H3+ absorption and emission in local (U)LIRGs with JWST/NIRSpec: Evidence for high H2 ionization rates
We study the 3.4 - 4.4 mu m fundamental rovibrational band of H3+, a key tracer of the ionization of the molecular interstellar medium (ISM), in a sample of 12 local (d 4 x 10-15 s-1, which are likely associated with high-energy cosmic rays. In half of the targets, the absorptions are blueshifted by...
| Autores: | , , , , , , , , |
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| Tipo de recurso: | artículo |
| Fecha de publicación: | 2024 |
| País: | España |
| Institución: | Universidad de Alcalá (UAH) |
| Repositorio: | e_Buah Biblioteca Digital Universidad de Alcalá |
| Idioma: | inglés |
| OAI Identifier: | oai:ebuah.uah.es:10017/67606 |
| Acceso en línea: | http://hdl.handle.net/10017/67606 https://dx.doi.org/10.1051/0004-6361/202451741 |
| Access Level: | acceso abierto |
| Palabra clave: | Cosmic rays ISM: molecules Galaxies: active Galaxies: starburst Infrared: ISM Astronomía Astronomy |
| Sumario: | We study the 3.4 - 4.4 mu m fundamental rovibrational band of H3+, a key tracer of the ionization of the molecular interstellar medium (ISM), in a sample of 12 local (d 4 x 10-15 s-1, which are likely associated with high-energy cosmic rays. In half of the targets, the absorptions are blueshifted by 50-180 km s-1, which is lower than the molecular outflow velocities measured using other tracers such as OH 119 mu m or rotational CO lines. This suggests that H3+ traces gas close to the outflow-launching sites before it has been fully accelerated. We used nonlocal thermodynamic equilibrium models to investigate the physical conditions of these clouds. In seven out of ten objects, the H3+ excitation is consistent with inelastic collisions with H2 in warm translucent molecular clouds (Tkin similar to 250-500 K and n(H2) similar to 102 - 3 cm-3). In three objects, dominant infrared pumping excitation is required to explain the absorptions from the (3,0) and (2,1) levels of H3+ detected for the first time in the ISM. |
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