Spatially resolved X-ray spectra of the Galactic SNR G18.95-1.1: SRG/eROSITA view

Abstract

Aims. We study the X-ray emission of the galactic supernova remnant (SNR) G18.95-1.1 with the eROSITA telescope on board the Spectrum Rentgen Gamma (SRG) orbital observatory. In addition to the pulsar wind nebula that was previously identified and examined by ASCA and Chandra, we study the X-ray spectra of the bright SNR ridge, which is resolved into a few bright clumps. Methods. The wide field of view and the large collecting area in the 0.2-2.3 keV energy range of SRG/eROSITA allowed us to perform spatially resolved spectroscopy of G18.95-1.1. Results. The X-ray ridge of G18.95-1.1 is asymmetric, indicating either supernova ejecta asymmetry or their interaction with a cloud. The X-ray dim northern regions outside the pulsar wind nebula can be described by a thin thermal plasma emission with a temperature ~0.3 keV and a solar composition. The X-ray spectra of a few bright clumps located along the southern ridge may be satisfactorily approximated by a single thermal component of the Si-rich ejecta at the collisional ionization equilibrium with a temperature of about 0.3 keV. The bright ridge can be alternatively fit with a single component that is not dominated by equilibrium ejecta with T ~ 0.6 keV. The high ratio of the derived Si/O abundances indicates that the ejecta originated in deep layers of the progenitor star. The plasma composition of a southern Si-rich clump and the bright ridge are similar to what was earlier found in the Vela shrapnel A and G.

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