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Gamma Ray Bursts.


Perkil8r
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Following on from a very interesting lecture at the Long Eaton School Obs last week, I have become interested in GRB's, more specifically the short ones.


 


The long one's we understand are caused by larger mass stars going Supernova, but the short ones have not yet been positively decided upon in relation to what causes them. They appear to come from relatively nothing by comparison to the long ones, and almost always from young galaxies. One theory is that they are the result of Binary Neutron stars colliding at near the speed of light.


 


My theory, which is based on absolutely no proof what so ever, is that they could be the result of an event very similar to the birth of our known universe. Afterall, we believe that the universe was born from nowhere in an instantaneous event of enormous energy. Could these short duration GRB's be the tell tale signs of similar such events which don't quite get it right? In effect failed births of new universes.


 


Further reading: http://en.wikipedia.org/wiki/Gamma-ray_burst yes I know Wiki isn't always the most reliable source, but in this case seems to be pretty much as it was explained in the lecture.


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Interesting theory Mike, but I have to say i would go with collision of 2 neutron stars or neutron star with


black hole.  They have detected after glow now on short gamma ray bursts which would indicate the above.


 


Couple of links for you to have a look at.


 


http://phys.org/news6997.html


 


Also i we discussed gravity waves i think have been detected on these SGRB wihich would indicate the hypothesis


that a merger of neutron star and or black holes is favourite :)


 


Bit as we know..... things can change in cosmology


 


Sheila


Edited by Sheila
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The neutron star and black hole merger would be my favorite theory out of the two. But consider this, if that were the case, it would result in the neutron star disappearing into the point of singularity. If our theory on the birth of the known universe is indeed correct, and it was created from essentially "nothing", could it be that an incident like that of a neutron star joining the point of singularity would provide a big enough kick to the black hole to alter and create the "big bang"? 


 


The only issue I have with the neutron star and black hole theory is that nothing can escape the gravity of the black hole, not even light. Ergo the gamma rays would not be able to achieve escape velocity? Which again either points towards:


 


  1. It can't be a neutron star being pulled into a black hole.
  2. If it is a neutron star being pulled into a black hole, it might be changing the black hole in some way.
  3. It's something else.
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No Mike if a neutron star gets sucked into a black hole as i understand it the black hole gets bigger and rotates faster is all.


Inside the black hole there is (theorised) i singularity but our maths breaks down here so it is uknown.  The neutron star is not big enough to affect a black hole that much, they can effectively for want of a better word digest other black holes and they just become 'bigger'.  At the centre of an active galaxy there are supermassive black holes many times bigger than we are talking here.


 


The GRB, it is not true that it will not escape, as the jets would be formed on initial contact with the black hole and providing they are just outside the event horizon (like a blazar) would escape, maybe this is why they are so short lived????


 


IMHO this is still a workable theory and does not have any holes that i can find???  But then i am not a physicist :lol:


 


Sheila.


Edited by Sheila
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I was not implying that a single neutron star would set off some sort of collapse of the black hole, what I meant was that maybe the straw that breaks the camels back is a neutron star? It is not yet known what happens to a black hole over time but it has been suggested that they might turn inside out for want of a better description. If it gets to a tipping point, maybe a neutron star could get pulled in and tip it over that point, that's what I was trying (badly) to explain or suggest.


 


I also doubt the idea that a gamma ray burst could escape in the way you describe. As I understand it (which could well be that I understand it wrong) everything outside of the event horizon or Schwarzschild Radius remains in tact, as soon as it passes this point it effectively is already in the black hole, therefore outside of the Schwarzschild Radius light etc can still escape, but at a much slower rate due to the gravity of the black hole. Once it passes the Schwarzschild Radius no light can escape. Even at 1.5 x the Schwarzschild Radius light would be bound by the gravity of the black hole and would form an orbit rather than leaving it to head out into the universe. I see no way in that case how a GRB could be detectable if it was a result of a Neutron star being pulled in, unless it changes the state of the black hole in some way. As I say, not as a result of the first neutron star being pulled in, but the one that tips it over a certain point somehow.


