Our distorted view of magnetars: application of the resonant cyclotron scattering model

Rea, N.; Zane, S.; Lyutikov, Maxim; Turolla, R.

doi:10.1007/s10509-007-9306-1

Cited by 20 publications

(15 citation statements)

References 20 publications

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“…The soft X-ray emission from magnetar candidates (SGRs and AXPs) is usually interpreted within the twisted magnetosphere model as due to resonant cyclotron up-scattering of soft photons from the star surface onto charges flowing into the magnetosphere (Thompson et al 2002). Detailed calculations of resonant compton scattering (RCS) spectra have been recently performed (Lyutikov & Gavriil 2006;Fernández & Thompson 2007) and successfully applied to fit AXP spectra (Rea et al 2007). Quite interestingly, some of the model spectra presented by Fernández & Thompson (2007) exhibit a downward break in the tens of keV range.…”

Section: Discussionmentioning

confidence: 99%

SGR 1806-20 about two years after the giant flare:Suzaku,XMM-Newton andINTEGRAL observations

Esposito

Mereghetti

Tiengo

et al. 2007

A&A

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In December 2004, the soft gamma-ray repeater SGR 1806−20 emitted the most powerful giant flare ever observed. This probably involved a large-scale rearrangement of the magnetosphere leading to observable variations in the properties of its X-ray emission. Here we present the results of the first Suzaku observation of SGR 1806−20, together with almost simultaneous observations with XMM-Newton and INTEGRAL. The source seems to have reached a state characterized by a flux close to the pre-flare level and by a relatively soft spectrum. Despite this, SGR 1806−20 also remained quite active after the giant flare, allowing us to study several short bursts observed by Suzaku in the 1-100 keV range. We discuss the broad-band spectral properties of SGR 1806−20, covering both persistent and bursting emission, in the context of the magnetar model, and consider its recent theoretical developments.

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Section: Discussionmentioning

confidence: 99%

SGR 1806-20 about two years after the giant flare:Suzaku,XMM-Newton andINTEGRAL observations

Esposito

Mereghetti

Tiengo

et al. 2007

A&A

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“…cyclotron scattering ( Rea et al 2007), or more recently, a magnetized atmosphere model with the inclusion of scattering (Guver et al 2007). From the point of view of phase-averaged spectral analysis alone, these models are generally statistically acceptable, and therefore, none can be ruled out a priori.…”

Section: Introductionmentioning

confidence: 99%

Constraints on the Emission and Viewing Geometry of the Transient Anomalous X‐Ray Pulsar XTE J1810−197

Perna

Gotthelf

2008

ApJ

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The temporal decay of the flux components of the transient anomalous X-ray pulsar XTE J1810À197 following its 2002 outburst presents a unique opportunity to probe the emission geometry of a magnetar. Toward this goal, we model the magnitude of the pulsar's modulation in narrow spectral bands over time. Following previous work, we assume that the postoutburst flux is produced in two distinct thermal components arising from a hot spot and a warm concentric ring. We include general relativistic effects on the blackbody spectra due to gravitational redshift and light bending near the stellar surface, which strongly depend on radius. This affects the model fits for the temperature and size of the emission regions. For the hot spot, the observed temporal and energy-dependent pulse modulation is found to require an anisotropic, pencil-beamed radiation pattern. We are able to constrain an allowed range for the angles that the line of sight ( ) and the hot spot pole () make with respect to the spin axis. Within errors, this is defined by the locus of points in the -plane that lie along the line þ (R) ½ þ (R) ½ %const, where (R) is a function of the radius R of the star. For a canonical value of R ¼ 12 km, the viewing parameters range from ¼ ¼ 37 to ( ; ) ¼ (85 ; 15 ). We discuss our results in the context of magnetar emission models.

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“…Their high‐energy emission (∼0.5−100 keV) is traditionally modelled by an absorbed blackbody ( kT ∼ 0.4 keV) and two power laws (Γ soft ∼ 3 and Γ hard ∼ 1), although recently several attempts have been made to apply more physical spectral models (e.g. Perna et al 2001; Rea et al 2007a,b; Rea et al, in preparation).…”

Section: Introductionmentioning

confidence: 99%

Very deep X-ray observations of the anomalous X-ray pulsar 4U 0142+614

Rea

Nichelli

Israel

et al. 2007

Monthly Notices of the Royal Astronomical Society

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We report on two new XMM–Newton observations of the anomalous X‐ray pulsar (AXP) 4U 0142+614 performed in 2004 March and July, collecting the most accurate spectrum for this source. Furthermore, we analyse two short archival observations performed in 2002 February and 2003 January in order to study the long‐term behaviour of this AXP. 4U 0142+614 appears to be relatively steady in flux between 2002 and 2004, and the phase‐averaged spectrum does not show any significant variability between the four epochs. We derive the deepest upper limits to date on the presence of lines in 4U 0142+614 spectrum as a function of energy: equivalent width in the 1–3 keV energy range <4 and <8 eV for narrow and broad lines, respectively. A remarkable energy dependence in both the pulse profile and the pulsed fraction is detected, and consequently pulse–phase spectroscopy shows spectral variability as a function of phase. By making use of XMM–Newton and INTEGRAL data, we successfully model the 1–250 keV spectrum of 4U 0142+614 with three models, namely the canonical absorbed blackbody plus two power laws, a resonant cyclotron scattering model plus one power‐law and two log‐parabolic functions.

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Our distorted view of magnetars: application of the resonant cyclotron scattering model

Cited by 20 publications

References 20 publications

SGR 1806-20 about two years after the giant flare:Suzaku,XMM-Newton andINTEGRAL observations

SGR 1806-20 about two years after the giant flare:Suzaku,XMM-Newton andINTEGRAL observations

Constraints on the Emission and Viewing Geometry of the Transient Anomalous X‐Ray Pulsar XTE J1810−197

Very deep X-ray observations of the anomalous X-ray pulsar 4U 0142+614

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