Starship Asterisk*

Arp 299: Black Holes in Colliding Galaxies

Explanation: Is only one black hole spewing high energy radiation -- or two? To help find out, astronomers trained NASA's Earth-orbiting NuSTAR and Chandra telescopes on Arp 299, the enigmatic colliding galaxies expelling the radiation. The two galaxies of Arp 299 have been locked in a gravitational combat for millions of years, while their central black holes will soon do battle themselves. Featured, the high-resolution visible-light image was taken by Hubble, while the superposed diffuse glow of X-ray light was imaged by NuSTAR and shown in false-color red, green, and blue. NuSTAR observations show that only one of the central black holes is seen fighting its way through a region of gas and dust -- and so absorbing matter and emitting X-rays. The energetic radiation, coming only from the galaxy center on the right, is surely created nearby -- but outside -- the central black hole's event horizon. In a billion years or so, only one composite galaxy will remain, and only one central supermassive black hole. Soon thereafter, though, another galaxy may enter the fray.

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In visible light, Arp 299 looks like this. In the image at left, it would be the upper left galaxy (NGC 3690A) that has an active black hole.

Ann

Ann wrote: In the image at left, it would be the upper left galaxy (NGC 3690A) that has an active black hole.

Sorry for asking a simple question, but what is the difference between an 'active black hole' and an 'inactive black hole'? Or was the wording just descriptive?

Guest wrote:

Ann wrote: In the image at left, it would be the upper left galaxy (NGC 3690A) that has an active black hole.

Sorry for asking a simple question, but what is the difference between an 'active black hole' and an 'inactive black hole'? Or was the wording just descriptive?

An active black hole is a hole that is currently consuming matter. A torus of material forms around it, and matter spins faster and faster in that torus, heating the matter to very high temperatures. Eventually the matter crosses the event horizon of the black hole and is effectively "lost" from the rest of the universe. The black hole emits jets when matter falls into it.

An inactive black hole doesn't do much at all. It just sits there.

Ann

Ann wrote:

Guest wrote:

Ann wrote: In the image at left, it would be the upper left galaxy (NGC 3690A) that has an active black hole.

Sorry for asking a simple question, but what is the difference between an 'active black hole' and an 'inactive black hole'? Or was the wording just descriptive?

An active black hole is a hole that is currently consuming matter. A torus of material forms around it, and matter spins faster and faster in that torus, heating the matter to very high temperatures. Eventually the matter crosses the event horizon of the black hole and is effectively "lost" from the rest of the universe. The black hole emits jets when matter falls into it.

An inactive black hole doesn't do much at all. It just sits there.

Ann

So an inactive black hole basically 'doing nothing', would not be detectable. Would this be considered dark matter?

Guest wrote:So an inactive black hole basically 'doing nothing', would not be detectable. Would this be considered dark matter?

You can detect an inactive black hole by its gravitational influence on surrounding visible matter. This video shows the measured orbits of stars in the center of the Milky Way. They orbit around an invisible mass. From the shape and period of the orbits, astronomers have inferred the mass of the central black hole in the Milky Way to be about 4.3 million solar masses.

Similar to inactive black holes, dark matter can only be detected by its gravitational influence on the orbit of visible matter. But the measured effect of dark matter on the orbits of the stars in galaxies cannot be explained by black holes. For instance, dark matter is distributed on a large scale, whereas black holes are "point like" and effect only their nearest surroundings.

Tangled or entangled two black holes encountering each other are bound to be… out of this universe?

http://asterisk.apod.com/viewtopic.php?t=34319

Tale of Two Black Holes - Credit: NASA/JPL-Caltech/GSFC

"their central black holes will soon do battle themselves". Wondering how "soon" that is.

"their central black holes will soon do battle themselves". Wondering how "soon" that is

Are we so sure the galaxies and their centers are doing battle? Perhaps they are in love, and we are seeing the foreplay, and at some point in our distant frame, but not theirs, there will be a stargasm...

It's a Feeding Frenzy....

awesome pic...
:---[===] *

zendae1 wrote:

"their central black holes will soon do battle themselves". Wondering how "soon" that is

Are we so sure the galaxies and their centers are doing battle? Perhaps they are in love, and we are seeing the foreplay, and at some point in our distant frame, but not theirs, there will be a stargasm...

Come on... Really. My kids read this...

zendae1 wrote:

"their central black holes will soon do battle themselves". Wondering how "soon" that is

Are we so sure the galaxies and their centers are doing battle? Perhaps they are in love, and we are seeing the foreplay, and at some point in our distant frame, but not theirs, there will be a stargasm...

It would SEEM to be attraction, and we do FALL in love....

:---[===] *

Hey, that is true but did you know you that magnets are also attractive? It looks like they are magnetically combining in the red/blue/green bandwiths.

Guest wrote:

zendae1 wrote:

"their central black holes will soon do battle themselves". Wondering how "soon" that is

Are we so sure the galaxies and their centers are doing battle? Perhaps they are in love, and we are seeing the foreplay, and at some point in our distant frame, but not theirs, there will be a stargasm...

Come on... Really. My kids read this...

So, which imagery bothers your children? The idea that one galaxy and another are attracted and merge, or that one galaxy consumed the other? I find the former a more valid depiction in my mind, but in neither case do I see a reason to be worried for your children's sensibilities. ("Avert your eyes, Junior, a raindrop just landed in a puddle!")

Is it perhaps the use of the terms "foreplay" or "stargasm"? If young children asked me what the poster meant by such terms (the term "stargasm" actually not being a bona fide word at all), I could easily answer them without mentioning anything a Puritan should find objectionable. Or were you just being funny yourself? But you wrote "... Really." Or was that word meant to be as in: [youtube]D2MPoqqzwdY[/youtube]

Some people really don't like sexual innuendo of any sort, Mark. This is supposed to be a family friendly site, but I don't personally think you really crossed a line. I got chided a while back for offering the advice, "Don't be a dick." because it had the d-word in it, so I feel your pain.

geckzilla wrote:Some people really don't like sexual innuendo of any sort, Mark. This is supposed to be a family friendly site, but I don't personally think you really crossed a line. I got chided a while back for offering the advice, "Don't be a dick." because it had the d-word in it, so I feel your pain.

I find that what is deemed acceptable and what is not highly depends on ones culture. Quite explicit sexual images are used in public advertisements, commercials and movies here in Germany, which would be deemed as highly inappropriate in the US. On the other hand, Germans have more issues with violence in movies than US Americans do. And then I heard that Chinese don't approve the showing bones or skeletons, which neither Germans nor US Americans seem to have a problem with...

Hmmm ... it seems I need practice with youtube embedding.