NuSTAR OBSERVATIONS OF MAGNETAR 1E 1048.1-5937

作者：Yang, C.^*; Archibald, R. F.; Vogel, J. K.; An, H.; Kaspi, V. M.; Guillot, S.; Beloborodov, A. M.; Pivovaroff, M.

来源：Astrophysical Journal, 2016, 831(1): 80.

DOI：10.3847/0004-637X/831/1/80

• pulsars: general
• pulsars: individual (1E 1048.1)
• stars: magnetars
• stars: magnetic field
• stars: neutron
• X-rays: stars

We report on simultaneous Nuclear Spectroscopic Telescope Array (NuSTAR) and XMM-Newton observations of the magnetar 1E. 1048.1-5937, along with Rossi X-ray Timing Explorer (RXTE) data for the same source. The NuSTAR data provide a clear detection of this magnetar's persistent emission up to 20 keV. We detect a previously unreported small secondary peak in the average pulse profile in the 7-10 keV band, which grows to an amplitude comparable to that of the main peak in the 10-20 keV band. We show using RXTE data that this secondary peak is likely transient. We find that the pulsed fraction increases with energy from a value of similar to 0.55 at similar to 2. keV to a value of similar to 0.75 near 8. keV but shows evidence of decreasing at higher energies. After filtering out multiple bright X-ray bursts during the observation, we find that the phase-averaged spectrum from combined NuSTAR and XMM data is well described by an absorbed double blackbody plus power-law model, with no evidence for the spectral turn-up near similar to 10. keV as has been seen in some other magnetars. Our data allow us to rule out a spectral turn-up similar to those seen in magnetars 4U 0142+61 and 1E 2259+586 of Delta Gamma greater than or similar to 2, where Delta Gamma is the difference between the soft-band and hard-band photon indexes. The lack of spectral turn-up is consistent with what has been observed from an active subset of magnetars given previously reported trends suggesting that the degree of spectral turn-up is correlated with spin-down rate and/or spin-inferred magnetic field.

• 出版日期2016-11-1
• 单位北京理工大学