daveb writes "There was some discussion back in September regarding the first pictures from the Chandra satillite obervatory. I thought you might be interested in this article about identifying the source of much "background" x-ray radiation. "
It is thought that quasars are early versions of galaxies where the formation gasses are being pulled into a central black hole ( billions of solar masses ) and shining tons of light. Then after awhile an equilibrium sets in and eventually spirals and other older type galaxys form. I often wondered what could have kicked this off.
This seems to be the answer. One of the things Hawkings theorized was that there could be primordal black holes created during the big bang. It is possible that trillions of these things existed and as such started the initial imbalance required to create structure as we see now in the visible part of our universe.
These objects are said in the article to be the oldest things ever observed. I would say just younger than the 2.7 degree kelvin background radiation marking the time when the universe was opaque.
These smaller primordal blackholes would collide and create the gravitational engines that galaxies would form around. Initially, they would suck in gas and burn like a quasar then eventually settle down and become boring old spirals like ours.
As things were far more compact at this time most of the primordals would be gone, but a few may have "slingshoted" from near misses and be cruising near light speed through the universe right now.
People are mostly looking for dark matter within galaxies. The biggest problem right now is that given the rate that galaxies are spinning, they should fly apart if the only mass in them is the stars we see (assuming that we're doing a good job of calculating the mass of stars).
IMVHO, the "dark matter" is mostly a bunch of sub-stars like Jupiter (these are known as the Massive Astrophysical Compact Halo Objects, or MACHO, a term which covers all big dark matter, like black holes and brown dwarfs), which would have to be about a hundred times more common than stars to explain it. I believe in small MACHOs because small stars are much more common than large stars; a lot of people like to believe that black holes are common, but if matter tended to group together that much you'd expect larger stars to be more common than smaller stars.
That's Hawkings radiation
by
coyote-san
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· Score: 4
That's Hawkings radiation, something which provides a mechanism for small black holes to "evaporate" over time. It's an exponential conversion of mass to energy, so you do *not* want to be near one at the final moments!
Hawkings radiation is interesting for a different reason. Some people had observed that black holes physics have a lot of similaries with thermodynamics. The mass of the black hole corresponds to entrophy, iirc. However there was some minor point where the behaviors differed, and Hawkings decided to explore the "impossible" case where black holes really did match thermodynamics. He eventually identified the quantum tunneling mechanism and all hell broke loose in the physics community. Hawkings radiation is now a classic example of a situation where important discovery was made by exploring something that first appears to be a mere coincidence.
As others have pointed out, the X-rays we're talking about here are due matter falling into the accretion disk.
-- For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
Re:Well that's very cool!
by
CaptainCarrot
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· Score: 4
I've always been an armchair theoretical physicist, and I think this is fascinating. But what does this do to the 3 degrees above zero theory that said the background radiation was a residue of the big bang? Sure doesn't sound like it now...
So what does this do to the "big bang" theory?
It's got nothing to do with that at all. The background radiation that is thought to be an echo of the Big Bang is microwave radiation equivalent to a black body at 3K. X-rays are much more energetic, and in the spectrum fall between ultraviolet light and gamma rays.
People seem to be misunderstanding the significance of this discovery. For almost 40 years, we've known about an "x-ray glow" with no apparent source that was scattered all over the sky. With Chandra, astronomers have been able to resolve discrete sources for the x-rays, so we now know exactly where they're coming from. I don't think the x-ray glow was ever as uniform as the background microwave radiation, which is identical in all directions with no apparent source.
-- And the brethren went away edified.
Re:X-rays can beat black hole gravity?
by
Constellation
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· Score: 4
Actually the X-rays don't escape the black hole. the current theory is (since we have never actually "seen" a black hole) is that as particles fall in to the balck hole, they enter a sort of, spiraling, decaying orbit (called the accretion disk). It is the friction between all of these particles in the accretion disk, that generates the x-rays. If the x-ray is released in the right direction it can escape being sucked into the black hole, since the accretion disk exists outside of the black holes event horizon.
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It is thought that quasars are early versions of galaxies where the formation gasses are being pulled into a central black hole ( billions of solar masses ) and shining tons of light. Then after awhile an equilibrium sets in and eventually spirals and other older type galaxys form. I often wondered what could have kicked this off.
This seems to be the answer. One of the things Hawkings theorized was that there could be primordal black holes created during the big bang. It is possible that trillions of these things existed and as such started the initial imbalance required to create structure as we see now in the visible part of our universe.
These objects are said in the article to be the oldest things ever observed. I would say just younger than the 2.7 degree kelvin background radiation marking the time when the universe was opaque.
These smaller primordal blackholes would collide and create the gravitational engines that galaxies would form around. Initially, they would suck in gas and burn like a quasar then eventually settle down and become boring old spirals like ours.
As things were far more compact at this time most of the primordals would be gone, but a few may have "slingshoted" from near misses and be cruising near light speed through the universe right now.
And you though a big astroid would be bad!
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People are mostly looking for dark matter within galaxies. The biggest problem right now is that given the rate that galaxies are spinning, they should fly apart if the only mass in them is the stars we see (assuming that we're doing a good job of calculating the mass of stars).
IMVHO, the "dark matter" is mostly a bunch of sub-stars like Jupiter (these are known as the Massive Astrophysical Compact Halo Objects, or MACHO, a term which covers all big dark matter, like black holes and brown dwarfs), which would have to be about a hundred times more common than stars to explain it. I believe in small MACHOs because small stars are much more common than large stars; a lot of people like to believe that black holes are common, but if matter tended to group together that much you'd expect larger stars to be more common than smaller stars.
That's Hawkings radiation, something which provides a mechanism for small black holes to "evaporate" over time. It's an exponential conversion of mass to energy, so you do *not* want to be near one at the final moments!
Hawkings radiation is interesting for a different reason. Some people had observed that black holes physics have a lot of similaries with thermodynamics. The mass of the black hole corresponds to entrophy, iirc. However there was some minor point where the behaviors differed, and Hawkings decided to explore the "impossible" case where black holes really did match thermodynamics. He eventually identified the quantum tunneling mechanism and all hell broke loose in the physics community. Hawkings radiation is now a classic example of a situation where important discovery was made by exploring something that first appears to be a mere coincidence.
As others have pointed out, the X-rays we're talking about here are due matter falling into the accretion disk.
For every complex problem there is an answer that is clear, simple, and wrong. -- H L Mencken
People seem to be misunderstanding the significance of this discovery. For almost 40 years, we've known about an "x-ray glow" with no apparent source that was scattered all over the sky. With Chandra, astronomers have been able to resolve discrete sources for the x-rays, so we now know exactly where they're coming from. I don't think the x-ray glow was ever as uniform as the background microwave radiation, which is identical in all directions with no apparent source.
And the brethren went away edified.
Actually the X-rays don't escape the black hole. the current theory is (since we have never actually "seen" a black hole) is that as particles fall in to the balck hole, they enter a sort of, spiraling, decaying orbit (called the accretion disk). It is the friction between all of these particles in the accretion disk, that generates the x-rays. If the x-ray is released in the right direction it can escape being sucked into the black hole, since the accretion disk exists outside of the black holes event horizon.