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Black Hole at Center of Milky Way
kwertii writes: "The Washington Post reports new evidence that there is a black hole with the mass of 2.6 million suns at the center of our galaxy. The Chandra X-Ray Observatory happened to be looking at the presumed site of the hole at the moment it absorbed a comet, blasting x-rays off into space as a byproduct. The implication is that the Milky Way is slowly spiraling down into a giant galactic drain..."
This has been a pet belief of mine for some time, as it is hard to see how a galaxy could form and survive without a ridiculous amount of mass gathering at the center.
My question is what is the approximate size (diameter) of this black-hole and what is its density. I assume its not particuarly dense just particuarly big.
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A mass of 3 million Suns may seem a lot, but it isn't when you remember that the Galaxy is quite a bit bigger than that. It's unlikely that this Black Hole could "swallow" the galaxy, in fact it's probably the only reason our galaxy exists.
Incidentally, the BBC article is here.
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I wonder if these effects will cancel each other
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If you were blocking sigs, you wouldn't have to read this.
I'm probably completely wrong here, but as you go near a black hole doesn't time not slow down, so to us this comet going into hole should last forever... or something???
" The implication is that the Milky Way is slowly spiraling down into a giant galactic drain... "
Do we get to see Mozilla 1.0 before that happens ?
Heh.
>By a stroke of good fortune, NASA's Chandra X-ray Observatory satellite happened to be looking when the presumed black hole enjoyed a quick snack of gas and dust.
:)
give or take a few million years... light does take a little while to reach us from the middle of the galaxy you know
//rdj
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Nothing is seen past the event horizon of a black hole. Beyond that, there are great masses of rotating gasses becoming enormously compressed orbiting their way around and falling in towards the black hole. These massively compressed gasses, dust, etc. get so incredibly hot that unfathomable amounts of energy are released well outside the event horizon. This energy can escape and be seen.
Apparently he did hear a giant sucking sound!
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I was certain that absolutly nothing could escape a black hole, so im wondering how x-rays could be seen as a result.
of course my elementary school astronomy level excuses for that knowledge
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They're talking about a clump of matter in the accretion disk that isn't quite ready to go down. But yes, we would never see the moment the clump actually crossed the event horizion. We would get to see it get closer and closer to the event horizon at lower and lower frequencies, but never cross.
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I saw a BBC "Horizon" about this the other day on a flight. They talked a lot about "feeding" of apparent suppermassive black holes that they think live in (probably all) galactic centres.
Apparently they stop "feeding" after a while because the mass of the surounding matter in the galaxy means it won't fall in. The attraction from the black hole is balanced, so the matter orbits the hole. Anything itinerant -- like a comet say -- that passed near the hole slowly or closely enough would still get swallowed, but most of the galaxy should stay intact.
Of course, that's iff nothing else intereferes. The Andromeda Galaxy is heading our way, so in some (distant) future time matter in it will become a significant gravitational influence on matter in our own Milky Way. That should upset the balance, and researchers are hypothesising the disruption setting off feeding of the black holes at the centre of both galaxies, which will go on to swallow up large portions of each galaxy.
Should be quite a show.
Bah ... just launch 40 nova bombs into it and we are save again ;)
> particuarly big.
I guarentee it, sonny. That thing is dense. Reeeeally damned dense. It's downright doubly damned dense. I bet billions of pounds of gas and dust are probably being sucked past it's event horizon for every character I write. You should never play down a black hole sitting at the middle of a galaxy 100,000 light years across with possibly 1 trillion stars in it.
Probably though it is not as dense as someone who assumes a black hole isn't.
For any developers out there that want to see what this is really capable of you've got to check out http://www.square1.nl, these guys have put together a really nice gallery.
I grabbed a GoLive license as soon as I saw this stuff!
This is nothing new. I've had this photo for a while: Black Hole at the center of the Milky Way.
"This hipothesis of a giant blach hole at the center of the galaxy is really interesting... too bad we won't have the galactic center exploding, as in Larry Niven's "Known Universe" books."
You mean the center of the universe. And we can't look at the "center" of the universe all that easily because that would require pointing our telescpes in a direction that is perpendicular to everything.
is it 'draining' clockwise or counter-clockwise?
can we switch from 'suck' to 'blow'?
My understanding for quite some time had been that current theory was that there was a super-massive black hole at the centre of every galaxy, and in fact that they were required for the formation of galaxies...
