When it comes to black holes, there are some things we know a lot about them — in general. How they form, how they affect space around them, how they eat matter.

The details, though, are maddening. We know, for example, that black holes spin — as odd as that may sound — but how they get that spin and how spin changes over time is elusive knowledge.

A new study has given us an idea of that now, though. Here’s how this works: we see that as matter falls into them, some black holes generate twin beams, called jets, which shoot away from their poles. We see this from black holes that form when stars explode, and we see them in the supermassive black holes that inhabit the centers of all big galaxies, too. We know that various physical features of the jets are tied to the rate at which the black holes spin, and this new study makes this connection more clear. The astronomers used computer models to correlate spin to the jets, and observations appear to confirm these models.

Two very interesting results came out of the study. (more…)

The Wide-field Infrared Survey Explorer was turned off a few months ago, but the science it did lives on. NASA just released a gallery of nine spiral galaxy images taken by WISE, and they’re lovely:

[Click to galactinate.]

Several of my favorite big, grand design spirals are there, like M51, M81, and M83. Note that since WISE only sees infrared light, these are false color images; the colors used are blue for 3.4 micron IR light, cyan for 4.6 microns, green for 12 microns, and red for 22 microns. The reddest light a human eye can see is very roughly 0.75 microns, to give you a comparison. In the images, star-forming regions are yellowish and/or pink, dust (in the form of long-chain organic molecules called polycyclic aromatic hydrocarbons) is green, and old stars are blue.

While looking over the images, I actually recognized the name of the one in the lower right: IC 342 (here’s a full-res WISE shot of it). This is part of a small group of galaxies near our Milky Way that is heavily obscured by dust in our galaxy. (more…)

[This is a gallery of gorgeous images, my favorites, from the orbiting infrared observatory called the Spitzer Space Telescope. Click the thumbnail picture to get a bigger picture and more information, click the big pictures to go to my original blog posts about the pictures, and scroll through the gallery using the left and right arrows.]

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I have a morality tale to tell here, but first we have to do some science. The science is part of the moral, and it’s actually rather surprising and cool. And it was reading about the science that made me chuckle, because the moral to me — as a scientist myself — was pretty obvious, but I know to others it will be as opaque as black hole.

Speaking of which…

We know that at the heart of every big galaxy lies a supermassive black hole. There’s one at the center of our galaxy — tipping the cosmic scale at 4 million times the mass of the Sun! — and one in Andromeda. In fact, looking for these monsters^* was one of the key missions for building and launching the Hubble Space Telescope, a mission it had great success with.

There be monsters here. Click to supermassivate.

Why those black holes are there, and so huge, is a matter of some discussion. We’re pretty sure they formed at the same time as their host galaxies themselves, and in fact helped the galaxies grow at the same time the galaxies fed the black holes material. We also know that big galaxies like our Milky Way grew to their current enormous size by literally colliding with and eating other galaxies. This would inevitably lead to the doomed smaller galaxy’s black hole falling to the center of our galaxy, where the insatiable black hole already there would merge with it, growing bigger.

When this happens, so it’s thought, matter in the form of gas, dust, and stars would also fall into the center, feeding the black hole. The matter can pile up outside the hole and get incredibly hot — observations indicate it can reach many millions of degrees, blasting out light in the form of X-rays. Galaxies like these are called active, and we see them everywhere. And many of these active galaxies are weirdly shaped, distorted, indicating they may have recently undergone a big collision. Aha! That fits the idea that colliding galaxies feed black holes and make them active.

There have been so many observations of this that it has matured to become the standard assumption: most active galaxies have recently collided with another galaxy, dumping material into the core and triggering an outburst. I can’t tell you how many papers I’ve read about this, especially when I was working on the public outreach for the Fermi satellite, which was designed to look at active galaxies.

It’s a good story. The problem is, it looks like it’s wrong.

(more…)

A few years back, astronomers discovered that some distant galaxies were blasting out vast amounts of infrared light, but were very faint in visible light, the kind we see. They termed these objects ULIRGs ("you-lurgs"), for Ultra Luminous Infrared Galaxies. The idea is that these galaxies are forming lots of stars, but there was so much dust choking the region that all the visible light was blocked. However, infrared light can pierce through the dust, so telescopes that detect IR can see them. Due to the physics of the situation, astronomers also figured there must be two populations of these galaxies; the ones they had found, and another that was (very) slightly warmer.

Well, they finally found some from that second group:

I know, they don’t look like much, do they? But you have to realize what you’re seeing here: those circled blobs of light are entire galaxies, with billions of stars, and they’re a staggering 11 billion light years away.

