Persistent Emission Properties of SGR J1935+2154 During Its 2020 Active Episode

Abstract

We present detailed spectral and temporal characteristics of the persistent X-ray emission of SGR J1935+2154 based on our XMM-Newton and Chandra observations taken in the aftermath of its April 2020 burst storm, during which hundreds of energetic X-ray bursts were emitted, including one associated with an extraordinary fast radio burst. We clearly detect the pulsed X-ray emission in the XMM-Newton data. An average spin-down rate of 1.6$\times$10${}^{-11}$ s s${}^{-1}$ is obtained using our spin period measurement combined with three earlier values reported from the same active episode. Our investigations of the XMM-Newton and Chandra spectra with a variety of phenomenological and physically-motivated models, concluded that the magnetic field topology of SGR J1935+2154 is most likely highly non-dipolar. The spectral models indicate that surface field strengths in somewhat localized regions substantially exceed the polar value of 4.4$\times$10${}^{14}$ G inferred from a spin-down torque associated with a rotating magnetic dipole.

Accepted for publication in the ApJ Letters

References in corpus (10)

• Corona of Magnetars
• INTEGRAL discovery of a burst with associated radio emission from the magnetar SGR 1935+2154
• Untwisting magnetospheres of neutron stars
• Resonant cyclotron scattering in magnetars' emission
• Radio continuum and polarization study of SNR G57.2+0.8 associated with magnetar SGR1935+2154
• The Magnetar Nature and the Outburst Mechanism of a Transient Anomalous X-ray Pulsar
• The Sleeping Monster: NuSTAR observations of SGR 1806-20, 11 years after the Giant Flare
• Physical Properties of the AXP 4U 0142+61 from X-ray Spectral Analysis
• Simultaneous magnetic polar cap heating during a flaring episode from the magnetar 1RXS J170849.0-400910
• X-ray Perspective of the Twisted Magnetospheres of Magnetars

Cited by in corpus (7)

• Discovery of the linear energy-dependence of the spectral lag of X-ray bursts from SGR J1935+2154
• The first 7 months of the 2020 X-ray outburst of the magnetar SGR J1935+2154
• Constraining mechanism associated with fast radio burst and glitch from SGR J1935
• Multipolar Electromagnetic Emission of Newborn Magnetar
• Retuning radio astronomy for axion dark matter with neutron stars
• About the observational check of the mechanism of gamma radiation in Soft Gamma Repeaters (SGR)
• A month of monitoring the new magnetar Swift J1555.2-5402 during an X-ray outburst