I can understand a gamma ray burst when two neutron stars merge, but why would two merging black holes result in a burster? I'd think that the energy of the merge would be trapped inside their event horizons. Could it be from the merging accretion disks? Thanks
Welcome I too have wondered about these things, but am totally unqualified to provide any answers, however here are some of my speculations: I do not understand the time scales as time itself is very changed in high gravity fields. Yet surely at some stage before the complete merger, even before their separate "no escape" boundaries merge into one, there must be two co-rotating masses, with lot of gravity waves emitted, etc. Already I am lost, as we have time passing at different rate around a quasi dumbbell. What could that look like? Does the middle of the dumbbell, where the gravitational dilation of time is less, rotate more rapidly than the ends? Etc. Does the radiant energy of their mutual collapse "leak out" from this "middle region" (both because time is more at it normal "fast rate" there and also because "escape" nearer either mass is already impossible)? It is all so complex and above me that I gave up and tried to imagine (lacking the math and physics skill to do anything else) what it must be like to form a single black hole during the collapse of a massive star. The first thing I concluded about this lesser problem is that almost every thing that has been published on it, is surely nonsense because it assumes (In all cases think) a symmetric collapse, althouhg not a spherically symetric one. As I do know a little something about the plasma and fusion conditions in the core of a star, I think such symmetry highly improbable for the following easy to understand reason: The rate of fusion is a very strong function of the temperature as it is only a very small (much less than 0.001% of the highly-charged (as they are fully ionized) atoms that exist to make iron out of which will be on essentially direct head-on collisions with enough kinetic energy to over come the electric repulsion forces and even come close the separation region where the strong nuclear forces and complete the fusion. That is, if any small part of the stellar core is slightly hotter than the exact center, it will rapidly be come hotter still as it will have a larger fusion rate. the heat released will of course cause the density in that region to drop but the fusion rate depends only on the square of the density and the exponential dependency upon the temperature is more important. SUMMARY of this point: There is an instability mechanism that is very likely to make some part of the stellar core, near the center, "burn" its fuel into iron and then collapse before the exact center does. SUMMARY OF MAIN POINT: Analytical models that assume symmetery of black hole formation by large stars are wrong. What probably happens is that a smaller black hole, not at exactly the stellar core center forms and the gravitational energy released by its formation blasts the main body of the star into space, but on some time scale, (10s of thousands of years or more?) much of this expelled mass falls back into the mutual gravitation center, which may or may not, (depending on how asymmetric the first blast was) contain the initially formed black hole. The in-falling mass will be more mixed than when it was in shells of the original star, each perhaps at some different stage in the sequence of fusion processes possible prior to iron formation. Thus, I believe that it more probable that EACH of the first generation large star (typically 50 to 350 solar masses) formed several, if not "many" black holes before they "went dark" forever. As these big stars run thru their life cycles much more rapidly than our sun, there were several generations of them prior to the formation of the sun. If true that each of the several generations now all dark, formed many black holes of a few solar masses, then there may be more more small black hole, often in gravitationally bound pairs now, than not only all the current stars, but more than all the stars that have ever existed. These types of thoughts, the fact that we would not know it was coming (does not reflect sunlight) form the basis for the “cosmic horror story” in my book Dark Visitor which also uses the fact that something in the late 1920 perturbed planet Neptune. This perturbation, observed by many astronomers, lead to the search, which found Pluto. (Actually by hard work and chance. - Although Pluto was thought to be the cause until approximately 1950 it now is known that it was not. Pre-1950 Pluto was thought to be several times more massive than Earth as that much mass is required in Pluto's orbit to make the observed perturbation, but it is now known that Pluto is smaller than the moon. The cause of Neptune's perturbation is unknown and now many argue that it was just "measurement errors" or "poor math" by many different astronomers, but I think it could have been the first of a gravitationally bound pair of small black holes, and built the Dark Visitor story on this assumption. The book is intended to scare some people, not currently interested in physics, to become so. - A recruiting tool if you want to think of it that way, as I do. More details, list of physic in book etc, at site under my name and also instructions as to how you can read book for free.
http://www.space.com/scienceastronomy/astronomy/blackhole_merges_020208.html never mind, found the answer, its the accretion disk of one black hole being eaten by the other hole judt before they merge.
