Star Forming Dense Cloud Cores in the TeV {\gamma}-ray SNR RX J1713.7-3946

TL;DR

This study investigates dense molecular cloud cores within the supernova remnant RX J1713.7-3946, revealing their role in star formation, their interaction with the SNR shock, and their association with enhanced synchrotron X-ray emission.

Contribution

It provides new molecular observations of dense cloud cores in RX J1713.7-3946, demonstrating their survival against shock waves and their influence on particle acceleration and X-ray emission.

Findings

Dense cloud cores are associated with enhanced X-ray emission.

Peak C shows active star formation signs.

Dense cores can survive shock erosion and induce turbulence.

Abstract

RX J1713.7-3946 is one of the TeV {\gamma}-ray supernova remnants (SNRs) emitting synchrotron X rays. The SNR is associated with molecular gas located at ~1 kpc. We made new molecular observations toward the dense cloud cores, peaks A, C and D, in the SNR in the 12CO(J=2-1) and 13CO(J=2-1) transitions at angular resolution of 90". The most intense core in 13CO, peak C, was also mapped in the 12CO(J=4-3) transition at angular resolution of 38". Peak C shows strong signs of active star formation including bipolar outflow and a far-infrared protostellar source and has a steep gradient with a r^{-2.2$\pm$0.4} variation in the average density within radius r. Peak C and the other dense cloud cores are rim-brightened in synchrotron X rays, suggesting that the dense cloud cores are embedded within or on the outer boundary of the SNR shell. This confirms the earlier suggestion that the X rays are physically associated with the molecular gas (Fukui et al. 2003). We present a scenario where the densest molecular core, peak C, survived against the blast wave and is now embedded within the SNR. Numerical simulations of the shock-cloud interaction indicate that a dense clump can indeed survive shock erosion, since shock propagation speed is stalled in the dense clump. Additionally, the shock-cloud interaction induces turbulence and magnetic field amplification around the dense clump that may facilitate particle acceleration in the lower-density inter-clump space leading to the enhanced synchrotron X rays around dense cores.