First Science From A Virtual Observatory

mindpixel writes "I first mentioned Virtual Observatories in my July 2000 Slashdot interview. Now, nearly four years later, Spacetelescope.org is reporting a European team has used the Astrophysical Virtual Observatory (AVO) to find 30 supermassive black holes that had previously escaped detection behind masking dust clouds. The identification of this large population of long-sought 'hidden' black holes is the first scientific discovery to emerge from a Virtual Observatory. The result suggests that astronomers may have underestimated the number of powerful supermassive black holes by as much as a factor of five."

Comments

My first question

[AKAImBatman]

Could this by any chance have anything to do with the Dark Energy "antigravity" effect that the universe appears to be experiencing? One would think that the black holes would actually help things collapse, but if they're at the outer fringes, might they be pulling things outward?

Hmm... probably a stupid question, but it never hurts to ask.

Re:My first question

[pe1rxq]

No, the ones detected were in the centre of galaxies...
Also the effects of their gravity are not invisible they have entire galaxies in their grasp.

Jeroen

Re:My first question

[hcg50a]

Could this by any chance have anything to do with the Dark Energy "antigravity" effect that the universe appears to be experiencing?

No. What you're talking about is the motions of distant galaxies.

What the article is talking about is powerful and extremely massive black holes at the centers of certain galaxies, whose centers are obscured by dust.

Using a technique of observing the same objects at widely different wavelengths and correlating the observations, spectra can be obtained, yielding information that implies the existence of the black holes.

This population had been theorized, but not observed until now.

Re:My first question

[AstroAndy]

Black holes are merely supermassive objects of "real matter". They are JUST pieces of matter that pull stuff that come close to it in. They cannot stretch out space by having a bunch of them on the "fringes of space" (which may not exist anyway, seeing as the Universe is most likely infinite). Dark Energy is one sick bastard. It has NEGATIVE pressure. THIS is the best explination to why the universe's expansion rate is accelerating. Black holes have nothing to do with it.

Re:My first question

[mforbes]

Good question, but no. You idea presupposes that there is a center to the universe, from which the galaxies (and the black holes contained therein) have expanded, much like shrapnel from an explosive. Think of it instead as being like points on a balloon as it expands; they're all getting further away from eachother, but none of them can lay claim to being at the center. Therefore there is no point at which one of them is 'outside' the others. Without that vantage point, there is no way to pull.

Re:My first question

[GregChant]

Grandparent is mistaken. Dark energy is just normal energy: it gets its name from a problem that astrophysicists have had since Einstein; if the Universe is expanding, and there is only so much matter and energy that we've accounted for (which, by itself, would cause a "big crunch"), what is causing the expansion?

Astrophysicists call the energy required for such an expansion "dark energy" not because its "evil", but because they can't see it (in the figurative sense).

Re:My first question

[yasmar]

The dark energy refered to is unusual because it implies a kind of antigravity. It isn't drawn into play to account for the fact that the universe is expanding, but rather to explain the recent observations that indicate that the rate of expansion is increasing.

It is related to Einstein's cosmological constant which Einstein regretted introducing because it was kind of a kludge to account for a supposed static universe.

Apparently there are cosmologists today who still regard it as a bit of a kludge, making the cosmological model convoluted like Ptolemy's model of the solar system. There was a recent Scientific American article that discussed this, but only a summary is available online.

Maybe you were confusing it with dark matter?

Re:My first question

[abbamouse]

You are referring to dark matter: the "missing mass" problem. There isn't enough mass to account for the fact the universe is expanding (and apparently is nearly flat). Hence, there must be some form of matter we cannot see, i.e. dark matter.

Dark energy is a second conundrum which does not depend on the mere fact the universe is expanding. It is a puzzle generated by the fact that the rate of expansion seems to be increasing! It's as if something is actively pushing space apart; since gravity grows weaker with distance the push becomes more and more important as the universe expands. Hence the "cosmological constant" -- it would provide a constant push that would initially be overwhelmed by gravity (so the expansion of the universe would begin to slow) but would remain constant everywhere regardless of distance and would thus overcome gravity over very large distances. The result? A universe that goes "bang," inflates rapidly, and then begins to slow down as space expands. Forward billions of years...and the slow expansion starts to speed up again, faster and faster until everything flies a p a r t . . .

Call it what it is:

[JoeLinux]

It's a frickin' database!!

Interesting research

[SIGALRM]

The majority of the sources are so faint that it is currently not possible to take spectra of them and the VO techniques made it possible for the researchers to work seamlessly with images and catalogues from many different sources

One question the AVO may answer is, in this view how do these black holes produce X-ray sources, similar to what we see from galaxies that are much younger?

