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
Potential energy
Potential energy surface
Collisional excitation
Interstellar cloud
Interstellar medium
Rotational temperature
Astrophysics
Molecule
Ion
Stars
Ionization
Quantum mechanics
Galaxy
Quantum dynamics
Atomic and molecular collisions
Physics
Atomic physics
Radiative transfer
Excitation
Ab initio
Molecular cloud
Excited state