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Baby Black Hole With Big Appetite
kuni ito writes: "'According to the astronomers who detected the object with Japan's Advanced Satellite for Cosmology and Astrophysics (ASCA), the black hole seems to be acting like a supermassive black hole, despite its size. It's sucking up matter at roughly the same rate as its much larger (and seemingly less hungry) relatives, they said.'" This black hole (assuming that black holes exist) seems to be eating a lot more than would otherwise be predicted.
Infinite mass -> infinite gravity -> nignificant (infinite?) gravity at infinite distance.
Bill - aka taniwha
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Bill - aka taniwha
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Leave others their otherness. -- Aratak
Actually, from what I've read, the time it would take for the black holes to completely consume everything was longer than the time it would take for the Universe to stop expanding and fall back into itself (the so-called Big Crunch).
So, there's no need to fear being eaten alive by black holes billions of years in the future. Just watch out for all of the galaxies coming straight at you from every corner of the Universe. One word of advice: duck!
Tongue-tied and twisted, just an earth-bound misfit, I
Learning to fly, Pink Floyd.
The report seems to be that this thing is eating more than a teenage BH should be. But given the way they eat (everything from light on down) wouldn't this just mean that it ran across a particularly dense "meal"?
And because it's fairly fundamental to my Theory of Everything, do BHs grow as they eat?
oh, and Space.com lost about forty points on my credibility scale with this link under the story
"Aliens Among Us -- Which celebrity is really an alien? You decide! "
They trying to muscle in on the Weekly World News?
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+&x
Basically, what I was talking about doesn't have that much to do with the temperature of black holes or the evaporation of black holes.
What you want to know about is Hawking Radiation, as this is actually related to both of your questions. I suggest you grab a copy of Stephen Hawking's A Brief History of Time and read on hawking radiation. If you could get a copy of the illustrated brief history of time, even better, as I've found that book easier to wade through. I'm not going to try to explain hawking radiation, as a physicist friend of mine (not from caltech) yelled at me that what I was saying about hawking radiation would confuse people. Besides, Professor Hawking is far more elegant than I am.
Moller
Okay, I'm gonna admit it - I am a physicist. At least that's what my degree says, anyway. I just though it might be helpful to explain what I got from it. Sadly, it the article was kinda lacking in details, but this is what I gathered.
Basically, a black hole is a big old sucky thing. It pulls in everything around it. Since the stuff can only fall in so quickly, the stuff spends a lot of time whirling around the black hole before it falls in. While it's whirling around, it tends to bump into the other stuff that's similarly whirling.
Now, with all that whirling and bumping, some of the stuff gets turned into x-rays (E=mc^2, remember?).
Now, the stuff that got turned into x-rays doesn't make it into the black hole, which is useful 'cause that's how we detect the things in the first place.
With a bigger black hole, there's a lot more whirling and bumping going on, so less of the stuff that the black hole starts out sucking on makes it into the Sarlac pit - I mean black hole (sorry, just re-watched ROTJ).
That means that with a smaller black hole, a bigger proportion's gonna make it into the black hole itself.
At least, that's what I got from the article. But then, my specialty's nuclear physics...
"If God created us in his own image, we have more than reciprocated"
I don't think we can say that the black hole is rotating. The singularity is a point with (effectively) zero volume, and I would say that this precludes it's ability to rotate.
Since the singularity has zero volume, it must exert its gravitational force equally in all directions. Perturbations in a gravitational field would arise from unevenly distributed mass within a given volume. Since we have no volume, we can't have an uneven distribution of mass.
Moller
Um, that's not correct, is it? I thought that the stuff whirling around is whirling so fast that when it bumps into other stuff, the energy from momentum is what's being given off as x-rays. The stuff itself is not destroyed (converted into energy) but rather slowed down. Unless you're suggesting that there's nuclear fusion happening, which I suppose is possible.
...phil
...phil
"For a list of the ways which technology has failed to improve our quality of life, press 3."
What I find interesting is how they say its a "small" black hole thats gobbling up "lots of stuff". Yet the only way we have of detecting black holes is through the amount of x-ray radiation that escapes at the poles, and heating of dust as it rotates and falls inward.
