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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.
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"
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.
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 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
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?
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.
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.
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.