Fluffy Galaxy with Surprise Center

The American Astronomical Society meeting in Seattle is in full swing, so the astronomy news is going to be flying this week! One of the first press releases is one I’ve been looking forward to for weeks. Several UVa and NRAO astronomers discovered a supermassive black hole in a dwarf galaxy!

I actually heard about this discovery over lunch one day with my fellow grad students. Amy Reines, a Ph.D. candidate in our department, was working on the press release for this awesome new discovery. She was looking at a dwarf galaxy, Henize 2-10, which is about the same mass as one of the Milky Way’s nearby dwarf galaxies, the Large Magellanic Cloud. Her research is on super star clusters, or massive, prolific star forming regions. In studying the active star forming regions in this galaxy, she came across something odd. Using the Very Large Array, she found an interesting radio source that did not look like a super star cluster.

Hubble image of this very distant dwarf in blue/white, with the radio emission in pink.

She and several colleagues followed up this weird discovery with observations from the Chandra X-Ray Observatory. This showed a bright, compact source where the radio source was. This evidence, along with the jet-like features in the radio image suggested one thing… a supermassive black hole.

Hubble in red, green, and blue, VLA in yellow, Chandra in purple, and a red cross marking the black hole.

Supermassive black holes are found in pretty much every galaxy with a bulge. They can be millions or billions of times the mass of the sun. Most are “quiet,” but many are active, lighting up their surroundings as the matter falling into them rapidly spins around the black hole. Some of these are even spewing out jets of material seen in radio images, such as with this galaxy. Since supermassive black holes are so ubiquitous, it has been questioned, which comes first? The black hole or the galaxy bulge?

This black hole is weird in that it resides in a dwarf galaxy that has no stellar bulge! I mean, just look at that fluffy thing. This may be a clue that way in the universe’s past, galaxies had black holes before the stellar bulges formed around them.

So, the real reason we were discussing this at lunch was to come up with a good analogy for the strange finding. Indeed, it was serendipitous, in that Amy and her colleagues did not go looking for this black hole, but when they saw something odd, they diligently followed up and made a fascinating discovery. We were likening it to all kinds of things, like finding treasure in your backyard, or dinosaur bone in your sock draw. Actually, I think my favorite was, it’s like going to a Star Trek convention and meeting David Tennant. Or something like that.

Whatever analogy you’d like to make, this is certainly a great finding and will add to the debate of which came first, the bulge or the black hole. (And, congrats, Amy!)

Preprint of the Nature paper by Reines, Sivakoff, Johnson, and Brogan, and image credit also to Nidever. All cool CVille astronomers, by the way!

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