Sj. Sturner et Cd. Dermer, ENERGY-DEPENDENT EFFECTS OF SCATTERING ATMOSPHERES ON X-RAY PULSAR PULSE PROFILES, Astronomy and astrophysics, 284(1), 1994, pp. 161-173
We propose that radiation-supported scattering atmospheres near accret
ing X-ray pulsars can explain energy-dependent features observed in th
e pulse profiles of 4U 1626-67, 4U 1538-52,4U 1907+09 and Vela X-1. Th
ese atmospheres provide a physical model for the phenomenological annu
lar emitting regions employed by Leahy to fit X-ray pulsar pulse profi
les. We examine the effects of the scattering atmospheres under the as
sumption that stable, optically thick atmospheres exist in a region wh
ere the optically thin resonant radiation force exceeds the force of g
ravity on ionized hydrogen. We predict that less complex pulse profile
s will be observed at higher photon energies because the scattering at
mospheres, which are supported by resonant Compton radiation pressure,
become transparent to photons with energies greater than the cyclotro
n energy at the neutron star surface.