Pulse frequency fluctuations of magnetars

Cerri-Serim D., Serim M. M., Sahiner S., Inam S. C., Baykal A.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, vol.485, no.1, pp.2-12, 2019 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 485 Issue: 1
  • Publication Date: 2019
  • Doi Number: 10.1093/mnras/sty3213
  • Journal Name: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.2-12
  • Keywords: stars: magnetars, stars: neutron, pulsars: general, XMM-NEWTON OBSERVATIONS, SOFT GAMMA-REPEATERS, MAGNETIZED NEUTRON-STARS, RED POWER SPECTRA, X-RAY-EMISSION, TIMING NOISE, GIANT FLARE, SGR 1806-20, FREE PRECESSION, OUTBURST
  • Middle East Technical University Affiliated: Yes

Abstract

Using RXTE, Chandra, XMM-Newton and Swift observations, we construct the power spectra and torque noise strengths of magnetars for the first time. For some of the sources, on time-scales of months to years, we measure strong red noise that might be a consequence of their outbursts. We compare the noise strengths of magnetars with those of radio pulsars by investigating the possible correlations of noise strength with spin-down rate, magnetic field and age. Using these correlations, we find that the noise strengths of magnetars obey similar trends as radio pulsars. However, we do not find any correlation between noise strength and X-ray luminosity, a correlation that has been seen in accretion-powered pulsars. Our findings suggest that the noise behaviour of magnetars resembles that of radio pulsars, but magnetars possess higher noise levels likely because of their stronger magnetic fields.