Gamma ray bursts via emission of axion-like particles

The Pseudo-Goldstone Boson (PGB) emission could provide a very efficient mechanism for the cosmic Gamma Ray Bursts (GRBs). The PGBs produced in the merger of two neutron stars (or neutron star and black hole) can decay into e+e− and photons at distances of hundreds or thousands km, where the baryon density is low. In this way, a huge energy (up to 1054 erg) can be deposited into an ultrarelativistic e+e− plasma, the fireball. For producing a successful GRBs, the PGB should have mass of order MeV, coupling to nucleons gaN∼10−6 and to electrons gae∼10−9. Neither present experimental data nor astrophysical arguments can exclude such an ultramassive axion-like PGB. Our mechanism could also explain the association of some GRBs with supernovae type Ib/c and help the supernova type II explosion.