A black hole that has contradictory data about its size would obviously point to the existence of a seperate unidentified object.
I don't think we could all get more confused than that article left us, but let me try by asking a few questions:
The article is trying to reveal something surprising, but which is it:
That mid-mass black holes are just as INefficient as super-massive black holes, thus bringing an unexpected phenomenon into a new realm of scale?
or
That mid-mass black holes are just as powerful, and thus considerably MORE efficient than, super-massive black holes, thus limiting the odd inefficiency of super-massive black holes to only the highest mass scales?
In any case, I don't think it means that the mid-mass black holes are inexplicably efficient.
Some questions about the low-efficiency super-massive black holes:
Doesn't the mass that gathers around these holes "dilute" the gravitation as you get closer to the black hole, and are surrounded by mass in all directions? Assuming this has been accounted for, how much more inefficient are these holes than expected?
Could the supermassive black holes be decaying, thus weakening the rate at which new mass gathers, while still being surrounded with the mass and radiation to be expected from their large initial mass? Isn't decay a prediction of Hawking's?
Lame-ass speculation is of course perfectly welcome in lieu of real answers...
"You can't get something for nothing." - my grandfather, on the stock market and Reaganomics.
because as far as you are concerned, whatever you are watching falling into the black hole never actually falls into the black hole. Because of the time dilation that an object experiences as it falls into a black hole, we never see it actually fall into the black hole.
To use an example from Stephen Hawking's A Brief History of Time:
Suppose that you are watching an astronaut fall into a black hole. Suppose that you can see the watch on the astronaut's wrist. As the astronaut approaches the event horizon, the seconds will start ticking off slower and slower. Actually, each second will take twice as long as the one before, until finally, before the astronaut passes the even horizon, the last second on his watch will take an infinite amount of time to elapse (from your viewpoint). Of course, the astronaut notices none of this, and time passes normally for him as he flies through the event horizon to his death.
This is a consequence of special relativity. In your reference frame (the observer's frame), the astronaut will never actually pass the event horizon. But, since the speed of light is equal in all reference frames, you can still see him because light is still reflecting off of him as far as your concerned.
And the light doesn't grow "Dimmer" as you get closer to the event horizon. The light still has the same intensity, it isn't like the black hole is sucking photons off of their course out of light rays passing by, the event horizon is more like a "curtain", on one side light is passing normally (normally enough, it isn't slowing down, just "curving" because of the warping of space-time around the black hole), and on the other side of the event horizon, light spirals into the singularity, never to escape.
Hope that elucidates things.
Moller
From what I've read, a black hole is a singularity with mass. That is, it has mass but not size, it is a one-dimensional point. The only measurable property that a black hole has is mass.
Perhaps you should try reading more on the subject, since you seem to be a bit mistaken on black holes' propertiese. For starters, black holes may have a net electric charge and (if magnetic monopoles exist) a net magnetic charge. They may have a net angular momentum as well. All of these, in principle, are observable from outside a black hole's event horizon.
Furthermore, a black hole singularity does not need to be a single point. In the case of a charged, rotating black hole, for instance, the singularity is ring-shaped and has the curious feature that if you were to travel through the center of the ring it's anyone's guess where you would end up. You could, in principle, find yourself in a universe that is on a different "Riemann sheet" than the one we are in now that is connected to our universe through the little bridge of spacetime at the center of the ring singularity. Except for the untidiness of inevitably finding oneself inside a black hole's event horizon in the "parallel universe," this piece of physics seems tailor-made for science fiction.
From a practical standpoint you are correct, however. In 99% of the problems in astrophysics nobody gives a hoot what the esoteric properties of a black hole are. It's just a compact critter that radiates x-rays like crazy when it gobbles up matter. (A notable exception to this is people who study accretion in quasars, where assuming a Kerr geometry instead of a Schwartzchild geometry can affect accretion models by a noticeable amount).
Black holes can be detected (in theory of course) by looking for the emissions they give off. The theory goes (extremely roughly) that as individual particles reach the "edge" (event horizon?) of the black hole (crossing this line means you never come back), some of them are torn apart, half of the particle going in, half going out, and some energy is released during this fission. It is these fissions at the edge that make a black hole appear to give off energy, and make it detectable.
