C18O, 13CO, and 12CO abundances and excitation temperatures in the Orion B molecular cloud
Analysis of the achievable precision in modeling spectral lines within the approximation of the local thermodynamic equilibrium
Type de document :
Compte-rendu et recension critique d'ouvrage
Titre :
C18O, 13CO, and 12CO abundances and excitation temperatures in the Orion B molecular cloud
Analysis of the achievable precision in modeling spectral lines within the approximation of the local thermodynamic equilibrium
Analysis of the achievable precision in modeling spectral lines within the approximation of the local thermodynamic equilibrium
Auteur(s) :
Roueff, Antoine [Auteur correspondant]
PhyTI [PhyTI]
Gerin, Maryvonne [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Gratier, Pierre [Auteur]
FORMATION STELLAIRE 2020
Levrier, François [Auteur]
Astrophysique
Pety, Jérôme [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Gaudel, Mathilde [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Goicoechea, Javier [Auteur]
Instituto de Física Fundamental [Madrid] [IFF]
Orkisz, Jan [Auteur]
Onsala Space Observatory [OSO]
de Souza Magalhaes, Victor [Auteur]
Institut de RadioAstronomie Millimétrique [IRAM]
Vono, Maxime [Auteur]
Signal et Communications [IRIT-SC]
Bardeau, Sébastien [Auteur]
Institut de RadioAstronomie Millimétrique [IRAM]
Bron, Emeric [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Chanussot, Jocelyn [Auteur]
GIPSA - Signal Images Physique [GIPSA-SIGMAPHY]
Chainais, Pierre [Auteur]
Centre de Recherche en Informatique, Signal et Automatique de Lille - UMR 9189 [CRIStAL]
Guzman, Viviana V. [Auteur]
Pontificia Universidad Católica de Chile [UC]
Hughes, Annie [Auteur]
Institut de recherche en astrophysique et planétologie [IRAP]
Kainulainen, Jouni [Auteur]
Onsala Space Observatory [OSO]
Languignon, David [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Le Bourlot, Jacques [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Laboratoire Univers et Théories [LUTH (UMR_8102)]
Le Petit, Franck [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Laboratoire Univers et Théories [LUTH (UMR_8102)]
Liszt, Harvey S. [Auteur]
National Radio Astronomy Observatory [Charlottesville] [NRAO]
Marchal, Antoine [Auteur]
Canadian Institute for Theoretical Astrophysics [CITA]
Miville-Deschênes, Marc-Antoine [Auteur]
Astrophysique Interprétation Modélisation [AIM (UMR_7158 / UMR_E_9005 / UM_112)]
Peretto, Nicolas [Auteur]
Cardiff University
Roueff, Evelyne [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Sievers, Albrecht [Auteur]
Institut de RadioAstronomie Millimétrique [IRAM]
PhyTI [PhyTI]
Gerin, Maryvonne [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Gratier, Pierre [Auteur]
FORMATION STELLAIRE 2020
Levrier, François [Auteur]
Astrophysique
Pety, Jérôme [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Gaudel, Mathilde [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Goicoechea, Javier [Auteur]
Instituto de Física Fundamental [Madrid] [IFF]
Orkisz, Jan [Auteur]
Onsala Space Observatory [OSO]
de Souza Magalhaes, Victor [Auteur]
Institut de RadioAstronomie Millimétrique [IRAM]
Vono, Maxime [Auteur]
Signal et Communications [IRIT-SC]
Bardeau, Sébastien [Auteur]
Institut de RadioAstronomie Millimétrique [IRAM]
Bron, Emeric [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Chanussot, Jocelyn [Auteur]
GIPSA - Signal Images Physique [GIPSA-SIGMAPHY]
Chainais, Pierre [Auteur]
Centre de Recherche en Informatique, Signal et Automatique de Lille - UMR 9189 [CRIStAL]
Guzman, Viviana V. [Auteur]
Pontificia Universidad Católica de Chile [UC]
Hughes, Annie [Auteur]
Institut de recherche en astrophysique et planétologie [IRAP]
Kainulainen, Jouni [Auteur]
Onsala Space Observatory [OSO]
Languignon, David [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Le Bourlot, Jacques [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Laboratoire Univers et Théories [LUTH (UMR_8102)]
Le Petit, Franck [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Laboratoire Univers et Théories [LUTH (UMR_8102)]
Liszt, Harvey S. [Auteur]
National Radio Astronomy Observatory [Charlottesville] [NRAO]
Marchal, Antoine [Auteur]
Canadian Institute for Theoretical Astrophysics [CITA]
Miville-Deschênes, Marc-Antoine [Auteur]
Astrophysique Interprétation Modélisation [AIM (UMR_7158 / UMR_E_9005 / UM_112)]
Peretto, Nicolas [Auteur]
Cardiff University
Roueff, Evelyne [Auteur]
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
Sievers, Albrecht [Auteur]
Institut de RadioAstronomie Millimétrique [IRAM]
Titre de la revue :
Astronomy and Astrophysics - A&A
Éditeur :
EDP Sciences
Date de publication :
2021-01
ISSN :
0004-6361
Mot(s)-clé(s) en anglais :
ISM: molecules
ISM: clouds
radiative transfer
methods: data analysis
methods: statistical
ISM: clouds
radiative transfer
methods: data analysis
methods: statistical
Discipline(s) HAL :
Physique [physics]/Astrophysique [astro-ph]
Informatique [cs]
Informatique [cs]
Résumé en anglais : [en]
Context. CO isotopologue transitions are routinely observed in molecular clouds for the purpose of probing the column density of the gas and the elemental ratios of carbon and oxygen, in addition to tracing the kinematics ...
