A new study of the supernova remnant G344.7-0.1 located in the vicinity of the unidentified TeV source HESS J1702-420

Context. The identification of counterparts of dark gamma-ray sources adds greatly to our understanding of their underlying astrophysical processes.
Aims: We investigate the physical properties of the supernova remnant (SNR) G344.7-0.1, to clarify whether it hosts a pulsar wind nebula (PWN), and the possible physical relationship between the SNR and the gamma-ray source HESS J1702-420.
Methods: The research was carried out based on new high-resolution radio images produced from archival ATCA and VLA data in combination with X-ray archival XMM-Newton data. The ambient interstellar medium was investigated in HI, ¹²CO and mid IR (λ 24 μm) with data from the public SGPS, CfA CO and MIPSGAL surveys, respectively.
Results: Based on the radio images and the comparison with X-ray and IR observations, we confirm that there is no PWN within G344.7-0.1; the observed emission highlights sites where the SN blast wave is encountering dense material. No radio counterpart is found for the X-ray object CXOU J170357.8-414302. The X-ray radiation completely fills in the interior of the SNR, being thermal in nature and originating in heated ejecta. From the spectral analysis it is inferred that G344.7-0.1 is the result of a core-collapse SN that exploded about 3000 yr ago. On the basis of HI absorption and emission we redetermined its distance in (6.3 ± 0.1) kpc. From the study of the surrounding gas, we conclude that G344.7-0.1 has evolved within an HI bubble created by the SN precursor. This bubble is, in turn, part of a larger HI/IR ring created by the stellar wind of prior-generation stars, about 2.6 × 10⁶ yr ago. A second generation of stars formed in this compressed gas and about 3000 yr ago one of these stars exploded, creating the SNR G344.7-0.1. This study suggests that G344.7-0.1 and its turbulent environment is a plausible counterpart for HESS J1702-420.