That type of radiation is called Hawking Radiation (after Stephen Hawking, naturally). However, this isn't what lets us detect black holes, as Hawking Radiation is ridiculously faint. Black holes can be detected by the X-Rays that they "inadvertantly" produce. When matter is falling into a black hole it is accelerated, heated, and compressed to such a degree that it gives off large amounts of X-Rays. I believe the first black hole we detected (again, assuming black holes exist), was Cygnus X-1 (or cygnus something), and we detected it by the x-rays it gave off.
Another method of detecting black holes is to look for graviational lensing effects. Because black holes are so massive, they bend the fabric of space time. (Imagine a sheet suspended in the air. Place marbles on the sheet. The marbles make depressions on the sheet, like stars make "depressions" in space-time. A black hole is so heavy, it's like dropping something that is the size of a marble but with the weight of a bowling ball onto the sheet. The sheet bends A LOT, and it actually will have a hole where the singularity is.) Light travels in a straight line, so if space-time curves, light also curves with space-time. Gravitational lensing was proved during a solar eclipse. Astronomers observing the eclipse noted that they were able to see stars that should have been blocked by the eclipsed sun. The sun's gravitational field caused enough "lensing" so that stars directly behind the star could be seen to either side of the star. So, if we find something out in space that is causing a LARGE amount of gravitational lensing, but we can't see anything, there's a chance it's a black hole. At that point we normally observe it more to determine if it is or isn't a black hole.
Moller
IIRC, Hawking radiation deals more with the evaporation of very small black holes. This explains why there are no microscopic black holes, as they should have been formed in the Big Bang, but we dont detect any because they have 'evaporated' over billions of years. Hawking radiation does not appreciably affect the mass of black holes formed by collapsing stars, which is how most black holes are formed.
IANAAP (Astro-Physicist)
From what I've read, a black hole is a singularity with mass. That is, it has mass but not size, it is a one-dimensional point. The only measurable property that a black hole has is mass.
Mea navis aericumbens anguillis abundat
First, you would see a very funny-looking accretion disk and some very strange radiation patterns.
You'd see massive Doppler shifting from the x-ray spouts, not unlike our observations of the binary pulsar in (I think) 1974.
Black holes wouldn't rotate around each other for long -- in their case, the gravitational radiation would be enormous, causing the system to radiate energy away until they collapsed into one another.
Finally, no wrinkles to special relativity. Gravity's pull would relate to general relativity.
10^70 to eradiate a black hole 3 diameters of our planet. BTW. for all the protons in the Universe to decay it's only 10^30 so we will never see a black hole eradiate since all the matter will decay way before that time
You can't handle the truth.
Black Holes and Beyond
Black Holes: Mystery of the Cosmos
Black Hole: The Death of a Star
Shit Load of Links
Any similarity to a real person is purely coincidental
What's the deal with the event horizon? All the pictures I've seen (admittedly, many from science-fiction) depict a circle, and stuff gets sucked through it like a gate, and funnels downward (so the circle becomes the base of a sort of curvy concave cone shape).
That's the accretion disk that is being depicted. The accretion disk is a vortex of matter that is spiraling into the black hole, getting ionized, energized, and putting out a lot of x-rays along the way. That's why sci-fi artists love to show the accretion disk. You can have a lot of fun and make it look really cool.
So, why isn't the "event horizon" (a distance from the actual point of the hole) a sphere extending the same radius in all directions?
You can't "see" the event horizon. The event horizon is where light can no longer escape and by definition puts out no light. All you would see is a black hole in space -- hence the name "black hole." If you see something fall into a black hole, you would't see it actually hit the event horizon; it would merely keep falling in more and more slowly.
In any case, the event horizon tends to be quite small. If you collapsed the Earth, for example, into a black hole, the event horizon would have a radius of just one inch. Only a supermassive black hole of millions or billions of solar masses (the kind you have at the center of big galaxies like the Milky Way) will have large event horizons.
