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 language | English (US) |
|---|---|
| Pages (from-to) | 2773-2778 |
| Number of pages | 6 |
| Journal | Monthly Notices of the Royal Astronomical Society |
| Volume | 418 |
| Issue number | 4 |
| DOIs | |
| State | Published - Dec 2011 |
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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 journal › Article
}
TY - JOUR
T1 - A magnetar strength surface magnetic field for the slowly spinning down SGR 0418+5729
AU - Güver, Tolga
AU - Göǧüş, Ersin
AU - Ozel, Feryal
PY - 2011/12
Y1 - 2011/12
N2 - 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.
AB - 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.
KW - Stars: magnetars
KW - Stars: neutron
KW - X-rays: individual: SGR0418+5729
UR - http://www.scopus.com/inward/record.url?scp=83155181853&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=83155181853&partnerID=8YFLogxK
U2 - 10.1111/j.1365-2966.2011.19677.x
DO - 10.1111/j.1365-2966.2011.19677.x
M3 - Article
AN - SCOPUS:83155181853
VL - 418
SP - 2773
EP - 2778
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
SN - 0035-8711
IS - 4
ER -