DEEP NuSTAR and SWIFT MONITORING OBSERVATIONS of the MAGNETAR 1E 1841-045

Hongjun An, Robert F. Archibald, Romain Hascoët, Victoria M. Kaspi, Andrei M. Beloborodov, Anne M. Archibald, Andy Beardmore, Steven E. Boggs, Finn E. Christensen, William W. Craig, Niel Gehrels, Charles J. Hailey, Fiona A. Harrison, Jamie Kennea, Chryssa Kouveliotou, Daniel Stern, George Younes, William W. Zhang

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Abstract

We report on a 350 ks NuSTAR observation of the magnetar 1E 1841-045 taken in 2013 September. During the observation, NuSTAR detected six bursts of short duration, with T 90 ≲ 1 s. An elevated level of emission tail is detected after the brightest burst, persisting for ∼1 ks. The emission showed a power-law decay with a temporal index of 0.5 before returning to the persistent emission level. The long observation also provided detailed phase-resolved spectra of the persistent X-ray emission of the source. By comparing the persistent spectrum with that previously reported, we find that the source hard-band emission has been stable for over approximately 10 yr. The persistent hard-X-ray emission is well fitted by a coronal outflow model, where e ± pairs in the magnetosphere upscatter thermal X-rays. Our fit of phase-resolved spectra allowed us to estimate the angle between the rotational and magnetic dipole axes of the magnetar, , the twisted magnetic flux, 2.5 × 10 26 G cm 2 , and the power released in the twisted magnetosphere, L j = 6 × 10 36 erg s -1 . Assuming this model for the hard-X-ray spectrum, the soft-X-ray component is well fit by a two-blackbody model, with the hotter blackbody consistent with the footprint of the twisted magnetic field lines on the star. We also report on the 3 yr Swift monitoring observations obtained since 2011 July. The soft-X-ray spectrum remained stable during this period, and the timing behavior was noisy, with large timing residuals.

Original languageEnglish (US)
Article number93
JournalAstrophysical Journal
Volume807
Issue number1
DOIs
StatePublished - Jul 1 2015

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All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

An, H., Archibald, R. F., Hascoët, R., Kaspi, V. M., Beloborodov, A. M., Archibald, A. M., Beardmore, A., Boggs, S. E., Christensen, F. E., Craig, W. W., Gehrels, N., Hailey, C. J., Harrison, F. A., Kennea, J., Kouveliotou, C., Stern, D., Younes, G., & Zhang, W. W. (2015). DEEP NuSTAR and SWIFT MONITORING OBSERVATIONS of the MAGNETAR 1E 1841-045. Astrophysical Journal, 807(1), [93]. https://doi.org/10.1088/0004-637X/807/1/93