An alternative interpretation of magnetars' traits deduced from the observational data on their outburst fluxes and spectra

Abstract

By applying the Efron-Petrosian method to the fluxes $S$ and distances $D$ of the magnetars listed in the Magnetar Outburst Online Catalogue, we show that the observational data are consistent with the dependence $S\propto D^{-3/2}$, which characterizes the emission from the superluminally moving current sheet in the magnetosphere of a non-aligned neutron star, at substantially higher levels of significance than they are with the dependence $S\propto D^{-2}$. This result agrees with that previously obtained by an analysis of the data in the McGill Online Magnetar Catalog and confirms that, contrary to the currently prevalent view, magnetars' X-ray luminosities do not exceed their spin-down luminosities. The X-ray spectra of magnetars, moreover, are congruous with the spectral energy distribution (SED) of a broadband non-thermal emission mechanism identical to that at play in rotation-powered pulsars: we show that the SED of the caustics that are generated in certain privileged directions by the magnetospheric current sheet single-handedly fits the observed spectra of 4U 0142+61, 1E 1841-045 and XTE J1810-197 over their entire breadths. Magnetars' outbursts and their associated radio bursts are predicted to occur when, as a result of large-scale timing anomalies (such as glitches, quakes or precession), one of the privileged directions along which the radiation from the current sheet decays more slowly than predicted by the inverse-square law either swings past or oscillates across the line of sight.