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Universe Teeming With Black Holes
Porfiry writes "For the first time, astronomers believe they have proof black holes of all sizes once ruled the universe. NASA's Chandra X-ray Observatory provided the deepest X-ray images ever recorded (a million-second exposure), and those pictures deliver a novel look at the past 12 billion years of black holes. Combining infrared and X-ray observations, the Penn State team found veils of dust and gas are common around young black holes. 'The discovery of this object, some 12 billion light years away, is key to understanding how dense clouds of gas form galaxies, with massive black holes at their centers,' said Colin Norman of Johns Hopkins University."
Black holes "evaporate" via a process known a Hawking radiation. Basically, it works as follows:
1) A particle/anti-particle pair forms just above the event horizon.
2) One of the particle gets sucked in, the other escapes.
The energy to form the particle pair comes from the black hole itself, so that escaping particle carries off some energy. And E=mc^2 so it's exactly the same as if it had carried off some mass from the black hole.
- Blah blah blah, missing scientist. Blah blah blah, atomic bomb. -
Why's it so surprising that there's tons of black holes out there?
I agree: it doesn't seem very surprising. But this leads us to the opposite question: Why's there so much non-black hole stuff out there? According to the article, black holes were much more active in the past. Why did the situation change?
How do black holes form? Normally when matter coalesces it rotates, forming a galaxy , cloud, solar system, etc. I believe the accepted theory on formation of black holes is that a massive star supernovas, exerting huge compression on it own core and collapsing the matter into a black hole which then consumes the rest of the star.
As there were presumably no old stars to supernova at the beginning of the universe, how did these form? Possibly they are remnants from the big bang or perhaps there were huge amounts of matter which collapsed quickly shortly after the big bang, although these should also leave microwave imprints.
It's also worth noting that black holes could solve the convex/concave universe problem. It's been postulated that there is "dark matter" we cannot see accounting for the rest of the mass of the universe. If there are lots of small black holes out there it could explain this. This could prove that the universe will eventually collapse back in on itself creating a new big bang, instead of expanding forever.
Now, can anyone tell me whether this is definitive proof of the existence of black holes, or could these signals be produced by any type of dense matter?
Even when that happens, though, the black hole still will emit x-rays and such, so it is still detectable.
If the black hole is wandering through the universe having eaten its host galaxy, it'd be damn hard to detect. Even if it's emitting Hawking radiation, this would in no way compare to the emissions of, eg, Cygnus X-1. 'Detectable' is the operative word, here; Chandra is looking back twelve billion years; it's not going to detect anything that isn't (wasn't?) truly spectacular. Sissy Hawking radiation would be damn hard to detect in our own galaxy, let alone one that died before the sun formed.
Two words: gravitational lensing...
Ok, imagine for a second that you're looking at a distant galaxy. Since matter bends light, you get an image of it from one angle. Now, suppose you look for galaxies at an angle just slightly different from the first angle. You see a galaxy. Upon inspection, it looks eerily like the first galaxy... in fact, neighboring galaxies seem to have 'clones' like the first galaxy too! What is going on?!?
What's happening is you're experiencing a 'lensing' effect by some matter that you can't see, allowing you to see one galaxy from many different angles. You plug the numbers into your computer model of the universe, try to figure out how much matter would produce said effect, (by laws of general relativity), and lo and behold, you get this figure for large amounts of invisible matter!
Now, what I'm interested in is how many galaxies have 'eaten' all their surrounding dust. If there was any dust, the black hole would compress it to unimaginable degrees as it drew said dust in, producing x-rays of incredible magnitude... some of the brightest/most energy-producing objects in the universe are thought to be such super-holes. So, either those billions of black holes have mostly 'evaporated', (see another poster's explanation of the process), or they have sucked up all nearby gasses/dust... this discovery is going to produce some interesting fodder for the cosmologists. (and no, a cosmologist doesn't worry about makeup, guys, and the modeling careers of universes. Well, maybe some of them do, but that's not their job ;)
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IANASRP- I am not a self-referential phrase
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IANASRP- I am not a self-referential phrase
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These black holes may have formed from large clumps of matter relatively soon after the big bang, or from very early, super-large, short-lived stars. They could then have grown by absorbing matter from their vicinities in the relatively dense universe of the time.