And (OT) is it just me or does that background hurt your eyes too?

Re:Interesting research

[neilcSD]

more specifically, this one:

http://chandra.harvard.edu/resources/faq/black_hol e/bhole-40.html

That settles that...

[Kid Zero]

It's official: The Universe Sucks! :D

(Couldn't help it)

Re:Dark Matter?

[brilinux]

but it may shed some light

Actually, dark matter does not shed light on anything. That is why it is called dark.

GenBank

[Jonathan]

Not to mention that practically every biology paper involving a molecular sequence includes a search against GenBank, a database of all publicly available sequences started in 1982. Database-based science is nothing new in biology, but we don't call it "virtual sequence hybridization" or some such thing, although database searches have replaced a lot of experimental approaches to sequence similarity measures.

Re:GenBank

[CaptainAvatar]

Well, one major difference I can think of is that virtual observatories will include raw data (eg the AUS-VO has 13 years worth of raw observations made by the Australia Telescope Compact Array). So you can look for things in that data that wasn't dreamed of by the astronomers who took it in the first place. For example, those foreground stars may merely be an irritant to someone looking at that background galaxy cluster, but to a stellar dynamicist they might be very interesting.

As I understand it, GenBank is just a catalogue of gene sequences, which is to say, the end results of data analysis. This is equivalent in the astronomy world to a catalogue of galaxies or stars or whatnot (which virtual observatories will also include). Of course you can get new science from such a database, but it's a very different kettle of fish to making available all the raw data that the geneticists used to derive the gene sequences in the first place, which could be even more useful (well, I imagine so, but perhaps it wouldn't be useful at all to other geneticists). So a virtual observatory is not mere hyperbole, IMHO, because it can be used to make what are effectively "new" observations of astronomical objects, as well as datamine previously compiled catalogues (a la GenBank, or in astronomy, NED or SIMBAD).

Erm, well, I'm rambling a bit so I'll shut up now.

Re:GenBank

[CaptainAvatar]

Well ... I see what you are saying - in genetics, the Gs, As, Ts and Cs are the raw data. Fair enough (although surely there are levels of data more raw than that). But perhaps we are not comparing like with like. In a sense gene sequencing is a subset of chemistry - when you come down to it, these are just molecules - particularly important, fascinating and complex molecules, but molecules nonetheless. But geneticists aren't interested in all molecules, not are they interested in all chemical properties of the molecules they are interested in. Therefore, when they do their thing, they discard anything and everything which is irrelevant to them, abstracting it all down to combinations of G/A/T/C. But there might be other interesting things in their original samples - other new molecules, a cure for cancer, who knows what. In fact, we'll never know, because all we have is a gene sequence and that's all that goes into GenBank. Astronomers do the same; if they are looking for galaxies, they ignore the foreground stars (and vice versa).

But with a virtual observatory, there is no such filtering going on. So you can use that data to look for almost anything you like - asteroids, variable stars, MACHOs, gravitational lenses - whereas an astronomical equivalent of GenBank would only let you look for new galaxies (or some other equally narrow subset of all astronomical objects). Having looked at your homepage I realise that genomics is your field and it's certainly not mine, so I apologise if I have egregiously mischaracterised its scope.

BTW, I enjoyed your scientific genealogy! I can trace mine via P.A.M. Dirac to Ralph Fowler, who as it happens was Rutherford's son-in-law. I also have people like Fred Hoyle, Stephen Hawking and the current Astronomer Royal in my scientific family tree. But as I only have a master's, I am probably illegitimate or something ...

Let me see if I understand this...

[VoidEngineer]

we're using laboratories which don't physically exist to detect things we can't actually see...

hmmm...... somehow this seems like a perverse application of a double negative.

There's a mass of data out there...

[syousef]

...and free software to do data reduction and analysis. Most of it is esoteric and somewhat unintuitive to use, but if you want you can get access to year old observations from

That's exactly what some students chose to do in the internet-taught (distance education) astronomy masters I did a few years ago at the University of Wester Sydney (UWS) in Australia. Unfortunately they've killed off that course but there are courses - online masters degrees and doctorate courses being run out of James Cook University (JCU - http://www.jcu.edu.au) now in QLD Australia. This degree is taught by some of the same staff that created and ran the course at UWS, who left when support for Astronomy by upper management at UWS died in what I consider a disgusting way. They are a good bunch of people, very passionate and highly skilled.

Of course you don't have to do a degree to get hold of the software, and books and try out some reduction yourself. The learning curve is high, but the resources out there on the net for astronomy are amazing.