Timing and flux evolution of the galactic center magnetar SGR J1745-2900

Victoria M. Kaspi, Robert F. Archibald, Varun Bhalerao, François Dufour, Eric V. Gotthelf, Hongjun An, Matteo Bachetti, Andrei M. Beloborodov, Steven E. Boggs, Finn E. Christensen, William W. Craig, Brian W. Grefenstette, Charles J. Hailey, Fiona A. Harrison, Jamie A. Kennea, Chryssa Kouveliotou, Kristin K. Madsen, Kaya Mori, Craig B. Markwardt, Daniel SternJulia K. Vogel, William W. Zhang

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Abstract

We present the X-ray timing and spectral evolution of the Galactic Center magnetar SGR J1745-2900 for the first ∼4 months post-discovery using data obtained with the Nuclear Spectroscopic Telescope Array and Swift observatories. Our timing analysis reveals a large increase in the magnetar spin-down rate by a factor of 2.60 ± 0.07 over our data span. We further show that the change in spin evolution was likely coincident with a bright X-ray burst observed in 2013 June by Swift, and if so, there was no accompanying discontinuity in the frequency. We find that the source 3-10 keV flux has declined monotonically by a factor of ∼2 over an 80 day period post-outburst accompanied by a ∼20% decrease in the source's blackbody temperature, although there is evidence for both flux and kT having leveled off. We argue that the torque variations are likely to be magnetospheric in nature and will dominate over any dynamical signatures of orbital motion around Sgr A*.

Original languageEnglish (US)
Article number84
JournalAstrophysical Journal
Volume786
Issue number2
DOIs
StatePublished - May 10 2014

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

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    Kaspi, V. M., Archibald, R. F., Bhalerao, V., Dufour, F., Gotthelf, E. V., An, H., Bachetti, M., Beloborodov, A. M., Boggs, S. E., Christensen, F. E., Craig, W. W., Grefenstette, B. W., Hailey, C. J., Harrison, F. A., Kennea, J. A., Kouveliotou, C., Madsen, K. K., Mori, K., Markwardt, C. B., ... Zhang, W. W. (2014). Timing and flux evolution of the galactic center magnetar SGR J1745-2900. Astrophysical Journal, 786(2), [84]. https://doi.org/10.1088/0004-637X/786/2/84