X-ray and radio studies of SNR CTB 37B hosting the magnetar CXOU J171405.7−381031

Abstract

ABSTRACT We present a Chandra and XMM–Newton study of the supernova remnant (SNR) CTB 37B, along with archival radio observations. In radio wavelengths, the SNR CTB 37B is an incomplete shell showing bright emission from the eastern side, while the X-ray morphology shows diffuse emission from regions surrounding the magnetar CXOU J171405.7–381031. We used archival H i absorption measurements to constrain the distance to the remnant and obtain D = 9.8 ± 1.5 kpc. The X-ray spectrum of the remnant is described by a thermal model in the 1–5 keV energy range, with a temperature of kT = 1.3 ± 0.1 keV. The abundances from the spectral fits are consistent with being solar or sub-solar. A small region of diffuse emission is seen to the southern side of the remnant, best fitted by a non-thermal spectrum with an unusually hard photon index of Γ = 1.3 ± 0.3. Assuming a distance of 9.8 kpc to the SNR, we infer a shock velocity of Vs = 915 ± 70 km s−1 and an explosion energy of E = (1.8 ± 0.6) × 1050 erg. The overall imaging and spectral properties of CTB 37B favour the interpretation of a young SNR (≲6200 yr old), propagating in a low-density medium under the assumption of a Sedov evolutionary phase.