Tiny Galaxy Big Black Hole

This appears to be a highlydisturbed galaxy and it is surely interesting and confirms that our knowledgeis terribly limited.

This one should be kept underobservation somehow because it is likely to be a source of events on thegalactic scale that we can actually see.

Otherwise it is a great image.

A tiny galaxy that hides a big secret

http://blogs.discovermagazine.com/badastronomy/2011/01/11/a-tiny-galaxy-that-hides-a-big-secret/

Astronomers have just announced something that took me bysurprise: the dwarf irregular galaxy named Henize 2-10 has a fairly beefysupermassive black hole in it! Here’s a picture of the galaxy:

[Click to unendwarfenate.]

The image is a composite of images from Hubble (red, green, and blue),radio images from the Very Large Array in New Mexico (yellow), and X-rays from theChandra Observatory (purple). The cross marks the location of the black hole.

Henize 2-10 is pretty dinky, only about 3000 light years across — theMilky Way is 100,000 for comparison. It’s about 30 million light years away,which is kinda sorta close by, at least close enough to get a decent look atit. Now, we know that big galaxies like ours have these monster black holes intheir very centers; the Milky Way’s is about 4 million times the mass of theSun. Many galaxies have much larger ones, like Andromeda which harbors one 35times as massive as ours.

Some smaller galaxies have supermassive black holes as well, but in generalthese dwarf galaxies have some structure to them, with a well-defined core.Henize 2-10, as you can see, it a mess! It doesn’t have much overall structure,which is why it’s classified as an irregular galaxy. The thinking for biggalaxies is that the black hole forms at the same time as the galaxy itself,and to regulate the growth of each other. When you look at lots of biggalaxies, there’s a pretty clear overall correlation between the mass of theblack hole and the galaxy around it.

So it’s pretty weird that Henize 2-10 has a supermassive black hole atall, but it turns out the hole is also about a million times the mass of theSun — that’s pretty freakin’ big for such a tiny galaxy! That’s 1/4 the mass ofour own black hole, in a galaxy that itself is far smaller than ours.

As I wrote earlier today, black holes can focus and expeltremendous beams of matter and energy which blast away from the hole. In thiscase, these beams have slammed into material hundreds of light years away, welloutside the core of Henize 2-10, lighting this gas up at different wavelengths.You can see that as the yellow (radio) blobs to the left and right of the blackhole’s location in the big picture at the top, or as the pink areas in this smallerinset image of the galaxy (which just shows the Hubble image only). The brightregion around the black hole is also bright in X-rays, a dead giveaway that theblack hole is actively feeding.

So why does this goofy galaxy have a dragon at its heart? The Milky Wayas two companion galaxies, called the Magellanic Clouds, which are roughly thesame size as Henize 2-10, but neither hosts a black hole like this one. Whatmakes Henize special?

That’s a good question, and one for which we don’t have a good answeryet. But finding special cases like this help astronomers constrain theirideas; any models they have for black hole formation and growth now have toaccount for this tiny, amorphous galaxy that doesn’t seem to care that it’sbreaking the mold.