XMM-Newton Observations of Two Candidate Supernova Remnants

TL;DR

This study uses XMM-Newton observations to investigate candidate supernova remnants, identifying pulsar-wind nebulae and other high-energy sources, and discusses their possible associations and classifications in the Galactic plane.

Contribution

First detailed X-ray analysis of candidate SNRs G23.5+0.1 and G25.5+0.0, revealing PWN candidates and clarifying their nature and possible associations.

Findings

Detected a PWN candidate near PSR B1830-08 in G23.5+0.1

Identified a PWN and a candidate radio galaxy in G25.5+0.0

No evidence of SNR emission in G25.5+0.0 field

Abstract

Candidate supernova remnants G23.5+0.1 and G25.5+0.0 were observed by XMM-Newton in the course of a snap-shot survey of plerionic and composite SNRs in the Galactic plane. In the field of G23.5+0.1, we detected an extended source, ~3' in diameter, which we tentatively interpret as a pulsar-wind nebula (PWN) of the middle-aged radio pulsar B1830-08. Our analysis suggests an association between PSR B1830-08 and the surrounding diffuse radio emission. If the radio emission is due to the SNR, then the pulsar must be significantly younger than its characteristic age. Alternatively, the radio emission may come from a relic PWN. In the field of G25.5+0.0, which contains the extended TeV source HESS J1837-069, we detected the recently discovered young high-energy pulsar J1838-0655 embedded in a PWN with extent of 1.3'. We also detected another PWN candidate (AX J1837.3-0652) with an extent of 2' and unabsorbed luminosity L_(2-10 keV) ~ 4 x 10^33 erg/s at d=7 kpc. The third X-ray source, located within the extent of the HESS J1837-069, has a peculiar extended radio counterpart, possibly a radio galaxy with a double nucleus or a microquasar. We did not find any evidence of the SNR emission in the G25.5+0.0 field. We provide detailed multiwavelength analysis and identifications of other field sources and discuss robustness of the G25.5+0.0 and G23.5+0.1 classifications as SNRs. (abstract abridged)