Variable gamma-ray emission from the Be/X-ray transient A0535+26?
Instituto Argentino de Radioastronomía, C.C.5, (1894) Villa Elisa, Buenos Aires, Argentina
Corresponding author: G. E. Romero, firstname.lastname@example.org
Accepted: 11 July 2001
We present a study of the unidentified gamma-ray source 3EG J0542+2610. This source is spatially superposed on the supernova remnant G180.0-1.7, but its time variability makes a physical link unlikely. We have searched in the EGRET location error box for compact radio sources that could be the low energy counterpart of the gamma-ray source. Although 29 point-like radio sources were detected and measured, none of them is strong enough to be considered the counterpart of a background gamma-ray emitting AGN. We suggest that the only object within the 95% error box capable of producing the required gamma-ray flux is the X-ray transient A0535+26. We show that this Be/accreting pulsar can produce variable hadronic gamma-ray emission through the mechanism originally proposed by Cheng & Ruderman (1989), where a proton beam accelerated in a magnetospheric electrostatic gap impacts the transient accretion disk.
Key words: X-rays: stars / gamma-rays: theory / radio continuum: galaxies / stars: individual: A0535+26 / stars: neutron
© ESO, 2001