On the nature of some SGRs and AXPs as rotation-powered neutron stars

Abstract

We investigate the possibility that some SGRs/AXPs could be canonical rotation-powered pulsars using realistic NS structure parameters instead of fiducial values. We show that realistic NS parameters lowers the estimated value of the magnetic field and radiation efficiency, $L_X/{\dot{E}}_{\mathrm{rot}}$, 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 $L_X/{\dot{E}}_{\mathrm{rot}}<1$. 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 $L_X/{\dot{E}}_{\mathrm{rot}}>1$ in two of them. 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 $L_X/{\dot{E}}_{\mathrm{rot}}<1$ 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.

11 pages, 14 figures, to appear in A&A

References in corpus (18)

• Shapiro delay measurement of a two solar mass neutron star
• A Massive Pulsar in a Compact Relativistic Binary
• The strongest cosmic magnets: Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars
• Transient pulsed radio emission from a magnetar
• 1E 1547.0-5408: a radio-emitting magnetar with a rotation period of 2 seconds
• Magnetar-like Emission from the Young Pulsar in Kes 75
• A downward revision to the distance of the 1806-20 cluster and associated magnetar from Gemini near-Infrared spectroscopy
• The magnetar 1E 1547.0-5408: radio spectrum, polarimetry, and timing
• Magnetars as persistent hard X-ray sources: INTEGRAL discovery of a hard tail in SGR 1900+14
• A Magnetar-like Outburst from a High-B Radio Pulsar
• Polarized radio emission from a magnetar
• Radio emission evolution, polarimetry and multifrequency single pulse analysis of the radio magnetar PSR J1622-4950
• Neutron star equilibrium configurations within a fully relativistic theory with strong, weak, electromagnetic, and gravitational interactions
• The fundamental plane for radio magnetars
• The first XMM-Newton observations of the Soft Gamma-ray Repeater SGR 1900+14
• The superflares of soft Gamma-ray repeatres: giant quakes in solid quark stars?
• SGR 1806-20 about two years after the giant flare: Suzaku, XMM-Newton and INTEGRAL observations
• On the Magnetic Field of Pulsars with Realistic Neutron Stars Configurations

Cited by in corpus (2)

• The Dipole Magnetic Field and Spin-down Evolutions of The High Braking Index Pulsar PSR J1640-4631
• Expansion of magnetic neutron stars in an energy (in)dependent spacetime