Letter to the Editor
XMM-Newton observations of PSR B1957+20
Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany e-mail: firstname.lastname@example.org
Accepted: 9 January 2007
We report on XMM-Newton observations of the “Black Widow pulsar”, PSR B1957+20. The pulsar's X-ray emission is non-thermal and best modeled with a single powerlaw spectrum of photon index . No coherent X-ray pulsations at the pulsar's spin-period could be detected, though a strong binary-phase dependence of the X-ray flux is observed for the first time. The data suggest that the majority of the pulsar's X-radiation is emitted from a small part of the binary orbit only. We identified this part as being near to where the radio eclipse takes place. This could mean that the X-rays from PSR B1957+20 are mostly due to intra-shock emission which is strongest when the pulsar wind interacts with the ablated material from the companion star.
Key words: pulsars: individual: PSR B1957+20 / stars: neutron / X-rays: stars / binaries: eclipsing
© ESO, 2007