In article <1radsr$att@access.digex.net>, prb@access.digex.com (Pat) writes: >   What  evidence  indicates that Gamma Ray bursters are very far away? >  > Given the enormous  power,  i was just wondering,  what if they are > quantum  black holes or something  like that  fairly close by? >  > Why would they have to be at  galactic ranges?    >  > my own pet theory is that it's  Flying saucers  entering > hyperspace :-) >  > but the reason i am asking is that most everyone assumes  that they > are  colliding nuetron stars  or  spinning black holes,  i just wondered > if any mechanism could exist  and place them  closer in. >  > pat           Well, lets see....I took a class on this last fall, and I have no notes so I'll try to wing it...           Here's how I understand it. Remember from stellar evolution that  black holes and neutron stars(pulsars) are formed from high mass stars, M(star)=1.4M(sun).  High mass stars live fast and burn hard, taking appoximately 10^5-10^7 years before going nova, or supernova.  In this time, they don't live long enough to get perturbed out of the galactic plane, so any of these (if assumed to be the sources of GRB's) will be in the plane of the galaxy.           Then we take the catalog of bursts that have been recieved from the various satellites around the solar system, (Pioneer Venus has one, either Pion. 10 or 11, GINGA, and of course BATSE) and we do distribution tests on our catalog.  These tests all  show, that the bursts have an isotropic distribution(evenly spread out in a radial direction), and they show signs of homogeneity, i.e. they do not clump in any one direction.  So, unless we are sampling the area inside the disk of the galaxy, we are sampling the UNIVERSE. Not cool, if you want to figure out what the hell caused these things.  Now, I suppose you are saying, "Well, we stil only may be sampling from inside the disk."  Well, not necessarily.  Remember, we have what is more or less an interplanetary network of burst detectors with a baseline that goes waaaay out to beyond Pluto(pioneer 11), so we should be able, with all of our detectors de tect some sort of difference in angle from satellite to satellite.  Here's an  analogy:  You see a plane overhead.  You measure the angle of the plane from the origin of your arbitrary coordinate system.  One of your friends a mile away sees the same plane, and measures the angle from the zero point of his arbitrary system, which is the same as yours.  The two angles are different, and you should be able to triangulate the position of your burst, and maybe find a source.  To my knowledge, no one has been able to do this.           I should throw in why halo, and corona models don't work, also.  As I said before, looking at the possible astrophysics of the bursts, (short timescales, high energy) black holes, and pulsars exhibit much of this type of behavior.  If this is the case, as I said before, these stars seem to be bound to the disk of the galaxy, especially the most energetic of the these sources. When you look at a simulated model, where the bursts are confined to the disk, but you sample out to large distances, say 750 mpc, you should definitely see not only an anisotropy towards you in all direction, but a clumping of sources  in the direction of the  galactic center.  As I said before, there is none of these characteristics.