Friday, October 8, 2010

Old Black Holes and New People

I think I learned something new about the Universe this week. Of course, it may all just be wrong because all science in done in fits and starts. There's this common view among non-practitioners that Science progresses linearly. The next Newton climbs up on the shoulders of old Galikeplernicus, sees over the horizon, and then walks along a geodesic right into a new wonderful paradigm. Nope. Nothing even close. A number of times we fall off trying to climb up the shoulders of the scientific Ozymandias; frequently the false paths that lead to fake horizons; a number of times we get stuck in the bogs that litter the fields of Science. It's a slow painful slog, to say the least.

But I digress. What, pray, did I learn about the Universe this week? I learned that far in the distant past, galaxies which were busy growing big black holes in their centers were not the same as the ones we see today in the Universe around us. Today, these galaxies with black holes are big and round things, and some process, probably the merging of two big galaxies, made them what they are. Things like M87, which sits in the center of the Virgo cluster.

This is M87, one of the largest galaxies in our immediate vicinity. It looks pretty boring as galaxies go. No lovely spiral arms, no brilliant young stars and limpid clouds of luminescent hydrogen gas. But you see that strange comet like thing pointing to the center of the galaxy. That's no comet. It's a stream of very, very diffuse plasma streaming out of the center, so fast that it stays in a thin stream for a 100,000 light years. The jet, as we like to call it, is shot out by the massive magnetic field of a black hole at the center of the galaxy, with a mass more than a billion times that of our own Sun. That's a thousand, million, million times the mass of our own Earth! Oh they're out there all right. I'm trying to figure out how they became the way they are.

For a black hole like this to grow, you need a lot of gas. It's hard for a lot of gas to fall into black holes today (in the Local Volume, as we like to say - that's everything out to a 100 million light years or so). Too much is locked up in stars or too hot to get close enough to the center of a galaxy. That stuff must have fallen in back when the Universe was much younger and there was a lot of gas to spare. That's where what I do comes in. I'm looking at a small number of very old galaxies that have black holes back when the Universe was 2.6 billion years old (it's now 13.7 billion years old). And the cool thing I see is that these early galaxies are not big round things like we see today. Instead, as far as I can tell, they are forming lots of stars and seem to have a whole bunch of gas. This is exactly what is needed to grow these distant black holes, so maybe this is another useful piece in this puzzle that we astronomers are putting back together. The picture on the puzzle is telling us how the gargantuan black holes we find around us today first came about. It's exciting and, boy, I need to work hard to get it out soon!

Or maybe it's all just wrong. The future will tell (if peer review doesn't get me first).

Another person who is doing similar stuff is Angela, who I met for the first time today. I know of her work, but didn't know that she is a very entertaining and interesting person. I was hanging about, wasting time in Benjamin's office, when I heard someone come up behind me and say, "You're big!" Now, this is a fact I am well aware of, but it's not something a total stranger would say as a means of introduction. Which immediately suggested to me that this person was interesting. After moving out of her way - yes, that person was Angela - she remarked that she was merely stating fact, and that she had made the long journey across the building to talk to Sri, whose office this also was. Sri was not around, so the three of us instead retired for a bit of coffee and some fun discussion about Ikea, Alexis, nightmares and alarm clocks. Very pleasant, I tell you. That intimated to me that she was entertaining. Both very good things. So is Benjamin, btw. It's nice to meet good new people.

Incidentally, I don't believe I ever mentioned the number of excellent coffee machines all around the premises. Euro 0.30 will get you a steaming groƟ Tasse which is a perfect pick-up whenever I want to stop thinking of big black holes, for fear of getting stuck in one those bogs. Certainly, I make frequent use of this resource. Also, I need to get an alarm clock.....

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