The Reanimation of Magnetar XTE J1810-197: A NuSTAR Observation of the 2018 X-ray Outburst
Abstract
We present the first X-ray observation of the 2018 outburst of themagnetar XTE J1810-197, 15 years after the 2003 discovery of this, thefirst known transient and radio anomalous X-ray pulsar (AXP). A 13December observation of XTE J1810-197 with the Nuclear SpectroscopicTelescope Array (NuSTAR) detected X-ray emission up to at least 30 keVwith a spectrum well-modeled by blackbody plus power-law components oftemperature kT = 0.72+/-0.02 keV and photon index Gamma = 4.15+/-0.20,similar to the results for the 2003 outburst. In the broad NuSTARenergy band, we find evidence of hard emission above 10 keV. Modeledas an additional power-law, its flat spectral slope is harder thanthat of most magnetars. In the 2-10 keV bandpass, the absorbed fluxis (2.12+/-0.07)E-10 erg/s/cm^2, is a factor of 2 greater than themaximum flux extrapolated for the 2003 outburst. Compared topre-outburst, the flux has increased by a factor of 360 in the 0.3-10keV band. We also present evidence of an energy dependent phase shiftof the pulsed signal, suggesting that the X-ray emission componentsare non-aligned at the current epoch. This may be transitory, as wefind no evidence for this at later epochs during the 2003 outburst.
- Publication:
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AAS/High Energy Astrophysics Division
- Pub Date:
- March 2019
- Bibcode:
- 2019HEAD...1711262G