A magnetar strength surface magnetic field for the slowly spinning down SGR 0418+5729

Tolga Güver, Ersin Göǧüş, Feryal Ozel

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

The observed upper bound on the spin-down rate of the otherwise typical soft gamma-ray repeater SGR0418+5729 has challenged the interpretation of this source as a neutron star with ultrastrong magnetic fields. Current limits imply a dipole magnetic field strength of less than 7.5 × 1012G, which is significantly smaller than that of a typical SGR. Independent of the properties inferred from X-ray timing, the X-ray spectra of neutron stars allow a measurement of their magnetic field strengths because they are distorted from pure blackbodies due to the presence of a magnetic field a radiative equilibrium atmosphere. this paper, we model high signal-to-noise ratio XMM-Newton spectra of SGR0418+5729 to place constraints on the strength of the magnetic field at the surface of the neutron star. Our analysis shows that neutron star atmosphere models with moderate magnetic field strengths (1012-13G) cannot fit the X-ray spectra, whereas models with stronger magnetic fields are able to account for the observations. We find that the strength of the magnetic field at the surface is 1.0 × 1014G. This value, although lower than all of the other SGRs analysed to date, is still high enough to generate the observed X-ray bursts from the source. connection to the spin-down limits, it also implies a significantly non-dipolar structure of the magnetic field. We discuss the results of our spectral modelling and compare them with other SGRs.

Original languageEnglish (US)
Pages (from-to)2773-2778
Number of pages6
JournalMonthly Notices of the Royal Astronomical Society
Volume418
Issue number4
DOIs
StatePublished - Dec 2011

Fingerprint

magnetars
metal spinning
magnetic field
magnetic fields
neutron stars
field strength
x rays
atmospheres
repeaters
atmosphere
XMM-Newton telescope
signal-to-noise ratio
newton
bursts
signal to noise ratios
time measurement
gamma rays
dipoles

Keywords

  • Stars: magnetars
  • Stars: neutron
  • X-rays: individual: SGR0418+5729

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

A magnetar strength surface magnetic field for the slowly spinning down SGR 0418+5729. / Güver, Tolga; Göǧüş, Ersin; Ozel, Feryal.

In: Monthly Notices of the Royal Astronomical Society, Vol. 418, No. 4, 12.2011, p. 2773-2778.

Research output: Contribution to journalArticle

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