Spatially resolved spectroscopy of nonthermal X-rays in RX J1713.7-3946 with Chandra

TL;DR

This study uses Chandra to perform spatially resolved spectroscopy of RX J1713.7-3946, revealing significant variations in nonthermal X-ray emission and photon indices across different regions, linked to shock-cloud interactions.

Contribution

It provides detailed spatially resolved X-ray spectral analysis of RX J1713.7-3946, highlighting regional differences and their possible origins in shock-cloud interactions.

Findings

Photon indices vary significantly among subregions (1.8 to 3.0).

Filaments in the SE are harder ({b2} b2 2.0) than surroundings.

Hard regions are located near interstellar gas peaks, suggesting shock-cloud interactions.

Abstract

The young shell-type supernova remnant (SNR) RX J1713.7-3946 has been studied as a suitable target to test the SNR paradigm for the origin of Galactic cosmic rays. We present a spatially resolved spectroscopy of the nonthermal X-ray emission in RX J1713.7-3946 with Chandra. In order to obtain X-ray properties of the filamentary structures and their surrounding regions, we divide the southeastern (SE), southwestern (SW), and northwestern (NW) parts of the SNR into subregions on the typical order of several 10" and extract spectra from each subregion. Their photon indices are significantly different among the subregions with a range of 1.8 < {\Gamma} < 3. In the SE part, the clear filaments are harder ({\Gamma} ~ 2.0) than the surrounding regions. This is a common feature often observed in young SNRs and naturally interpreted as a consequence of synchrotron cooling. On the other hand, the bright filamentary regions do not necessarily coincide with the hardest regions in the SW and NW parts. We also find the SW filamentary region is rather relatively soft ({\Gamma} ~ 2.7). In addition, we find that hard regions with photon indices of 2.0-2.2 exist around the bright emission although they lie in the downstream region and does not appear to be the blast wave shock front. Both two aforementioned characteristic regions in SW are located close to peaks of the interstellar gas. We discuss possible origins of the spatial variation of the photon indices, paying particular attention to the shock-cloud interactions.