Does this
Bill Gates would be a suitable name for it.
Fh
*ducks*
What do I do, when it seems I relate to Judas more than You?
Still not dead.
I'm no astrophysics major, but here it goes...If these things are sucking up so much matter, do they not become more massive, and thus have even more gravitational pull? Basically, are they getting stronger as time passes? Do black holes in general get stronger? I consider myself an astronomy guy, but I'm afraid my knowledge of black hole theory is limited to how we detect them (provided, of course, they are what we think they are).
"The universe seems neither benign nor hostile, merely indifferent." --Carl Sagan
Now, this is mainly just from my understanding of black holes having read Hawking's Brief History of Time and taken one astronomy course. But I don't remember ever reading about the light redshifting to infinite (if you could explain that in more detail for me, I'd be grateful).
Perhaps he or she just meant that the light would redshift beyond the visible spectrum into the infrared range?
And I'm not sure how you're using "corpuscular," I've never heard it used that way.
That surprised me at first too. So I checked Noah and it turns out that corpuscular can be used to refer to a stream of particles. The poster's infinite redshift idea would probably treat light as a wave instead of as a stream of particles. Thanks to quantum mechanics, both views are valid.
Does this
The sims have noticed the garbage collectors and will soon start correlating disrepencies they cause with the simulated physics of the simulation. Once they realize that they're just a computer simulation, they always commit mass suicide. Oh well. Time to reset the simulation and start a fresh run...
I'm trying to teach myself to set people on fire with my mind... Is it hot in here?
When a star is formed, mass comes together and starts hydrogen fusion. As the fuel gets burned up, the light pressure/heat is decreased and it cools and becomes more compact. It can stop at this stage, or go on to burn helium, (which requires more mass and pressure) if the right amount of mass is present, the gravitational pressure will squeeze the atoms into one big mass of neutrons. If even greater, the neutrons will be squeezed down into something and the mass will collaspe to become a black hole.
A black hole is created when the gravitational force is increased to the point that light can not escape from the interior of the object. We don't care about the size of the mass at this point, it is the size of the radius of no escape.
As you get farther from an object its gravitational effect is reduced. based on the mass and assuming the object does not spin, the size is directly related to the amount of mass. This distance is known as the event horizon.
If an object is nearby, it is pulled toward the black hole. If it is going directly toward the BH it will cross the horizon and be effectively lost. except they add to the gravitation of the object as a whole. If it is close but moving at an angle, it is accelerated past the object, torn apart, squeezed in next to other objects, and heated till it emits X-Rays. This loss of energy may be enough to drop it into the BH. If it is far enough away the object falls into a stable orbit.
Black holes generally grow in size. In a pure vaccume they can decay by the capture of 1/2 of virtual partical pairs. This happens at an increasing speed as the BH gets smaller.
I belive that particles falling into a black hole will cross the last bit of the boundry and avoid the general relativity problems by one of two methods. Quantum tunneling, and sitting at the border long enough for the event horizon to grow past them.
we can know very little about the inside of a BH because we can not observe then up close. Because they have been detected we do know that gravity can still exist inside them and the matter can have an effect still. (until they were detected I was betting that they would eliminate themselves as the gravity {space curvature} would not be able to escape)
the size of a black hole can be estimated by three means that I am aware of. 1} stuff rotating around it (dopplar shifts and such). 2} Amount of stuff being taken in (not in this case) 3) rate of change method. *if an object has consistant changes that occur in a short period of time, that time can not be less than the time it takes light to cross the object*. (this is my guess as to the tool being used here)
Despite all this I belive that it is possible to conduct some research into the interior structure of a black hole. {you must be a member of an advanced space traveling civilization of course}. just send two black holes at each other at various angles. momentum should be conserved. do they go through each other if they bump head on? What if they just touch? Send small black holes at a larger one and probe to determine the size of the nucleus just like Rutherford did with atoms. *The atom was unfathomable and unbrakeable until people started doing nasty things to it*
There, that will give them something to fight about for a while ;-)
I want a spell checker in slash dot :-(
-leoglas
i've looked at love from both sides now. from win and lose, and still somehow...
