A study of the interstellar medium towards the unidentified dark TeV $\gamma$-ray sources HESS J1614-518 and HESS J1616-508

Abstract

HESS J1614$-$518 and HESS J1616$-$508 are two tera-electron volt (TeV) $\gamma$-ray sources that are not firmly associated with any known counterparts at other wavelengths. We investigate the distribution of interstellar medium towards the TeV $\gamma$-ray sources using results from a 7 mm-wavelength Mopra study, the Mopra Southern Galactic Plane CO Survey, the Millimetre Astronomer's Legacy Team - 45 GHz survey and [CI] data from the HEAT telescope. Data in the CO(1$-$0) transition lines reveal diffuse gas overlapping the two TeV sources at several velocities along the line of sight, while observations in the CS(1$-$0) transition line reveal several interesting dense gas features. To account for the diffuse atomic gas, archival HI data was taken from the Southern Galactic Plane Survey. The observations reveal gas components with masses $\sim 10^3$ to $10^5$ M${}_{\odot }$ and with densities $\sim 10^2$ to $10^3$ cm${}^{-3}$ overlapping the two TeV sources. Several origin scenarios potentially associated with the TeV $\gamma$-ray sources are discussed in light of the distribution of the local interstellar medium. We find no strong convincing evidence linking any counterpart with HESS J1614$-$518 or HESS J1616$-$508.

25 pages, 14 figures, 6 tables, accepted for publication by PASA

References in corpus (5)

• HESS J1616-508: likely powered by PSR J1617-5055
• The Mopra Southern Galactic Plane CO Survey - Data Release 1
• MALT-45: A 7 mm survey of the southern Galaxy - I. Techniques and spectral line data
• Interstellar gas towards the TeV gamma-ray sources HESS J1640-465 and HESS J1641-463
• An Atomic and Molecular Study of the Interstellar Medium Around the SNR RCW 103

Cited by in corpus (1)

• The Mopra Southern Galactic Plane CO Survey - Data Release 3