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| Main Authors: | , , , , , , , , , |
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| Format: | Preprint |
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2024
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2401.09975 |
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| _version_ | 1866917570155642880 |
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| author | Muller, S. Gal, R. Le Roueff, E. Black, J. H. Faure, A. Guelin, M. Omont, A. Gerin, M. Combes, F. Aalto, S. |
| author_facet | Muller, S. Gal, R. Le Roueff, E. Black, J. H. Faure, A. Guelin, M. Omont, A. Gerin, M. Combes, F. Aalto, S. |
| contents | We report the first interstellar identification of protonated acetylene, C2H3+, a fundamental hydrocarbon, in the z=0.89 molecular absorber toward the gravitationally lensed quasar PKS1830-211. The molecular species is identified from clear absorption features corresponding to the 2_12-1_01 (rest frequency 494.034 GHz) and 1_11-0_00 (431.316 GHz) ground-state transitions of ortho and para forms of C2H3+, respectively, in ALMA spectra toward the southwestern image of PKS1830-211, where numerous molecules, including other hydrocarbons, have already been detected. From the simple assumption of local thermodynamic equilibrium (LTE) with cosmic microwave background photons and an ortho-to-para ratio of three, we estimate a total C2H3+ column density of 2 x 10^12 cm^-2 and an abundance of 10^-10 compared to H_2. However, formation pumping could affect the population of metastable states, yielding a C2H3+ column density higher than the LTE value by a factor of a few. We explore possible routes to the formation of C2H3+, mainly connected to acetylene and methane, and find that the methane route is more likely in PDR environment. As one of the initial hydrocarbon building blocks, C2H3+ is thought to play an important role in astrochemistry, in particular in the formation of more complex organic molecules. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2401_09975 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Protonated acetylene in the z=0.89 molecular absorber toward PKS1830-211 Muller, S. Gal, R. Le Roueff, E. Black, J. H. Faure, A. Guelin, M. Omont, A. Gerin, M. Combes, F. Aalto, S. Astrophysics of Galaxies We report the first interstellar identification of protonated acetylene, C2H3+, a fundamental hydrocarbon, in the z=0.89 molecular absorber toward the gravitationally lensed quasar PKS1830-211. The molecular species is identified from clear absorption features corresponding to the 2_12-1_01 (rest frequency 494.034 GHz) and 1_11-0_00 (431.316 GHz) ground-state transitions of ortho and para forms of C2H3+, respectively, in ALMA spectra toward the southwestern image of PKS1830-211, where numerous molecules, including other hydrocarbons, have already been detected. From the simple assumption of local thermodynamic equilibrium (LTE) with cosmic microwave background photons and an ortho-to-para ratio of three, we estimate a total C2H3+ column density of 2 x 10^12 cm^-2 and an abundance of 10^-10 compared to H_2. However, formation pumping could affect the population of metastable states, yielding a C2H3+ column density higher than the LTE value by a factor of a few. We explore possible routes to the formation of C2H3+, mainly connected to acetylene and methane, and find that the methane route is more likely in PDR environment. As one of the initial hydrocarbon building blocks, C2H3+ is thought to play an important role in astrochemistry, in particular in the formation of more complex organic molecules. |
| title | Protonated acetylene in the z=0.89 molecular absorber toward PKS1830-211 |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2401.09975 |