Broad-band X-ray spectra of anomalous X-ray pulsars and soft $\gamma$-ray repeaters: pulsars in a weak-accretion regime ?

Abstract

We present the results from the analysis of the broad-band X-ray spectra of 5 Anomalous X-ray Pulsars (AXPs) and Soft $\gamma$-ray Repeaters (SGRs). We fit their Suzaku and INTEGRAL spectra with models appropriate for the X-ray emission from the accretion flow onto a pulsar. We find that their X-ray spectra can be well described with this model. In particular we find that: (a) the radius of the accretion column is $\sim 150-350$ m resulting in a transverse optical depth of $\sim 1$; (b) the vertical Thompson optical depth is $\approx 50-400$, and (c) their luminosity translates in accretion rates $\approx 10^{15}\mathrm{g}{\mathrm{s}}^{-1}$. These results are in good agreement with the predictions from the fall-back disk model, providing further support in the interpretation of AXPs and SGRs as accreting pulsars.

Accepted for publication in MNRAS, 10 pages, 2 figures

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Cited by in corpus (5)

• Heat blanketing envelopes of neutron stars
• Long-term evolution of anomalous X-ray pulsars and soft gamma repeaters
• A NuSTAR study of the 55 ks hard X-ray pulse-phase modulation in the magnetar 4U 0142+61
• A magnetic white-dwarf accretion model for the anomalous X-ray pulsar 4U 0142+61
• An observational argument against accretion in magnetars