 


I am using this lecture as my source of information http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit3/blackholes.html


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Mike did you look at the Blazars where light escapes when accreting material is spiralling into a black hole???  The energy of these bursts is phenomenal.


 


Also when a supernova collapses into a black hole


 


Also i noticed that the lectures (correct me if i am wrong) have only been updated to 2007?  Is this correct. It may be that further advances in detection and


data have moved on, i do not know.  Also the things i am talking about (supermassive black holes are a different animal to normal black holes) there


are even hypermassive ones.  I cant see how a small neutron star would be a tipping point for a small black hole ever.  The keep growing and growing


and looking at the size of these things there are too many SGRB for me to accept the hypothesis.  But as I said can all change with more data.


 


If you take a look at quasars too...


 


the jets are not from the the star/neutron star etc passing the event horizon they are because the object is shredded whilst approaching the horizon and high ebergy jets are generated


here.  Once the shredded material reaches the event horizon then obviously it cannot escape..  It is not like dropping a stone into water...the event is catastrophic before


event horizon breach occurs.


 


I may not be explaining this very clearly but i am trying :D


http://en.wikipedia.org/wiki/File:Artist%27s_rendering_ULAS_J1120%2B0641.jpg


 


http://www.nasa.gov/topics/universe/features/andromeda-xray.html


 


http://www.space.com/5285-powerful-black-hole-jet-explained.html


Edited by Sheila
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Here is how the jets occur. The fast spin of the black hole create magnetic and electromagnetic fields that cause magnetic/charged matter to experience vast forces, especially when the charged volume of the spinning black hole is significant. The poles of this magnetism. are the poles of the spin, and these forces are sufficient in size to counteract the force of gravity. Hence, the matter does not have to move rapidly (i.e. near or > c) from the center of the black hole, but does continually move outward at a sufficiently rapid pace that is sufficient to counteract gravity. Yes it is true that light, per se, cannot escape a black hole, but matter, which has other forces acting on it besides gravity, can have a net positive acceleration (i.e. away from the black hole) without having to move faster than c. It simply moves at high speed (e.g. .05c) away from the center of the black hole due to the magnetic forces acting on it.

Read more at: http://phys.org/news/2012-01-black-hole-jets.html#jCp

 

this may help too mike :)

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Hmmm.... my theory just fell apart, in part. I still believe we may one day find evidence that a collapsing or dying black hole creates the circumstances which led to the birth of the known universe. That is probably a different topic though, albeit related to what I was originally thinking.


 


Although the neutron star "falling" in to a black hole seems like the most likely theory, mine is still an exciting one :lol:


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I agree Mike and the more details come in over the years the more exciting it gets.


I am sure there will be some stuff that is discovered that floors some of the theories


and confirms others :D


 


Sheila


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Mike another weird one for black holes and GRB's


 


 







GLOBS of plasma spat out by black holes can trigger the brightest flashes of lightartx_video.gif in the universe.


Gamma-ray bursts are high-energy flares that mostly originate billions of light years away, making it hard to see how they are created. In November 2011,NASA's Fermi satellite saw a gamma-ray burst coming from the galaxy 4C +71.07, which sits about 10.5 billion light years away. The galaxy was also being watched by the Very Long Baseline Array, a radio telescope network that can see small features at a distance.


The supermassive black hole at the galaxy's centre is feeding on surrounding matter, causing it to fire high-speed jets of particles. The radio array showed that, around the same time as the flare, the black hole spat out a knot of plasma that travelled up the jet at near the speed of light.


Electrons in the knot probably collided with and energised light from a slower-moving part of the jet, producing the gamma rays, says Alan Marscher of Boston University, who presented the work at a recent astronomy meeting in California. It's still a mystery, though, what made the black hole erupt.


 


 




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That's very interesting as in theory this is supposed to be impossible due to black holes having infinitive density and gravity. This does explain GRB's seeming to come from "nothing" since we can't "see" the black hole, only the evidence that one exists due to it's mass. Maybe this is evidence which will one day turn out to be to do with what I am trying to get to, ie a black hole becoming unstable for some reason?


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maybe, you would think there is a max size for one before it becomes unstable, but as yet no on seems to know.  perhaps we actually do not want to find


out if its near us :wacko:


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