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http://hdl.handle.net/20.500.12386/34615
Title: | Cosmic-ray-induced H2 line emission: Astrochemical modeling and implications for JWST observations | Authors: | Brandt A. L. Gaches Shmuel Bialy Thomas G. Bisbas PADOVANI, Marco Daniel Seifried Stefanie Walch |
Issue Date: | 2022 | Journal: | ASTRONOMY & ASTROPHYSICS | Number: | 664 | First Page: | A150 | Abstract: | Context: It has been proposed that H$_2$ near-infrared lines may be excited by cosmic rays and allow for a determination of the cosmic-ray ionization rate in dense gas. One-dimensional models show that measuring both the H$_2$ gas column density and H$_2$ line intensity enables a constraint on the cosmic-ray ionization rate as well as the spectral slope of low-energy cosmic-ray protons in the interstellar medium (ISM). Aims: We aim to investigate the impact of certain assumptions regarding the H$_2$ chemical models and ISM density distributions on the emission of cosmic-ray induced H$_2$ emission lines. This is of particular importance for utilizing observations of these lines with the James Webb Space Telescope to constrain the cosmic-ray ionization rate. Methods: We compare the predicted emission from cosmic-ray induced, ro-vibrationally excited H$_2$ emission lines for different one- and three-dimensional models with varying assumptions on the gas chemistry and density distribution. Results: We find that the model predictions of the H$_2$ line intensities for the (1-0)S(0), (1-0)Q(2), (1-0)O(2) and (1-0)O(4) transitions at 2.22, 2.41, 2.63 and 3.00 $\mu$m, respectively, are relatively independent of the astro-chemical model and the gas density distribution when compared against the H$_2$ column density, making them robust tracer of the cosmic-ray ionization rate. Conclusions: We recommend the use of ro-vibrational H$_2$ line emission in combination with estimation of the cloud's H$_2$ column density, to constrain the ionization rate and the spectrum of low energy cosmic-rays. | URI: | http://hdl.handle.net/20.500.12386/34615 | URL: | http://arxiv.org/abs/2206.09780v2 https://www.aanda.org/articles/aa/full_html/2022/08/aa44090-22/aa44090-22.html |
ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361/202244090 | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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File | Description | Size | Format | |
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2206.09780.pdf | postprint | 449.32 kB | Adobe PDF | View/Open |
aa44090-22.pdf | PDF editoriale | 451.33 kB | Adobe PDF | View/Open |
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