Ok, I suppose a lot of good questions offer more than a lot of poorly researched replies to the original article.. So here's to being productive!
Let me know if i am correct: Why is it that black holes cannot be detected? Is it because any light that would otherwise escape indicating its presence is consumed?
Also: What are some good books on black holes that one of a mind uneducated as far as black holes are concerned might be able to read wiht little trouble?
Ummm, am I mistaken in remembering that a black hole has infitine mass?
Also, the article says ~50k * Solar mass, which is definitely finite.
All three stars are approximately 4.2 (? can't remember that tenths digit) light years away with PC being a fraction of a light year closer (for now, anyway:)
I want to go there (Alhpa Centauri)
Bill - aka taniwha
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Bill - aka taniwha
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Leave others their otherness. -- Aratak
IIRC correctly, black holes instead have infinite density. This is not a contradiction, because the actual size of a black hole is zero (not the size of the event horizon, but the size of the actual black hole).
As a matter of interest, you referred to the concept of a "value of infinite that is greater than other black holes". This has little to do with black holes, but it's worth noting that in number theory, there are indeed infinities that are bigger than other infinities. The proof of this is fairly easy to understand - if you're interested, try this page for a very accessible explanation.
Just so ya know. ;-)
Re: formation. When a star is in the happy, go-lucky stages of its life (the Main Sequence, when its burning Hydrogen into Helium in its core), and even a little later, its structure is set largely by the balance of gravity against ordinary gas pressure. (Take the term "ordinary" loosely here.) Later on, as material in the core of the star becomes very tightly packed, etc, that core becomes electron degenerate -- what's holding it up is the tendency of electrons to dislike rather intensely being crammed next to other electrons. (Again, I'm grossly simplifying things here, but what the hell.) This, in turn, leads to all kinds of interesting things -- for one, the conductivity of electron-degenerate matter is extremely high, so it tends to be largely isothermal; for another, degenerate matter is just plain weird : when you pile more mass onto the degenerate core, the damn thing gets smaller! So you see the normal cycle of compression-expansion is screwed up, and strange things can happen. The degeneracy will actually be broken multiple times in the life of the star, as the core eventually reaches its ignition temperate (in massive enough stars : and remember, because its isothermal, the whole thing reaches the ignition temp. more or less at the same time -- which is why you get the so-called "Helium flash" or "carbon flash").
I've veering wildly off-topic here, so back to the point: eventually, if the star is massive enough, even electron degeneracy pressure isn't enough to hold up the star against the crushing pull of gravity. The core collapses -- the electrons fuse with protons to form a big soup of neutrons, which can exert an even more impressive form of degeneracy pressure. (The core-collapse process, as you might imagine, is pretty dramatic: remember that this is an awful lot of mass we're talking about here. There is a rebound off the neutron-degenerate core, plus an outgoing flood of neutrinos which were produced in the p-e fusion into neutrons -- a truly stupendous amount of energy is released, and we call it a Supernova.) And (you can probably see this coming) if the remnant core is massive enough, even neutron degeneracy pressure isn't enough. But we know of no force in the universe that can stop the collapse after that : the object collapses indefinitely, to a singularity.
But the Black Hole, it should be mentioned, comes into being long before all the mass is concentrated in a single point : a BH can be said to exist the moment an event horizon exists -- that is, the instant the density of matter in a region is so great that the escape velocity from that region is greater than the speed of light.
God, that was a long answer to a short question. To top it all off, the supermassive BHs in the cores of galaxies may be totally different beasts -- nobody is entirely sure how they form, though certainly there is a long process of merging and growing before they attain their current (billion-M_sun) masses.