Lire la suite >Context. CO isotopologue transitions are routinely observed in molecular clouds for the purpose of probing the column density of the gas and the elemental ratios of carbon and oxygen, in addition to tracing the kinematics of the environment.Aims. Our study is aimed at estimating the abundances, excitation temperatures, velocity field, and velocity dispersions of the three main CO isotopologues towards a subset of the Orion B molecular cloud, which includes IC 434, NGC 2023, and the Horsehead pillar.Methods. We used the Cramer Rao bound (CRB) technique to analyze and estimate the precision of the physical parameters in the framework of local-thermodynamic-equilibrium (LTE) excitation and radiative transfer with added white Gaussian noise. We propose a maximum likelihood estimator to infer the physical conditions from the 1–0 and 2–1 transitions of CO isotopologues. Simulations show that this estimator is unbiased and proves efficient for a common range of excitation temperatures and column densities (Tex > 6 K, N > 1014−1015 cm−2).Results. Contrary to general assumptions, the various CO isotopologues have distinct excitation temperatures and the line intensity ratios between different isotopologues do not accurately reflect the column density ratios. We find mean fractional abundances that are consistent with previous determinations towards other molecular clouds. However, significant local deviations are inferred, not only in regions exposed to the UV radiation field, but also in shielded regions. These deviations result from the competition between selective photodissociation, chemical fractionation, and depletion on grain surfaces. We observe that the velocity dispersion of the C18O emission is 10% smaller than that of 13CO. The substantial gain resulting from the simultaneous analysis of two different rotational transitions of the same species is rigorously quantified.Conclusions. The CRB technique is a promising avenue for analyzing the estimation of physical parameters from the fit of spectral lines. Future works will generalize its application to non-LTE excitation and radiative transfer methods.Lire moins >
Lire la suite >Context. CO isotopologue transitions are routinely observed in molecular clouds for the purpose of probing the column density of the gas and the elemental ratios of carbon and oxygen, in addition to tracing the kinematics of the environment.Aims. Our study is aimed at estimating the abundances, excitation temperatures, velocity field, and velocity dispersions of the three main CO isotopologues towards a subset of the Orion B molecular cloud, which includes IC 434, NGC 2023, and the Horsehead pillar.Methods. We used the Cramer Rao bound (CRB) technique to analyze and estimate the precision of the physical parameters in the framework of local-thermodynamic-equilibrium (LTE) excitation and radiative transfer with added white Gaussian noise. We propose a maximum likelihood estimator to infer the physical conditions from the 1–0 and 2–1 transitions of CO isotopologues. Simulations show that this estimator is unbiased and proves efficient for a common range of excitation temperatures and column densities (Tex > 6 K, N > 1014−1015 cm−2).Results. Contrary to general assumptions, the various CO isotopologues have distinct excitation temperatures and the line intensity ratios between different isotopologues do not accurately reflect the column density ratios. We find mean fractional abundances that are consistent with previous determinations towards other molecular clouds. However, significant local deviations are inferred, not only in regions exposed to the UV radiation field, but also in shielded regions. These deviations result from the competition between selective photodissociation, chemical fractionation, and depletion on grain surfaces. We observe that the velocity dispersion of the C18O emission is 10% smaller than that of 13CO. The substantial gain resulting from the simultaneous analysis of two different rotational transitions of the same species is rigorously quantified.Conclusions. The CRB technique is a promising avenue for analyzing the estimation of physical parameters from the fit of spectral lines. Future works will generalize its application to non-LTE excitation and radiative transfer methods.Lire moins >
Langue :
Anglais
Vulgarisation :
Non
Projet ANR :
Collections :
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- https://hal.archives-ouvertes.fr/hal-02570214v2/document
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- http://arxiv.org/pdf/2005.08317
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- https://hal.archives-ouvertes.fr/hal-02570214v2/document
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- https://hal.archives-ouvertes.fr/hal-02570214v2/document
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- https://hal.archives-ouvertes.fr/hal-02570214v2/document
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- aa37776-20.pdf
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- 2005.08317
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