Black holes located in dwarf galaxies usually stop star formation, but now one has been seen seeding new stars through a huge plume of ionised gas
19 January 2022
A black hole at the centre of a dwarf galaxy has birthed new stars by expelling jets of gas hundreds of light years long.
Astronomers have observed supermassive black holes creating star-forming regions before, but until now it was thought that black holes residing in dwarf galaxies, which contain a billion stars or less, hindered star formation.
Zachary Schutte at Montana State University and his colleagues observed the black hole in a dwarf galaxy called Hen 2-10 spewing a plume of ionised gas nearly 500 light years long, stretching from the galactic centre to a cloud of gas on the galaxy’s edge where stars were forming.
Schutte and his team used the Hubble Space Telescope to observe and carry out spectroscopy on the dim dwarf galaxy, which is about 34 million light years away in the constellation Pyxis.
Astronomers are interested in dwarf galaxies like Hen 2-10 because they could be similar to the galaxies found in the very early universe. If the laws governing galaxy evolution haven’t changed, understanding how these galaxies form stars could tell us how galaxies like our own Milky Way might have first evolved.
“Any time that we find new interactions between [black holes] and their host galaxies, especially in dwarf galaxies like this, it speaks to possible ways stars were formed and how galaxies grew in the early universe,” says Schutte.
Dwarf galaxies typically have a black hole or supernova at their centre, but they are so dim that it can be difficult to tell which they contain. But the high-resolution method that Schutte and his team used for Hen 2-10 resulted in strong evidence of a black hole, providing a potential road map for imaging other dwarf galaxies.
“It’s a real breakthrough because it allows us to say with confidence that it is a [black hole] source as opposed to a supernova,” says Joanna Piotrowska at the University of Cambridge. “That is a major step in this puzzle.”
Journal reference: Nature, DOI: 10.1038/s41586-021-04215-6
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