It seems unlikely that black holes make up much of the dark matter in the universe, although they could be a part. We know by looking at the way galaxies rotate and move, that most of the dark matter is in galaxies, but reasonably evenly distributed through them rather than collected at the center. If this was small black holes we'd notice their Hawking radiation. If it was bigger ones, we'd notice their gravity in various ways.
Finally the X-ray signatures could possibly be other small and very hot objects, but we don't know of anything that could be that small and that hot except matter falling into a black hole.
ESO has also issued a press release on this topic, which IMHO is better than the NASA press release (more facts, less marketspeak).
A star is basically a diffuse cloud of gas that collapses in on itself due to its own gravity right? Fine. Let's just consider the life cycles of stars then. A typical star, such as our sun, will 'live' about 10 billion years. Right now, and for the past 5 billion or so years it's been burning hydrogen, to make helium. This takes a fair amount of energy and in return releases quite a bit. Helium on the other hand releases much more, but also requires a great deal more pressure. When the hydrogen runs out, the sun will then ignite the helium burning phase and pretty much expand to somthing like the orbit of venus and make the earth look not unlike mercury. In a zone surrounding the helium burning core, hydrogen burning will still continue, but now the burning of helium provides most of the star's energy. And where this hydrogen burning phase lasted billions of years, the accumulated helium will last a few hundred million. But our sun is an unremarkable star. After it is done burning helium it will generate a small nova revealing its white hot core and, in time, a beautiful planitary nebula. Let's consider what might happen if we could add more gas to our sun.
With more gas, there would be more gravity, so there would be more pressure over a greater volume so hydrogen burning would be more prolific. Hmmmm, by adding more fuel, we're increasing the rate at which it is consumed. So our billions of years of hydrogen burning might be short a billion. So we'll reach the following phase of helium burning sooner, and it too will proceed more quickly. Now we might be able to go beyond helium burning, and burn carbon. In fact this is what the super large stars do. A star of great mass, like a red super giant might be up to 10 billion km in diameter and would not be unlike an onion with different zones of fusion. And this star would be at the end of a life that progressed very quickly. Some lasting only a hundred million years or so, 1/100th the life span of our sun. But what happens at the end of a stars life? It's the energy from the nuclear fusion that literally holds stars up. Without it they collapse. Some stars collapse on an iron core that is so large, that the pressure inside the core forces some electrons into the interiors of all the protons in the iron core of the star. This produces a super nova, but the core, now a vastly smaller ball of neutrons with a 1 km iron crust is what remains. Even neutrons have their limit. They cannot bear an infinite burden. If the core were to be about 2 to 3 times the mass of the sun, it would be so great as to exceed the ability of neutrons to resist gravitation. So a black hole would be born. At least that's the short course.
Check out Black Holes by Jean-Pierre Luminet from Cambridge University Press ISBN 0521409063.
--Jimmy has fancy plans; and pants to match.
Chandra has two instruments, ACIS (Advanced Camera for Imaging and Spectroscopy) and HRC (High Resolution Camera). Almost all results going to the general public are made with ACIS. ACIS allows simultanoeus imaging AND spectroscopy. HRC was intended for really high resolution spectroscopy OR imaging.
ACIS is working nominally, and the Chandra team deserves all the credit for this. However, you do not hear that much about HRC. Why is that?
This is well documented: Have a look at the Chandra User Manual . See section 7.8.2.
Quote: The anti-coincidence shield of the HRC-S is not working because of a timing error in the electronics. The error is not correctable. As a result the event rate is very high and exceeds the total telemetry rate limit. So, they can not tell particles from X-rays.
The same in plain english: We are detecting more background than our data transfer can handle. The instrument is f*ked due to a silly electronics design error. We are very sorry, but that is all we can do about it.
Multiple Big Bangs are allowed -- see Big Crunch. The trouble is, no information is preserved across the singularity, so you can't have structure -- not even singularities like black holes -- come out on the other side.
Now, in principle you might be able to have a big bang spontaneously occur in our universe, creating a subuniverse -- see Multiverse. Michael Turner has been a big proponent of this lately. However, if this occurred it would either destroy our universe by inflating a huge bubble in it (so points in spacetime that were previously close together would now be separated by billions of parsecs) or you wouldn't see it happen because the new subuniverse would be hidden behind an event horizon (masquerading as an ordinary black hole) and thereby NOT distorting our metric to hell.
Either way, you don't get an "overwriting" of our universe with a new one. Unless you have a false vacuum decay or something, which is an entirely different issue, and probably a load of crap.
Quantum mechanics: the dreams that stuff is made of.