Connecting the ISM to TeV PWNe and PWN candidates
Abstract
We investigate the interstellar medium towards seven TeV gamma-ray sources thought to be pulsar wind nebulae using Mopra molecular line observations at 7 mm [CS(1-0), SiO(1-0, v = 0)], Nanten CO(1-0) data and the Southern Galactic Plane Survey/GASS Hi survey. We have discovered several dense molecular clouds co-located to these TeV gamma-ray sources, which allows us to search for cosmic rays coming from progenitor SNRs or, potentially, from pulsar wind nebulae. We notably found SiO(1-0, v = 0) emission towards HESS J1809-193, highlighting possible interaction between the adjacent supernova remnant SNR G011.0-0.0 and the molecular cloud at d ∼ 3.7 kpc. Using morphological features, and comparative studies of our column densities with those obtained from X-ray measurements, we claim a distance d ∼ 8.6 - 9.7kpc for SNR G292.2-00.5, d ∼ 3.5 - 5.6 kpc for PSR J1418-6058 and d ∼ 1.5 kpc for the new SNR candidate found towards HESS J1303-631. From our mass and density estimates of selected molecular clouds, we discuss signatures of hadronic/leptonic components from pulsar wind nebulae and their progenitor SNRs. Interestingly, the molecular gas, which overlaps HESS J1026-582 at d ∼ 5 kpc, may support a hadronic origin. We find however that this scenario requires an undetected cosmic-ray accelerator to be located at d < 10 pc from the molecular cloud. For HESS J1809-193, the cosmic rays which have escaped SNR G011.0-0.0 could contribute to the TeV gamma-ray emission. Finally, from the hypothesis that at most 20% the pulsar spin down power could be converted into CRs, we find that among the studied pulsar wind nebulae, only those from PSR J1809-1917 could potentially contribute to the TeV emission.
- Publication:
-
Publications of the Astronomical Society of Australia
- Pub Date:
- March 2019
- DOI:
- 10.1017/pasa.2019.7
- arXiv:
- arXiv:1905.04517
- Bibcode:
- 2019PASA...36...14V
- Keywords:
-
- gamma rays: ISM;
- ISM: clouds;
- ISM: cosmic rays;
- ISM: individual objects (HESS J1809-193;
- HESS J1026-589;
- HESS J1119-614;
- HESS J1418-609;
- HESS J1420-607;
- HESS J1303-631;
- HESS J1018-589);
- ISM: supernova remnants;
- molecular data;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 42 pages, 21 figures, 15 tables. Published in PASA