Collisional excitation of PO+ by para-H2: Potential energy surface, scattering calculations and astrophysical applications
Résumé
We report the derivation of rate coefficients for rotational (de-)excitation PO+ induced by collisions with H2. The calculations were performed on a four-dimensional potential energy surface, obtained top highly accurate ab initio points. Preliminary tests pointed out low influence coupling between j = 0 and higher levels H2 cross sections values, thus allowing to neglect structure On this basis, state-to-state collisional derived temperatures ranging from 5 200 K. Radiative transfer have been used model recent observation in G+0.693-0.027 molecular cloud, order evaluate possible impact non-LTE models determination its physical conditions. column density was found be approximately ∼ 3.7 × 1011 cm−2, which is 60% (a factor 1.7) smaller than previously LTE-derived value. Extensive simulations show that low-j lines exhibit maser behavior at densities 104 106 cm−3, highlighting importance proper treatment accurately emissions interstellar medium.
Mots clés
- Atomic and molecular collisions
- Quantum dynamics
- Galaxy
- Quantum mechanics
- Ionization
- Stars
- Ion
- Molecule
- Astrophysics
- Rotational temperature
- Interstellar medium
- Interstellar cloud
- Collisional excitation
- Potential energy surface
- Potential energy
- Excited state
- Molecular cloud
- Ab initio
- Excitation
- Radiative transfer
- Atomic physics
- Physics