Two Magnetar Candidates in HESS Supernova Remnants

TL;DR

This paper reports the identification of two candidate magnetars in supernova remnants associated with HESS sources, providing new insights into their properties and potential contributions to TeV emission.

Contribution

The study presents the discovery of two new magnetar candidates in HESS SNRs, including their X-ray spectral features and pulsation evidence, expanding known magnetar/SNR associations.

Findings

One candidate shows a 3.82 s pulsation with significant pulsed fraction.

Spectral analysis reveals AXP-like soft X-ray spectra.

Potential contribution of these magnetars to diffuse TeV emission.

Abstract

We identify two candidate magnetars in archival X-ray observations of HESS detected shell-type SNRs. X-ray point sources in CTB 37B coincident with HESS J1713-381 and in G353.6-0.7 coincident with HESS J1731-347 both have AXP-like spectra, much softer than those of ordinary, rotation powered pulsars, and no optical/IR counterparts. The spectrum of CXOU J171405.7-381031 in CTB 37B has a hard excess above 6 keV, which may be similar to such components seen in some AXPs. A new Chandra observation of this object reveals a highly significant pulsed signal at P = 3.82 s with pulsed fraction f_p = 0.31. Analysis of an XMM-Newton observation of the second candidate, XMMU J173203.3-344518 in G353.6-0.7, yields only marginal evidence for a 1 s period. If it is not a magnetar, then it could be a weakly magnetized central compact object (CCO). Considering that these HESS sources previously attributed to the SNR shells are possibly centrally peaked, we hypothesize that their pulsars may contribute to diffuse TeV emission. These identifications potentially double the number of magnetar/SNR associations in the Galaxy, and can be used to investigate the energetics and asymmetries of the supernovae that give rise to magnetars.