Astronomers have captured a strange phenomenon never seen before: distant dwarf galaxies preparing to merge, accompanied by a giant black hole at their center. What’s more: Not just one, but two pairs were discovered!
Two new candidates for “active galactic binary nuclei” have been found by a team of researchers, according to a study accepted and published in The Astrophysical Journal ArXiv was pre-released. The phenomenon has been theorized for a long time, but has so far hardly been observed. More specifically, it is a merger of supermassive black holes located at the centers of galaxies. And not just any dwarf galaxies with fewer than a billion stars. For comparison: the Milky Way contains 200 to 400 billion stars!
And this type of merger is particularly interesting because the very first galaxies, which were nowhere near the size of the Milky Way, were dwarf galaxies. They then merged into the galaxies we know today. Most dwarf galaxies and black holes in the early Universe are likely to have grown much larger now through repeated mergers,” said Brenna Wells, co-author of the study, in one press release. “In a way, dwarf galaxies are our galactic ancestors, evolving over billions of years to give rise to large galaxies, like our own Milky Way.”
© Nasa, CXC, University of Alabama, M. Micic et al.
– The two pairs of dwarf galaxies about to collide.
Captured using black hole accretion disks.
The two pairs of galaxies, named Mirabilis and Elstir & Vinteuil, are 760 million light-years and 3.2 billion light-years away from us, respectively, and were imaged using NASA’s Chandra X-ray Observatory. They were discovered through the accretion disk of their central black holes: matter falling into the black hole heats up to millions of degrees and forms a disk of plasma around the star that emits a large amount of X-rays.
The first pair, Mirabilis, are in the final stages of merging and display a long tail caused by the tidal effects of the collision. In contrast, Elstir & Vinteuil is still in its infancy and is gradually forming a bridge of stars and gas connecting the two galaxies. “Follow-up observations of these two systems will allow us to study processes critical to understanding galaxies and their early-stage black holes,” concluded Jimmy Irwin, co-author of the study.
Editor: Futura, written by Léa Fournasson.
Cover Photo: ©Maryna Olyak, Adobe Stock -The two pairs of galaxies observed by the researchers tell us about the first-ever galaxy collisions.
2.Figure:© Nasa, CXC, University of Alabama, M. Micic et al.