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That's not at all the implication, and the article doesn't say that either. It would be nice if the slashdot editors didn't repeat everything that was submitted literally, since in this particular case, the bit about the "giant galactic drain", is simply bullshit, and obviously the brainfart of someone who doesn't know the least bit about black holes, gravity and orbits.
no, he means the center of the galaxy. What are you thinking of?
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KIRK (alarmed) The center of the galaxy?
SPOCK There Sha Ka Ree is fabled to exist.
KIRK But the center of the galaxy can't be reached. No ship has ever gone into the Great Barrier. No probe has ever returned.
SPOCK Sybok possessed the keenest intellect I have ever known.
KIRK Spock! My only concern is getting the ship back. When that's done and Sybok is in here then you can debate Sha Ka Ree until you're green in the face. Until then, you're either with me or you're not.
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News for nerds, indeed.
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Correct me if I am wrong but isnt a black hole a 'dead' star, while the sun is yet 'alive' and all the black hole effects are seen only when the star runs outs of its fuel?
My question is can a black hole grow infinitely?
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This gives a new meaning to "FLUSH".
:)
Now I wonder if it's clockwise or counter-clockwise
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Does anybody here know about the work that is being done on gravity waves? I remember going to a seminar in college where Kip Thorn, a physicist out of Berkley I believe, spoke about his theory of gravity waves. I think these were small ripples in space-time that were supposed to be caused by black holes. The idea was that if they could be measured then it would prove the existance of black holes. I don't remember the particulars, I just went because it gave me extra credit for my Differential Equations class. But it seems that this work is now superseeded by these images from the observatory.
What's a Sig???
Or approximately infinite.
Density is defined as d = m/v (m is mass, v is volume.)
The volume of a singularity (the object at the center of a black hole) is effectively zero, so the density of the singularity is undefined (though commonly said to be infinite).
When the diameter of a black hole is referred to, they are most often talking about the Event Horizon, the boundary around the singularity from which nothing can escape, not even light.
Note that the distance of the event horizon from the singularity is determined by the mass of the black hole, not the density or volume (since density and volume for ALL singularities are effectively equal). Gravity is still dependent on mass, and the event horizon is simply the region of space where the escape velocity from the singularity's gravitational pull exceeds the speed of light.
(on a side note, since the only real requirement for a black hole is to have zero volume, anything could become a black hole if compressed enough.)
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when you get to the Wedge.
I've heard before that galaxies don't rotate right, that the core and outer velocities are not "correct" with respect to each other. This has been mostly in connection with dark matter and missing mass. I wonder how supermassive black holes affect this apparent mismatch. (for better, or worse)
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From my understanding, a black hole will dissipate energy in the form of gamma/X-rays throughout its life. If the hole is not actively 'feeding' it will eventually dissipate (conservation of energy and all that). (I doubt a hole the size of this one will dissipate in any reasonable amount of time though.)
Of course, this is from my reading of Earth by David Brin, so I may be totally off kilter.
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Beowulf Schaeffer has known this for a while :)
Now all we have to do is follow the puppeteers out of here
I always thought that a black hole, by definition, has infinite density, and zero diameter.
Now the size of it's event horizon is a different matter...
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read the story before submitting your post - just because it says 'comet sized' does not mean it was a comet.
Awesome!!!!!
maybe the chandra x-ray observatory will find chandra levy in that black hole too...:-\
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The density can be calculated two ways. The real density is infinite (all the mass is at a point in the center)
Apparent density (which is the only density you can really calculate) varies proportionally to M/R^3 where M is mass and R is the radius from the center to event horizon. But with black holes, R is directly proportional to M (R=2GM/c^2). So this "density" falls off as 1/R^2 or 1/M^2 (take your pick). But this is not real density. Remember the "volume" is proportional to M^3. But this isn't the hole's own volume. It's the volume contained within its event horizon, which is much different.
The surface gravity at the event horizon can be arbitrarily low, because it varies INVERSELY with the mass of the hole: g=(c^4)/(4*G*M). A 2-million-sun black hole has a mass of 5.2x10^36 kg. I get a "surface gravity" (at the event horizon) of about 6000 g when I plug that in. (This is about 7.7 million km from the hole.) Which is pretty sad, actually. Surface gravity at the surface of a mere sun-sized black hole would be 2.6 million times greater than this. But you would have to get much closer to the smaller hole to reach its own event horizon. A small black hole's field falls off very quickly because the mass is comparatively small. A supermassive black hole, OTOH, has a relatively weak field that persists in strength for many light years outward.
