We report new spectral and temporal observations of the magnetar 1E 1841 - 045 in the Kes 73 supernova remnant obtained with the Nuclear Spectroscopic Telescope Array ( NuSTAR ) .
Combined with new Swift and archival XMM-Newton and Chandra observations , the phase-averaged spectrum is well characterized by a blackbody plus double power-law model , in agreement with previous , multi-mission X-ray results .
However , we are unable to reproduce the spectral results reported using Suzaku observations .
The pulsed fraction of the source is found to increase with photon energy .
The measured rms pulsed fraction is \sim 12 % and \sim 17 % at \sim 20 keV and \sim 50 keV , respectively .
We detect a new feature in the 24–35 keV band pulse profile that is uniquely double-peaked .
This feature may be associated with a possible absorption or emission feature in the phase-resolved spectrum .
We fit the X-ray data using the recently developed electron-positron outflow model of Beloborodov ( 3 ) for the hard X-ray emission from magnetars .
This produces a satisfactory fit allowing a constraint on the angle between the rotation and magnetic axes of the neutron star of \sim 20 ^ { \circ } and on the angle between the rotation axis and line-of-sight of \sim 50 ^ { \circ } .
In this model , the soft X-ray component is inconsistent with a single blackbody ; adding a second blackbody or a power-law component fits the data .
The two-blackbody interpretation suggests a hot spot of temperature kT \approx 0.9 keV occupying \sim 1 % of the stellar surface .