re gamma ray bursters where are they i feel compelled to complain the statement that recent observations rule out merging neutron stars as sources of gamma ray bursts is utterly false even though it is popular enough to make it to batse press releases the idea behind the statement is as follows if you smack two neutron stars together or have a neutron star be gobbled up by a black hole a lot of energy is released enough for a gamma ray burst at a cosmological distance but so the reasoning continues this energy is released below a lot of matter so the radiation becomes thermalized and you expect to see roughly a blackbody spectrum the observed spectra are strongly non thermal so this model must be wrong as so often the fault lies with the imagination of the person who was trying to prove the model wrong rather than with the model it may be that the initial energy release is not seen as a gamma ray burst but the fireball of energy and matter that is created may spew out a relativistic flow when this slams into the surrounding medium a strong flux of non thermal gamma rays results which may carry off a substantial fraction of the initial total energy all this is not my idea it is in a series of papers by martin rees peter meszaros sorry for the missing accents and co workers it is certainly not a complete model but it may well be the best one around summing over all proposed distance scales an alternative proposal for what creates the initial fireball by the way is the so called failed supernovae scenario by stan woosley in which a very massive star at the end of its life collapses to a black hole if the stellar core was rotating part of the infalling matter will be temporarily halted because it is supported by centrifugal force and form a very dense neutron torus that accretes onto the black hole this beast may spew out a jet along the rotation axis which again constitutes relativistic flow the rate of such events may be much higher than that of neutron star mergers but the flux may be more strongly beamed so that the net rate of bursts observed on earth stays the same between the two scenarios but the energy released per event can be a lot less in the failed supernova scenario on another note i do believe that the distance scale must ultimately be resolved via some classical astronomical method such as finding counterparts to the bursts at other wavelengths or finding a definitive signature of some known class of objects in the distribution of positions and fluxes theorists have historically not been too successfull in finding the distance of any object by proving that there is only one possible way in which the object can work and therefore it must be so and so ralph wijers