For a black hole to have a surface gravity of about 1g, it would need to weigh as much as 16 billion stars (only a few percent of the mass of a typical galaxy). Such a hole would have a radius of 50 billion km (about 1/3 of the distance from the Sun to the Earth). The hole in M87 is only about half this size. Meaning that you would experience a surface gravity of 2g at the event horizon, and you would probably not even realize you fell in for several hours after wandering inside- unless you could look through your spaceship's window and see the weird optical effects on stars. By the time you would experience the "spaghettification" effect from tidal forces, you would almost be at the singularity anyway. A smaller hole can spaghettify you before you even cross the event horizon.
And what do you mean by "modulating your personal frequency"? What frequency is my personal frequency? Do I have to register it with the FCC?
Perhaps you mean the effective frequency associated with all matter particles, due to the wave/particle duality of matter? Which of the billions of particles that make up my material self shall I choose to represent my "personal" frequency? That frequency can't be modulated, however, so I don't know what you mean...
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Only stuff that goes very close to the center of the galaxy can get sucked into the black hole - i.e. only matter with a very low angular momentum (relative to galactic center.) The total angular momentum of the system is conserved, so there is only so much you can feed the hole before you 'run out' of 'low angular momentum'. This is a likely reason why such black holes cause quasars in young galaxies, but they aren't being fed fast enough to do this in older galaxies.
I expect that if you could let the galaxy run for long enough (ignoring collisions with Andromeda, exhaustion of fuel for stars, proton decay, evaporation of black holes etc.) you would end up with some fraction of the mass eaten by the hole and the rest in circular orbits in a flat disk - as this is the minumum energy configuration for a given amount of angular momentum.
Actually, if you're prepared to wait a really long time, the angular momentum will be shed by gravitational radiation and the black hole wins after all. (Or would, if it hasn't evaporated.)
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Hey, I saw some things on here which aren't entirely correct, I just wanna set the record straight.... no evil intentions or attempt to anger anyone is being made.
;)
1)Nothing is seen past the event horizon of a black hole. Beyond that, there are great masses of rotating gasses becoming enormously compressed orbiting their way around and falling in towards the black hole. These massively compressed gasses, dust, etc. get so incredibly hot that unfathomable amounts of energy are released well outside the event horizon. This energy can escape and be seen.
-> Once something (gas, dust, small planets, etc) has passed the event horizon you will see nothing from it. The idea of the event Horizon is that at that point the escape velocity is the speed of light. As matter cannot reach this (thank Einstein) once it passes, it's gone. this also works for light, the speed of light is constant, once it passes the event horizon, it ain't coming back either. what we see from Chandra is photons(X-rays) that have been released PRIOR to some chunk of mass passing the event horizon.
2)Does anybody here know about the work that is being done on gravity waves?
-> try checking out LIGO (Gravity wave observatory just now coming online)
http://www.ligo.caltech.edu/
3)I assume its not particuarly dense just particuarly big.
-> Black holes are by nature very dense. They have vary large amounts of mass stuffed into very small areas. For instance a small blackhole usually consists of several times the mass of the sun stuffed into an area of roughly the size of New York city.
4)is it 'draining' clockwise or counter-clockwise?
-> depends from which side of the galaxy you look at it...from above or below?
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This happened 27,000 years ago.
I've noticed that some people have a bit of confusion here about exactly what the effects of a black hole are. Here's are examples:
Q: What would happen to the orbit of the earth if all the matter in the sun were suddenly compacted into a black hole?
A: Absolutely nothing. A black hole which contains the mass of the sun would still also have the same gravity as the sun. The earth would continue to orbit as it always has.
Q: The galaxies stars orbit around the black hole.
A: This isn't proven. Some galaxies don't have any evidence of a black hole, yet theirorbit around a center of mass. In any case, the black hole at the center of our galaxy is 2.6million solar masses. This is NOTHING compared to the billions of stars in the galaxy, so the effect of the black hole of the actual shape and orbit of the stars is not significant.
Q: Doesn't it sound like someone has pulled the stats on this black hole out of their arse?
A: Not really, the size of this black hole has been measured in several ways, including observing very high velocity stars near the black hole. The motion of these stars betrays the existence and size of the massive object at the galaxy's center.
Q: Aren't black holes required for the formation of galaxies?
A: We don't know for sure yet. There are galaxies without black holes, so it might not be required. Of course, we might just not be detecting the black holes that are in those galaxies.
If tits were wings it'd be flying around.
...at the center of the galaxy, why can't they point the Chandra X-Ray Observatory down and find the black hole that Chandra Levy fell into?