That’s really, really far. The Universe is only 13.7 billion years old, so we’re seeing these galaxies as they were just a few billion years after the entire Universe came into being. Not only that, but the amount of infrared light these galaxies are emitting is truly terrifying: in the infrared alone, they are blasting out a solid trillion times the Sun’s entire energy output.

A trillion! 1,000,000,000,000! That’s a whole lot of energy. And it comes from a whole lot of newborn stars, because these galaxies are cranking out stars at a rate 700 times that of our own Milky Way galaxy! The view inside those galaxies must be breathtaking; imagine being surrounded by the Orion Nebula everywhere you look. Wow.

What cracks me up about this too, is how they found them. The European Space Agency is using the orbiting Herschel Infrared Observatory to take a survey of galaxies in the IR. It’s finding a lot of them; in the picture above every dot you see is an infrared source, most likely a galaxy. And that’s a small section of the sky; on the right is an image of a bigger part of the survey. You need to click it and see it full-res to get a sense of how many freaking galaxies there are out there!

As far as astronomical discoveries go, this is another in a long series of steps needed to understand the Universe. I know that in your daily life this may not affect you much; you have other things on your mind, daily stresses and such. But you know what? While I go about my everyday business, in my mind I’m occupied by all the mundane and gross worries of life just like you are, just like everyone else is. But somewhere back there, in some part of my brain, there is knowledge that sits there… and every now and again, it makes itself known.

We can see galaxies a hundred billion trillion kilometers away! We know that stars are being born there, stars like the Sun, and they’re being born every day! If you were there, the sky would be a riot of red and green gas strewn in sheets and ribbons and shock waves and festooned with brilliant jewel-like stars everywhere you looked!

Those wonders are out there, and they’re real. That makes my life better, just knowing that.

Image credit: ESA/SPIRE/HerMES

- Herschel opens its eye
- Herschel eyes the infrared Southern Cross
- Chaos! Turbulence! Blowouts! Herschel!
- Record-breaking galaxy found at the edge of the Universe

Galaxies come in lots of shapes and sizes, but in general, we can group them into four flavors: spiral, elliptical, irregular (no real shape), and peculiar (definite shape, but weird).

We can also say lots of general things for each class: spirals are flat and have lots of gas and dust, ellipticals are spheroids with very little gas and dust, and so on.

The problem is, that pesky Universe of ours delights in throwing a monkey in the wrench. Behold NGC 4696, the confused elliptical:

[Click to galacticate -- and you need to, the above image doesn't give you any idea of just how freaking cool this image is!]

This two-and-a-half hour exposure Hubble Space Telescope image shows incredible detail. The galaxy NGC 4696 is the diffuse glow dominating the right hand side of the image. It sits in the center of the ginormous Centaurus galaxy cluster, a sprawling city of hundreds of galaxies about 150 million light years away.

Clusters of galaxies like this sometimes have one big, fat elliptical sitting in the center. Called the central dominant (or cD^*) galaxy, it generally has far more mass than any other galaxy in the cluster and has weird features (like multiple bright cores, an extended halo of stars, and lots and lots of satellite galaxies). We think these galaxies started off relatively normal, but then eat other galaxies that wander too closely — clusters are thick with galaxies, so such encounters are common. The now-heavier galaxy sinks to the center of the cluster through various forces, where it can really let itself go and eat even more galaxies. That explains the multiple cores (undigestible leftovers), their puffy halos (lots of orbital energy can be added to stars in the collision, inflating their paths), and the plenitude of little satellites (again, leftovers from previous galactic meals).
(more…)

Great beauty in art, it is sometimes thought, comes at the price of great strife. Massive forces, both internal and external, shape the flow of artistry. This metaphor applies equally well to galaxies as it does to humans.

Of course, when the Universe is your canvas, the scale’s a little bigger. Like with this dramatic Hubble view of the spiral galaxy M66:

[Oh yes, you most assuredly want to click that to see the galactic 3906 x 2702 pixel version.]

Mmmmm, pretty. Artistically, I like this shot in particular because of the angle and the way it’s framed; when I look at it I get the impression that it’s looming over me, and I perceive it to be sliding by. The sense of motion frozen in time is palpable.

But then the nerdy science part of my brain kicks in; numbers and physics fill in the back story of the artistry, making the picture even cooler than it looks. That galaxy is as big as the Milky Way: 100,000 light years across. It’s 35 million light years away — 350 quintillion kilometers, more than 200 quintillion miles. It’s also part of a trio of galaxies, the other two being M65 and NGC 3628 — the Leo Triplet. When I was younger, I used to observe them through my telescope in late spring when Leo the Lion was high in the sky to the southwest. They weren’t much more than smudges, but my already-getting-ready-to-be-a-scientist brain knew that I was seeing trillions of stars, dimmed by their unfathomable distance.
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