STAR-FORMING DENSE CLOUD CORES IN THE TeV GAMMA-RAY SNR RX J1713.7–3946

Abstract

RX J1713.7−3946 is one of the TeV γ-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 an angular resolution of 90''. The most intense core in 13CO, peak C, was also mapped in the 12CO(J = 4–3) transition at an 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±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. We present a scenario where the densest molecular core, peak C, survived 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 the 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 enhanced synchrotron X-rays around dense cores.