Collisional Pumping of OH Masers near Supernova Remnants

Abstract

The collisional pumping of OH masers in non-dissociative C-type shocks near supernova remnants is considered. The emergence of maser emission in OH lines is investigated for various shock parameters - the shock speed, the preshock gas density, the cosmic-ray ionization rate, and the magnetic field strength. The largest optical depth in the 1720 MHz line is reached at high gas ionization rates $\zeta \ge 10^{-15}$ s${}^{-1}$, an initial density $n_{\mathrm{H},0}\le 2\times 10^4$ cm${}^{-3}$, and a shock speed $u_{\mathrm{s}}\ge 20$ km s${}^{-1}$. According to our calculations, there is also a level population inversion for the 6049 and 4765 MHz transitions of excited OH rotational states. However, the optical depth in these lines is small for all of the investigated shock parameters, which explains the non-detection of maser emission in these lines in supernova remnants.

arXiv comment17 pages, 4 figures

References in corpus (34)

• An atomic and molecular database for analysis of submillimetre line observations
• The UMIST database for astrochemistry 2012
• Photodissociation and photoionisation of atoms and molecules of astrophysical interest
• Gas and grain chemical composition in cold cores as predicted by the Nautilus 3-phase model
• SiO line emission from C-type shock waves : interstellar jets and outflows
• OH 1720 MHz Masers in Supernova Remnants --- C-Shock Indicators
• Shock Excited Maser Emission from the Supernova Remnant W28
• Class I methanol masers in the outflow of IRAS 16547-4247
• Molecular ions in the protostellar shock L1157-B1
• Enhanced OH in C-type shock waves in molecular clouds
• OH(1720 MHz) Masers As Signposts of Molecular Shocks
• OH (1720 MHz) Masers and Mixed-Morphology Supernova Remnants
• OH Zeeman Magnetic Field Detections Toward Five Supernova Remnants Using the VLA
• Cosmic ray induced ionisation of a molecular cloud shocked by the W28 supernova remnant
• GBT Observations of IC 443: the Nature of OH(1720 MHz) Masers and OH Absorption
• Correlation of Supernova Remnant Masers and Gamma-Ray Sources
• 5cm OH masers as diagnostics of physical conditions in star-forming regions
• OH (1720 MHz) Masers: A Multiwavelength Study of the Interaction between the W51C Supernova Remnant and the W51B Star Forming Region
• OH maser emission in the THOR survey of the northern Milky Way
• The OH (1720 MHz) Supernova Remnant Masers in W44: MERLIN and VLBA Polarization Observations
• The OH (1720 MHz) Supernova Remnant Masers in W28: MERLIN and VLBA Polarization Observations
• Excited-state OH Masers and Supernova Remnants
• On the Inference of the Cosmic Ray Ionization Rate $\zeta$ from the HCO${}^{+}$-to-DCO${}^{+}$ Abundance Ratio: The Effect of Nuclear Spin
• Constraining the cosmic ray spectrum in the vicinity of the supernova remnant W28: from sub-GeV to multi-TeV energies
• Modelling CH${}_3$OH masers: Sobolev approximation and accelerated lambda iteration method
• Accurate OH Maser Positions From The SPLASH Survey III: The Final 96 Square Degrees
• Chemical evolution of the gas in C-type shocks in dark clouds
• NH${}_3$(3,3) and CH${}_3$OH near Supernova Remnants: GBT and VLA Observations
• A search for OH 6 GHz maser emission towards supernova remnants
• Effelsberg Observations of Excited-State (6.0 GHz) OH in Supernova Remnants and W3(OH)
• Theoretical study of ionization profiles of molecular clouds near supernova remnants: Tracing the hadronic origin of GeV gamma radiation
• C-type shock modelling -- the effect of new H${}_2$-H collisional rate coefficients
• OH Masers and Supernova Remnants
• A Survey for Ground-State OH Masers Toward a Sample of Herbig-Haro Objects

Cited by in corpus (2)

• Modelling cosmic masers in C-type shock waves -- the coexistence of Class I CH3OH and 1720 MHz OH masers
• Collisional Pumping of H${}_2$O and CH${}_3$OH Masers in C-Type Shock Waves