2.3.4 : I don't really have the energy to answer these very completely anymore. :-) But very "briefly." 2: black holes don't suck, any more than normal matter does. If our sun were magically replaced by a black hole, our orbit wouldn't change one bit. (Of course, we wouldn't have too long to appreciate that fact, since we would miss rather dearly the lack of sunlight.) A BH is "different" from a normal object, attraction-wise, only once you get pretty darn close to the thing. So yes, they will eventually stop growing. 3: people use "size" sloppily, but I usually mean the radius of the event horizon. This is really the only definable radius for a BH; it is related to the mass by a well-known formula. Some people also use "size" interchangeably with "mass" -- there are certainly more or less massive BHs. 4: no. :-) but you're actually hitting on some real points here -- to an outside observer, and supposing certain other things, it would like someone falling into a BH was taking an infinite amount of time to do so; in fact the Russian term for BHs was, IIRC, "frozen star," for precisely this reason. read Kip Thorne's book, called -- I think -- "Black Holes and Time Warps," for a good discussion of this sort of thing.
Hope this helps.
Many low luminosity galaxies, although showing evidence of having very massive black holes at their center, appear less bright than expected given the calculated size of their black holes. This has been explained by models which assume that the black holes in question are "underfed", i.e. that there's no longer enough matter close enough to the holes to create larger amounts of radiation.
However, the galaxy described in this paper, NGC4395, is an exception to this scenario, which is why it is interesting. Although it is of similar low luminosity to the galaxies described above, according to this paper, it shows evidence of containing a much smaller black hole than other low-luminosity galaxies. This smaller hole is from 10,000 to 100,000 solar masses, which is small for a galactic-core black hole.
The paper concludes that NGC4395 behaves more like a brighter galaxy with a larger hole, but because its hole is small, it appears dimmer. Attempting to apply the massive-underfed-hole model to this galaxy, based on it having low luminosity, gives incorrect results; instead, the model that applies is that of brighter galaxies with larger holes, except that in this case, the hole is smaller and thus the galaxy dimmer.
The space.com article actually did manage to say something along these lines, but you have to completely ignore the first half of the article, which is confused nonsense, and read the following paragraphs:
Until now, scientists had speculated that black holes residing in galaxies with dim cores - such as NGC 4395 - were either too old or too small to quickly eat up lots of material, as more massive black holes do on a regular basis. But now it seems that "mid-mass" black holes (a new nickname for the smallest type of supermassive black holes) may simply be more efficient matter-eaters.
"We now see that the nuclear source in NGC 4395 is a scaled-down version of black holes found in the most luminous of galaxies," said, Andrew Fabian, another Institute of Astronomy researcher who worked on the discovery. "Everything is the same, only it is smaller."
As a result, some astronomers now think that the total output of X-rays from accreting matter may therefore be more a product of how massive the black hole is, rather than of the luminosity of the region surrounding the black hole, as it once was thought.
Hawking and Berkenstein came up with this concept in the 70s. Since Hawking radiation implies that black holes have a temperature it follows that they have an entropy as well, and the relationship is S=A/4h, where A is the surface area in appropriate units.
This theory has recently been proved using string theory. Since entropy has its basis in the number of available quantum states of a system, Strominger and Vafa showed this relationship to be true by counting the degeneracy of configurations for strings and D-branes corresponding to black holes in string theory. This is a real result for string theory, since up till then the theory only had a semiclassical derivation.
For more information, see here for more information on the superstring proof or here for the semiclassical derivation.
Yes, I think they determined its mass (about 50.000 sun masses) by observing its effect on the galaxy it sits in. I don't think it has a larger gravitational pull than other black holes of the same mass - if it had, it would look like a larger supermassive black hole of several million sun masses. If I understood the article right, this BH gobbles up mass at the same rate as a black hole of millions of sun masses. Matter falling into a BH is accelerated by the gravitational pull to tremendous speeds and is heated up to very high temperatures. You cannot see the black hole itself, but matter falling into it is very visible - especially in the x-ray spectrum.
I think, this particualar black hole swallows so much matter, because there is enough matter there. Most supermassive black holes probably already have consumed most matter in their vincinity.
Stefan
I by even further means would be an astrophysicist, but if a blackhole had infinite mass let's say.
;-).
Lets not say that, because they don't have infinite mass
The article even says 50k * solar mass.
There'd be an enormous observable doppler effect. Two blackholes rotating around each other (besides being improbable) would have to revolve at an enormous speed in order to avoid collapsing from their enormous gravitational pulls.
And why are you mentioning special relativity? Special relativity is all about not taking gravity into account, and blackholes are all about gravity.