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

GÖĞÜŞ E., Baring M. G., Kouveliotou C., GÜVER T., Lin L., Roberts O. J., ...More

ASTROPHYSICAL JOURNAL LETTERS, vol.905, no.2, 2020 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 905 Issue: 2
  • Publication Date: 2020
  • Doi Number: 10.3847/2041-8213/abcfc8
  • Journal Name: ASTROPHYSICAL JOURNAL LETTERS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Aerospace Database, INSPEC
  • Keywords: Magnetars, Neutron stars, Soft gamma-ray repeaters, RESONANT CYCLOTRON SCATTERING, MAGNETIZED NEUTRON-STARS, PHOTON IMAGING CAMERA, RAY-EMISSION, XMM-NEWTON, FIELD, ABSORPTION
  • Istanbul University Affiliated: Yes

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 2020 April 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 x 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 nondipolar. The spectral models indicate that surface field strengths in somewhat localized regions substantially exceed the polar value of 4.4 x 10(14) G inferred from a spin-down torque associated with a rotating magnetic dipole.