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

Esposito, P.; Mereghetti, S.; Tiengo, A.; Zane, S.; Turolla, R.; Götz, D.; Rea, N.; Kawai, N.; Ueno, Masaru; Israel, G. L.; Stella, L.; Feroci, M.

doi:10.1051/0004-6361:20078562

Cited by 47 publications

(41 citation statements)

References 54 publications

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“…SGR 1806-20: in this case we have k B T BB = 0.55 keV and R BB = 3.7 km, assuming a distance of 15 kpc (Esposito et al 2007). For this source F X = 1.8 × 10 −11 erg cm −2 s −1 , and we infer F BB X = 0.16F X and F PL X = 0.84F X .…”

Section: Sgrs and Axps Efficiencymentioning

confidence: 81%

The rotation-powered nature of some soft gamma-ray repeaters and anomalous X-ray pulsars

Coelho

Cáceres

Lima

et al. 2017

A&A

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Context. Soft gamma repeaters (SGRs) and anomalous X-ray pulsars (AXPs) are slow rotating isolated pulsars whose energy reservoir is still matter of debate. Adopting neutron star (NS) fiducial parameters; mass M = 1.4M , radius R = 10 km, and moment of inertia, I = 10 45 g cm 2 , the rotational energy loss,Ė rot , is lower than the observed luminosity (dominated by the X-rays) L X for many of the sources. Aims. We investigate the possibility that some members of this family could be canonical rotation-powered pulsars using realistic NS structure parameters instead of fiducial values. Methods. We compute the NS mass, radius, moment of inertia and angular momentum from numerical integration of the axisymmetric general relativistic equations of equilibrium. We then compute the entire range of allowed values of the rotational energy loss,Ė rot , for the observed values of rotation period P and spin-down rateṖ. We also estimate the surface magnetic field using a general relativistic model of a rotating magnetic dipole. Results. We show that realistic NS parameters lowers the estimated value of the magnetic field and radiation efficiency, L X /Ė rot , with respect to estimates based on fiducial NS parameters. We show that nine SGRs/AXPs can be described as canonical pulsars driven by the NS rotational energy, for L X computed in the soft (2-10 keV) X-ray band. We compute the range of NS masses for which L X /Ė rot < 1. We discuss the observed hard X-ray emission in three sources of the group of nine potentially rotation-powered NSs. This additional hard X-ray component dominates over the soft one leading to L X /Ė rot > 1 in two of them. Conclusions. We show that 9 SGRs/AXPs can be rotation-powered NSs if we analyze their X-ray luminosity in the soft 2-10 keV band. Interestingly, four of them show radio emission and six have been associated with supernova remnants (including Swift J1834.9-0846 the first SGR observed with a surrounding wind nebula). These observations give additional support to our results of a natural explanation of these sources in terms of ordinary pulsars. Including the hard X-ray emission observed in three sources of the group of potential rotation-powered NSs, this number of sources with L X /Ė rot < 1 becomes seven. It remains open to verification 1) the accuracy of the estimated distances and 2) the possible contribution of the associated supernova remnants to the hard X-ray emission.

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Section: Sgrs and Axps Efficiencymentioning

confidence: 81%

The rotation-powered nature of some soft gamma-ray repeaters and anomalous X-ray pulsars

Coelho

Cáceres

Lima

et al. 2017

A&A

View full text Add to dashboard Cite

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“…The burst spectra in the hard X-ray range (above ∼15 keV) are well fit by optically thin thermal bremsstrahlung models with temperature kT∼30-40 keV. When also lower energy data are included, a model consisting of the sum of two blackbody functions, with temperatures kT 1 ∼2-4 keV and kT 2 ∼8-12 keV, provides a better description of the burst spectra [51,149,47,100].…”

Section: Bursts and Flaresmentioning

confidence: 88%

Pulsars and Magnetars

Mereghetti

2013

Braz J Phys

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The high-energy sources known as anomalous X-ray pulsars (AXPs) and soft γ-ray repeaters (SGRs) are well explained as magnetars: isolated neutron stars powered by their own magnetic energy. After explaining why it is generally believed that the traditional energy sources at work in other neutron stars (accretion, rotation, residual heat) cannot power the emission of AXPs/SGRs, I review the observational properties of the twenty AXPs/SGRs currently known and describe the main features of the magnetar model. In the last part of this review I discuss the recent discovery of magnetars with low external dipole field and some of the relations between AXPs/SGRs and other classes of isolated neutron stars.

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“…The hardest spectra of SGRs made them more promising targets for hard X-ray telescopes, and indeed some indication for the presence of hard tails in SGRs were already present in earlier data. For example, in 1997 BeppoSAX detected a significant emission in the 20-150 keV range, most likely originating from SGR 1900+14 [63]. However, only with the imaging capability of the INTEGRAL IBIS telescope it was possible to unambiguously confirm the presence of persistent hard X-ray emission in two SGRs [186; 96].…”

Section: Hard X-ray Emissionmentioning

confidence: 99%

The strongest cosmic magnets: soft gamma-ray repeaters and anomalous X-ray pulsars

Mereghetti

2008

Astron Astrophys Rev

696

766

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Two classes of X-ray pulsars, the Anomalous X-ray Pulsars and the Soft Gamma-ray Repeaters, have been recognized in the last decade as the most promising candidates for being magnetars: isolated neutron stars powered by magnetic energy. I review the observational properties of these objects, focussing on the most recent results, and their interpretation in the magnetar model. Alternative explanations, in particular those based on accretion from residual disks, are also considered. The possible relations between these sources and other classes of neutron stars and astrophysical objects are also discussed.

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

Cited by 47 publications

References 54 publications

The rotation-powered nature of some soft gamma-ray repeaters and anomalous X-ray pulsars

The rotation-powered nature of some soft gamma-ray repeaters and anomalous X-ray pulsars

Pulsars and Magnetars

The strongest cosmic magnets: soft gamma-ray repeaters and anomalous X-ray pulsars

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