New Family of Black Holes Found

RobertFisher writes "NASA has just released a press release about an important new family of black holes. From the release, "The previously undiscovered black holes provide an important link that sheds light on the way black holes grow. Even more odd, these new black holes were found in the cores of glittering, 'beehive' swarms of stars -- called globular star clusters -- that orbit our Milky Way and other galaxies." Amazingly, these black holes have a mass proportional to their host cluster, a trend also observed in supermassive black holes ten thousand times more massive. Nature is giving us some big clues here."

How can they tell

[Locke!Erasmus]

that there are black holes there?

Re:How can they tell

[leastsquares]

From the press release:

"Black holes are invisible, but the probing eye of NASA's Hubble Space Telescope found them by measuring the velocities of stars whirling around the crowded cores. Using spectral observations, astronomers discovered that the stars orbiting the cores of M15 and G1 moved at a much faster rate, which suggested the presence of unseen massive bodies."

Re:How can they tell

[Suidae]

Have all black hole detections been done with this method? If so, could it be possible that gravity doesn't work on the large scale the way we think it works?

Re:How can they tell

[leastsquares]

I guess that all black hole detections have been made by such an indirect approach i.e. look for there effects because we can't detect them directly. (They don't conveniently glow like stars ;-) )

It is clear that there is some discrepency between observable gravitational effects and theory at long range. (i.e. the voyager spacecraft are deaccellerating faster than we would expect - and the most likely explaination is due to gravitational theory.)

It is very possible that, on the scale of these galaxies, gravity doesn't behave exactly how we think it should. But I doubt the discrepency is huge.

Re:How can they tell

[leastsquares]

Doh, I meant pioneer spacecraft, not voyager. Whoops.

Re:How can they tell

[clink84]

as a particle gets sucked in, it releases x-rays which are then detected by The Chandra Space Telescope.

not exactly a new family

[jo-do-cus]

as far as i understand, this is not really about a "new family" of black holes, it is just about a certain size of black holes (medium size). Its like french fries: order them small, medium or large, that doesnt make any difference as to the kind of object a french fry is, right? So it isnt about a new family of objects at all.

Re:not exactly a new family

[greenhide]

Yes and no. Because black holes aren't exactly "descendants" of something, it's not like you can say that one kind of black hole is related or unrelated to another kind of black hole.

However, from the tone of the article, it seems that these types of black holes--ones which reside in the center of "globular" galaxies--would have formed differently and at a different time than the larger black holes found at the center of "spiral" galaxies.

I guess a good example is a "pygmy" animal, such as the pygmy shrew [pox.co.uk] (or, try here for a more accurate description [alienexplorer.com]), which is not a "smaller" version of the species but is its own species, related to the normal one.

I'm pretty sure that the conditions for these black holes would have to be different, since otherwise they would have caused the formation of spiral galaxies rather than globular ones. Any astronomers out there care to chime in?

Re:not exactly a new family

[X-rated Ouroboros]

Granted my physics is a tad rusty..

Previously, as I understood, there were small primordial black holes formed very early on in the universe (supernovae concussion wave resonnance and all that fun stuff) and then there were large black holes formed by stars above the Chandrasekhar limit (I.E. there's a lower limit on how small the black holes can be.).

The reason these are exciting is because they're too small to be formed by the normal gravitational collapse of a supermassive star, yet larger than we'd expect primordial black holes to be... and it's a bit flippant to just say they're primordial holes that have eaten a lot.

That's just my semi-educated guess on the matter... the article seems to assume the readers already know why we hadn't previously found any black holes of this size.

Re:not exactly a new family

[Peter T Ermit]

Not quite... the stellar-collapse black holes are a few to a few hundred solar masses, which are lighter than the middleweights. The supermassives, like the ones at the center of our galaxy, are in the millions of solar masses category. The middleweights are in between.

As for primordial black holes, IIRC, they were theoretically allowed to have masses smaller than stellar-collapse black holes, but most models had them at hundreds of thousands of solar masses.

nice choice of words...

[Danse]

The previously undiscovered black holes provide an important link that sheds light on the way black holes grow.

The light was then promptly swallowed into oblivion, leaving the researchers no bewildered and rather annoyed.

RTFM?

[ealar dlanvuli]

One simply has to read the article [cnn.com] detailing how to escape a black hole.

Unfortunatly RTFM might not be an option when your being rapidly dematerialized.

Bang Bang Food's Done.

[Terminus0]

I wonder how big of an explosion it would take to disrupt the globular star cluster enough for the blackhole to eat em all.

Mmm star cluster.

No but really, how delicate do you suppose that balance is between the other stars and the black hole? Can these things stay around for a long time, or would they be pretty temporary things (on an astronomical scale)?

Re:Bang Bang Food's Done.

[Peter T Ermit]

Not much more delicate than the balance between the stars themselves. From a distance, a black hole looks (gravitationally) pretty much the same as a handful of stars bound to each other. It's only when you get pretty close that the extreme curvature of spacetime starts making a difference.

Plus ca change...

[Peter T Ermit]

September, 2002: Medium-size black holes actually do exist, according to the latest findings from NASA's Hubble Space Telescope, but scientists had to look in some unexpected places to find them.

April, 1999 [nasa.gov]: The field of black holes, formerly dominated by heavyweights packing the gravitational punch of a billion Suns and lightweights just a few times heavier than our Sun, now has a new contender -- a just-discovered mysterious class of "middleweight" black holes, weighing in at 100 to 10,000 Suns.

Fudge jesus

[P00PY mcfarkins]

Black holes eh? Back in my day, black holes was just another name for our pootholes since back then, everyone ate blackberry jam