Neutrino production from accreting x-ray pulsars

Abstract

There exist electrostatic acceleration regions (accelerator gaps) above the inner part of a Keplerian accretion disc of an x-ray pulsar which can accelerate positively charged particles (protons/ions) to extreme relativistic energies (>or=10 15 eV) towards the accretion disc. The subsequent hadronic collisions between such ultrarelativistic protons (ions) and the disc material can produce numerous secondary mesons whose decay generates a luminous neutrino flux. Although the neutrinos can directly escape from the collision regions without any energy loss, the disc magnetic field can modify the neutrino spectrum because their unstable charged parent particles can lose energy via synchrotron radiation. This can provide direct information on the structure of the accretion disc. In calculating the meson production rate, the authors have used an improved scaling violation model which has the effect of enhancing the neutrino production rate. It appears that a large fraction of the accretion power of x-ray pulsars ( approximately 10 37 erg s -1) could be carried away by the neutrino flux. It may be to detect these neutrino sources in future.