Abstract
We argue that magnetars, neutron stars with strong magnetic fields, can be the powerhouses behind some gamma-ray bursts (GRBs), thanks to effects only possible in presence of high magnetic fields. The production of axions in supernova cores by pair anihilation e+e- -> a is possible in such intense magnetic fields. A fraction of the ~ 1053 erg of binding energy of the newly created neutron star escapes with this axion flux. However, axions in high magnetic fields decay through a -> e+e- with mean life τ ~ 10-4 s, therefore close to the magnetar, producing the relativistic shock with ~ 1051 erg ("fireball") and the GRB. At least one GRB was coincident with an "anomalous" supernova Ic, supporting this scenario.
