On Electrostatic Positron Acceleration In The Accretion Flow Onto Neutron Stars

Abstract

As first shown by Shvartsman (1970), a neutron star accreting close to the Eddington limit must acquire a positive charge in order for electrons and protons to move at the same speed. The resulting electrostatic field may contribute to accelerating positrons produced near the star surface in conjunction with the radiative force. We reconsider the balance between energy gains and losses, including inverse Compton (IC), bremsstrahlung and non--radiative scatterings. It is found that, even accounting for IC losses only, the maximum positron energy never exceeds $\approx 400$ keV. The electrostatic field alone may produce energies $\approx 50$ keV at most. We also show that Coulomb collisions and annihilation with accreting electrons severely limit the number of positrons that escape to infinity.

9 pages plus 3 postscript figures, to be published in ApJ

Cited by in corpus (5)

• Maximum Mass-Radius Ratios for Charged Compact General Relativistic Objects
• Black holes as antimatter factories
• Vacuum Breakdown near a Black Hole Charged by Hypercritical Accretion
• Radiative acceleration and transient, radiation-induced electric fields
• Conversion of protons to positrons by a black hole