Phase-resolved NuSTAR spectra of magnetars and the coronal outflow model
Abstract
The coronal outflow model was recently proposed to explain the persistent hard X-ray emission from magnetars. In this model, hard X-rays are produced by a decelerating electron-positron flow in the closed magnetosphere. The flow decelerates as it radiates its energy away via resonant scattering of soft X-rays, then it reaches the top of the magnetic loop and annihilates there. We test the model against the NuSTAR observations of 1E 1841-045 and 1E 2259+586 and find that it successfully fits the observed phase-resolved spectra. We derive constraints on the angle between the rotational and magnetic axes of the neutron star, the object inclination to the line of sight, and the size of the active twisted region filled with the plasma flow. Using the fit of the hard X-ray component, we revisit the remaining soft X-ray component of the magnetar spectrum observed down to 0.5 keV with Swift XRT. We find that it can be explained by a modified two-temperature blackbody model. The hotter blackbody suggests a hot spot covering 1-10% of the neutron star surface. Such a hot spot is expected at the base of the coronal outflow, as some particles created in the e± discharge flow back to the star and bombard its surface. We also apply the coronal outflow model to earlier observations of two other magnetars 4U 0142+61 and 1RXS J1708-40 and compare them with 1E 1841-045 and 1E 2259+586.
- Publication:
-
40th COSPAR Scientific Assembly
- Pub Date:
- 2014
- Bibcode:
- 2014cosp...40E1166H