Consequences of Interstellar Absorption for Models of Anomalous X-ray Pulsars

Abstract

We examine properties of thermal radiation emitted by strongly magnetized neutron stars (NSs). In particular, we show that the pulsation amplitudes of the energy-integrated flux are an increasing function of the absorption column density to the source. This is especially important for the interpretation of the Anomalous $X$-ray Pulsars (AXPs) as cooling neutron stars with high magnetic fields. We show that the high-pulsation amplitudes observed in these objects are consistent with cooling models, if the large amount of absorption to these sources is taken into account. We also show that cooling models imply inferred radii of the emitting regions on the order of $\sim 5-6$ times smaller than the actual NS radii, again in agreement with observations.

6 pages, 2 figures, ApJL in press

References in corpus (4)

• An Accretion Model for Anomalous X-Ray Pulsars
• Emission Spectra of Fallback Disks Around Young Neutron Stars
• The Compact Central Object in Cas A: A Neutron Star with Hot Polar Caps or a Black Hole?
• Impacts of the Detection of Cassiopeia A Point Source

Cited by in corpus (8)

• Magnetars vs. high magnetic field pulsars: a theoretical interpretation of the apparent dichotomy
• Anomalous X-ray Pulsars and Soft gamma-ray Repeaters: Spectral Fits and the Magnetar Model
• Constraints on Thermal Emission Models of Anomalous X-ray Pulsars
• Emission geometry, radiation pattern, and magnetic topology of the magnetar XTE J1810-197 in its quiescent state
• Spectral features in isolated neutron stars induced by inhomogeneous surface temperatures
• Disks irradiated by beamed radiation from compact objects
• The imprint of the crustal magnetic field on the thermal spectra and pulse profiles of isolated neutron stars
• X-ray emission from middle-aged pulsars