Galactic dynamics is a very interesting subject. One of the first things you discover are orbital resonances. Currently there are several theories that attempt to explain the propogation of the spiral structure in terms of resonances with the orbit of the aspherical central bulge.... And in the case of barred spirals, there has even been some success in modeling this (the bar structure is easier to model). None of the current theories ascribe the spiral structure to simple orbital decay (in fact, galaxies would look a lot different from spirals if significant orbital decay were present).
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i dont think it's because the black hole itself produces the xrays, but rather the energy of the object that is being crushed into itself -- like compacting yourself to the size of a spec of pepper -- you gotta get rid of a whole buncha energy.
as for the size of a blackhole -- i believe they are extremely dense "points" -- fractions of the size of their event horizon and such. something so dense that even LIGHT cannot escape it is pretty amazing, and since gravity affects everything, it would also affect itself -- in turn crushing itself in the process!
hope this helps
Here are the articles the popular press cited (very awkward registration required). The "news and views" piece explains that astronomers previously thought the galactic core might be as much as 1500 times as wide as the event horizon of an equally massive black hole. The new observation indicates that it's no more than 20 times as wide.
Not necessarily. By the definition in the grandparent, a black hole is the interior of any closed simple surface-- the event horizon-- through which escape velocity equals c; this does not necessarily imply the presence of a singularity within its bounds. As distance approaches infinity, the gravitational effect of an arbitrarily shaped non-point distribution of mass approaches the effect of a point source of gravity with the same total mass (in other words, a singularity) at the center of mass of the original distribution. The spacetime distortion created by internal gravity effectively makes the distance to the event horizon from any point inside infinite-- therefore making any distribution of mass inside indistinguishable from any other distribution, including a singularity, when viewed from outside.
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Washington Post reports that Jimmy Hoffa is still missing! Haven't we known this for a long time now?
what? like the universe?
I think u've skipped a step somewhere
I suppose that given that everything is made up of everything else, and there are some blackholes in this universe, then you could argue we are part of a huge black hole, just outside of it's event horizon?
Really tho it's the event horizon that counts.
'There is a Light that never goes out.'
Gee, so you mean to tell me that there is something of great gravitational force holding my galaxy together???
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Well, I guess colloquially "light" is used to refer to the visible portion of the spectrum only, but technically, light is any form of electromagnetic radiation, from radio to gamma rays...it's all made of photons, and it all travels at c; the different "categories" differ only in frequency (ironically enough).
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This has been theorized for years now. I seem to remember several years ago a report that suggested that they had found a stream of "space smoke," if you will, that could possibly be feeding this blackhole... which coincidentally was also proving it's existance in the first place.
Am I the only one who thinks this is old news?
"The implication is that the Milky Way is slowly spiraling down into a giant galactic drain.."
Nonesense. That's like saying the Solar System is spiraling down into the sun.
Don't quit your jobs yet.
And while we're on the subject, how many licks does it take to get to the center of the Milky Way?
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It seems that our universe is constructed such that any intelligent organisms will quickly gain powerful proof that black holes are real and (eventually)unavoidable entities, and thus that there are multi-local places where matter leaves this universe, on a one way trip. Supermassives are the easiest to see, but it is my expectation that we'll gain much more evidence for the multi-local presence of ordinary black holes in years to come. The most interesting question seems to be not whether or not we will *ultimately* end up in a black hole, but rather *how quickly* we are headed there.
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Major Speculation Warning:
As many of my readers know, I see black holes (the garden variety ones, not the rare and easily observable supermassives) as the most reasonable candidates for the transcension of complex civilizations. This scenario very nicely explains why we haven't been colonized by robotic Von Neumann probes from other clearly ubiquitous civilizations in our galaxy, even though the galactic core is many billions of years older than us, and we are a mere 30,000 light years away from it. If Eric Chaisson, Seth Lloyd, and others are right, the developmental computational destiny of all complex systems appears to be the exponential approximation of black hole density with our computational architecture (ie, macro, meso, micro, nano, femto, black hole computational substrates). It's a short leap from this to realize that the whole universal system may be built for accelerating computational transcension, with black holes as the most likely multi-local endpoints and portals. As I argue in my forthcoming book, Destiny of Species, we may be perhaps twenty or thirty years away from theoretically (and eventually, experimentally!) proving a black hole destiny for all complex systems in the universe, as they head off to some even more complex environment within the multiverse. Keep your eyes open. Whatever we find, it's guaranteed to be a fascinating story...