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2018 X-Ray and Radio Outburst of Magnetar XTE J1810–197

Gotthelf, E. V. and Halpern, J. P. and Alford, J. A. J. and Mihara, T. and Negoro, H. and Kawai, N. and Dai, S. and Lower, M. E. and Johnston, S. and Bailes, M. and Osłowski, S. and Camilo, F. and Miyasaka, H. and Madsen, K. K. (2019) 2018 X-Ray and Radio Outburst of Magnetar XTE J1810–197. Astrophysical Journal Letters, 874 (2). Art. No. L25. ISSN 2041-8213.

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We present the earliest X-ray observations of the 2018 outburst of XTE J1810−197, the first outburst since its 2003 discovery as the prototypical transient and radio-emitting anomalous X-ray pulsar (AXP). The Monitor of All-sky X-ray Image (MAXI) detected XTE J1810−197 immediately after a November 20–26 visibility gap, contemporaneous with its reactivation as a radio pulsar, first observed on December 8. On December 13 the Nuclear Spectroscopic Telescope Array (NuSTAR) detected X-ray emission up to at least 30 keV, with a spectrum well-characterized by a blackbody plus power-law model with temperature kT = 0.74 ± 0.02 keV and photon index Γ = 4.4 ± 0.2 or by a two-blackbody model with kT = 0.59 ± 0.04 keV and kT = 1.0 ± 0.1 keV, both including an additional power-law component to account for emission above 10 keV, with Γ_h = −0.2 ± 1.5 and Γ_h = 1.5 ± 0.5, respectively. The latter index is consistent with hard X-ray flux reported for the nontransient magnetars. In the 2–10 keV bandpass, the absorbed flux is 2 × 10^(−10) erg s^(−1) cm^(−2), a factor of 2 greater than the maximum flux extrapolated for the 2003 outburst. The peak of the sinusoidal X-ray pulse lags the radio pulse by ≈0.13 cycles, consistent with their phase relationship during the 2003 outburst. This suggests a stable geometry in which radio emission originates on magnetic field lines containing currents that heat a spot on the neutron star surface. However, a measured energy-dependent phase shift of the pulsed X-rays suggests that all X-ray emitting regions are not precisely coaligned.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Gotthelf, E. V.0000-0003-3847-3957
Kawai, N.0000-0001-9656-0261
Lower, M. E.0000-0001-9208-0009
Bailes, M.0000-0003-3294-3081
Camilo, F.0000-0002-1873-3718
Miyasaka, H.0000-0002-8074-4186
Madsen, K. K.0000-0003-1252-4891
Additional Information:© 2019 The American Astronomical Society. Received 2019 February 21; revised 2019 March 14; accepted 2019 March 15; published 2019 April 2. The NuSTAR mission is a project led by the California Institute of Technology, managed by the Jet Propulsion Laboratory, and funded by the National Aeronautics and Space Administration. We thank the NuSTAR Director for timely approval of this observation of XTE J1810−197, and the NuSTAR Operations, Software, and Calibration teams for support with the execution and analysis of the observation. We thank the UTMOST team and the University of Sydney for maintaining the Molonglo Observatory. E.V.G. acknowledges NASA ADAP Grant NNX16AF30G. M.B. acknowledges ARC grant LF150100148. This research made use of the NuSTAR Data Analysis Software (NuSTARDAS) jointly developed by the ASI Science Data Center (ASDC, Italy) and the California Institute of Technology (USA). This research also made use of data and software provided by the High Energy Astrophysics Science Archive Research Center (HEASARC), which is a service of the Astrophysics Science Division at NASA/GSFC and the High Energy Astrophysics Division of the Smithsonian Astrophysical Observatory. We also acknowledge use of the Astronomer's Telegram (ATel) and the NASA Astrophysics Data Service (ADS).
Group:NuSTAR, Space Radiation Laboratory
Funding AgencyGrant Number
Australian Research CouncilLF150100148
Subject Keywords:pulsars: general – pulsars: individual (XTE J1810–197) – stars: neutron – X-rays: stars
Record Number:CaltechAUTHORS:20190402-112157216
Persistent URL:
Official Citation:E. V. Gotthelf et al 2019 ApJL 874 L25
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:94366
Deposited By: Tony Diaz
Deposited On:02 Apr 2019 18:31
Last Modified:02 Apr 2019 18:31

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