GAMMA-RAY BURSTS FROM HALO NEUTRON STARS CROSSING DARK CLUSTERS

Abstract

Two classes of neutron stars may exist in the galactic halo: high velocity neutron stars originating from the disk and injected in the halo and neutron stars originating from globular clusters (via type II supernovae and/or accretion induced collapse of white dwarfs). Moreover, the halo dark matter is likely in the form of dark clusters made of Massive Astrophysical Compact Halo Objects (MACHOs) and cold molecular clouds, expected to be formed in the outer part of the galaxy. We suggest that halo neutron stars may emit gamma-ray bursts crossing dark clusters. This assumption allows us to explain all the observed properties of gamma-ray bursts (rate, isotropy, cumulative peak flux distribution), including the different spectral properties of the two classes of short and long bursts. Several methods to test this model, independently on observations of gamma-ray bursts, are discussed.