673. They are located only 295 million and 344 million light years from Earth respectively, rather than billions of light years for the first known red nuggets. This X-ray emitting hot gas contains the imprint of activity generated by the supermassive black holes in each of the two galaxies.

The Chandra results show these supermassive black holes not only prevent new stars from forming, they might also swipe some of the stellar material to add bulk to themselves. This may have allowed the black holes in these two galaxies to swell to more five billion times the Sun. The Chandra data are helping to tell the story of what happens to these red nugget galaxies over their long, solitary journey through cosmic time.