Is HESS J1912+101 associated with an old Supernova Remnant?

TL;DR

This study presents evidence linking HESS J1912+101 to an old supernova remnant through molecular and atomic gas observations, suggesting the TeV emission results from hadronic interactions with surrounding dense gas.

Contribution

It provides the first detailed analysis connecting the TeV source HESS J1912+101 with an old supernova remnant using multiwavelength gas data.

Findings

Identification of shocked molecular gas and high-velocity H i shells near HESS J1912+101.

Estimation of the SNR's distance as approximately 4.1 kpc.

Correlation between TeV emission and dense molecular gas supporting hadronic origin.

Abstract

HESS J1912+101 is a shell-like TeV source that has no clear counterpart in multiwavelength. Using CO and H i data, we reveal that VLSR~+60 km/s molecular clouds (MCs), together with shocked molecular gas and high-velocity neutral atomic shells, are concentrated toward HESS J1912+101. The prominent wing profiles up to VLSR~+80 km/s seen in 12CO (J=1-0 and J=3-2) data, as well as the high-velocity expanding H i shells up to VLSR~ +100 km/s, exhibit striking redshifted-broadening relative to the quiescent gas. These features provide compelling evidences for large-scale perturbation in the region. We argue that the shocked MCs and the high-velocity Hi shells may originate from an old supernova remnant (SNR). The distance to the SNR is estimated to be ~4.1 kpc based on the Hi self-absorption method, which leads to a physical radius of 29.0 pc for the ~(0.7-2.0)x10e5 years old remnant with an expansion velocity of >40 km/s. The +60 km/s MCs and the disturbed gas are indeed found to coincide with the bright TeV emission, supporting the physical association between them. Naturally, the shell-like TeV emission comes from the decay of neutral pions produced by interactions between the accelerated hadrons from the SNR and the surrounding high-density molecular gas.