The X-ray evolution and geometry of the 2018 outburst of XTE J1810-197
Date Issued
2021
Author(s)
Borghese, A.
•
Rea, N.
•
Turolla, R.
•
•
Alford, J. A. J.
•
Gotthelf, E. V.
•
•
•
Zane, S.
•
Coti Zelati, F.
•
Perna, R.
•
Esposito, P.
•
•
Viganò, D.
•
•
Götz, D.
•
Ibrahim, A.
•
•
Pons, J.
•
Sathyaprakash, R.
Abstract
After 15 yr, in late 2018, the magnetar XTE J1810-197 underwent a second recorded X-ray outburst event and reactivated as a radio pulsar. We initiated an X-ray monitoring campaign to follow the timing and spectral evolution of the magnetar as its flux decays using Swift, XMM-Newton, NuSTAR, and NICER observations. During the year-long campaign, the magnetar reproduced similar behaviour to that found for the first outburst, with a factor of 2 change in its spin-down rate from ~7.2 × 10-12 to ~1.5 × 10-11 s s-1 after two months. Unique to this outburst, we confirm the peculiar energy-dependent phase shift of the pulse profile. Following the initial outburst, the spectrum of XTE J1810-197 is well modelled by multiple blackbody components corresponding to a pair of non-concentric, hot thermal caps surrounded by a cooler one, superposed to the colder star surface. We model the energy-dependent pulse profile to constrain the viewing and surface emission geometry and find that the overall geometry of XTE J1810-197 has likely evolved relative to that found for the 2003 event.
Volume
504
Issue
4
Start page
5244
Issn Identifier
0035-8711
Ads BibCode
2021MNRAS.504.5244B
Rights
open.access
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