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Unusually high HCO+/CO ratios in and outside supernova remnant W49B
- Source :
- The Astrophysical Journal, 931(2):144, Astrophysical Journal, 931(2):144. IOP Publishing Ltd.
- Publication Year :
- 2022
-
Abstract
- Galactic supernova remnants (SNRs) and their environments provide the nearest laboratories to study SN feedback. We performed molecular observations toward SNR W49B, the most luminous Galactic SNR in the X-ray band, aiming to explore signs of multiple feedback channels of SNRs on nearby molecular clouds (MCs). We found very broad HCO+ lines with widths of dv = 48--75 km/s in the SNR southwest, providing strong evidence that W49B is perturbing MCs at a systemic velocity of $V_{LSR}=61$--65 km/s, and placing W49B at a distance of $7.9\pm 0.6$ kpc. We observed unusually high-intensity ratios of HCO+ J=1-0/CO J=1-0 not only at shocked regions ($1.1\pm 0.4$ and $0.70\pm 0.16$), but also in quiescent clouds over 1 pc away from the SNR's eastern boundary (> 0.2). By comparing with the magnetohydrodynamics shock models, we interpret that the high ratio in the broad-line regions can result from a cosmic-ray (CR) induced chemistry in shocked MCs, where the CR ionization rate is enhanced to around 10--100 times of the Galactic level. The high HCO+/CO ratio outside the SNR is probably caused by the radiation precursor, while the luminous X-ray emission of W49B can explain a few properties in this region. The above results provide observational evidence that SNRs can strongly influence the molecular chemistry in and outside the shock boundary via their shocks, CRs, and radiation. We propose that the HCO+/CO ratio is a potentially useful tool to probe an SNR's multichannel influence on MCs.<br />19 pages, 11 figures, ApJ in press
- Subjects :
- High Energy Astrophysical Phenomena (astro-ph.HE)
Supernova remnants
FOS: Physical sciences
Astronomy and Astrophysics
X-ray sources
Astrophysics - Astrophysics of Galaxies
Space and Planetary Science
Astrophysics of Galaxies (astro-ph.GA)
Molecular clouds
Supernova remnants, Molecular clouds
Astrophysics - High Energy Astrophysical Phenomena
Cosmic rays
Shocks
Subjects
Details
- Language :
- English
- ISSN :
- 0004637X
- Database :
- OpenAIRE
- Journal :
- The Astrophysical Journal, 931(2):144, Astrophysical Journal, 931(2):144. IOP Publishing Ltd.
- Accession number :
- edsair.doi.dedup.....66da6eb3db4150513107b796d0c47adb