Bias versus variance when fitting multi-species molecular lines with a non-LTE radiative transfer model
ROUEFF, Antoine
Institut des Matériaux, de Microélectronique et des Nanosciences de Provence [IM2NP]
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Institut des Matériaux, de Microélectronique et des Nanosciences de Provence [IM2NP]
ROUEFF, Antoine
Institut des Matériaux, de Microélectronique et des Nanosciences de Provence [IM2NP]
Institut des Matériaux, de Microélectronique et des Nanosciences de Provence [IM2NP]
SÉGAL, Léontine
Institut de RadioAstronomie Millimétrique [IRAM]
Institut des Matériaux, de Microélectronique et des Nanosciences de Provence [IM2NP]
Institut de RadioAstronomie Millimétrique [IRAM]
Institut des Matériaux, de Microélectronique et des Nanosciences de Provence [IM2NP]
EINIG, Lucas
Institut de RadioAstronomie Millimétrique [IRAM]
GIPSA - Signal Images Physique [GIPSA-SIGMAPHY]
Institut de RadioAstronomie Millimétrique [IRAM]
GIPSA - Signal Images Physique [GIPSA-SIGMAPHY]
PALUD, Pierre
Centre de Recherche en Informatique, Signal et Automatique de Lille - UMR 9189 [CRIStAL]
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]
Centre de Recherche en Informatique, Signal et Automatique de Lille - UMR 9189 [CRIStAL]
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]
BRON, Emeric
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 d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
CHAINAIS, Pierre
Centre de Recherche en Informatique, Signal et Automatique de Lille - UMR 9189 [CRIStAL]
Centre de Recherche en Informatique, Signal et Automatique de Lille - UMR 9189 [CRIStAL]
COUDÉ, Simon
Worcester State University [Worcester]
Harvard-Smithsonian Center for Astrophysics [CfA]
Worcester State University [Worcester]
Harvard-Smithsonian Center for Astrophysics [CfA]
LANGUIGNON, David
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 d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
BOURLOT, Jacques Le
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 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 PETIT, Franck
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 d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
ROUEFF, Evelyne
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 d'Etude du Rayonnement et de la Matière en Astrophysique et Atmosphères = Laboratory for Studies of Radiation and Matter in Astrophysics and Atmospheres [LERMA]
THOUVENIN, Pierre-Antoine
Centre de Recherche en Informatique, Signal et Automatique de Lille - UMR 9189 [CRIStAL]
< Leer menos
Centre de Recherche en Informatique, Signal et Automatique de Lille - UMR 9189 [CRIStAL]
Idioma
en
Article de revue
Este ítem está publicado en
Astronomy and Astrophysics - A&A. 2024-06, vol. 686, n° June, p. A255
EDP Sciences
Resumen en inglés
Robust radiative transfer techniques are requisite for efficiently extracting the physical and chemical information from molecular rotational lines.We study several hypotheses that enable robust estimations of the column ...Leer más >
Robust radiative transfer techniques are requisite for efficiently extracting the physical and chemical information from molecular rotational lines.We study several hypotheses that enable robust estimations of the column densities and physical conditions when fitting one or two transitions per molecular species. We study the extent to which simplifying assumptions aimed at reducing the complexity of the problem introduce estimation biases and how to detect them.We focus on the CO and HCO+ isotopologues and analyze maps of a 50 square arcminutes field. We used the RADEX escape probability model to solve the statistical equilibrium equations and compute the emerging line profiles, assuming that all species coexist. Depending on the considered set of species, we also fixed the abundance ratio between some species and explored different values. We proposed a maximum likelihood estimator to infer the physical conditions and considered the effect of both the thermal noise and calibration uncertainty. We analyzed any potential biases induced by model misspecifications by comparing the results on the actual data for several sets of species and confirmed with Monte Carlo simulations. The variance of the estimations and the efficiency of the estimator were studied based on the Cramér-Rao lower bound.Column densities can be estimated with 30% accuracy, while the best estimations of the volume density are found to be within a factor of two. Under the chosen model framework, the peak 12CO(1−0) is useful for constraining the kinetic temperature. The thermal pressure is better and more robustly estimated than the volume density and kinetic temperature separately. Analyzing CO and HCO+ isotopologues and fitting the full line profile are recommended practices with respect to detecting possible biases.Combining a non-local thermodynamic equilibrium model with a rigorous analysis of the accuracy allows us to obtain an efficient estimator and identify where the model is misspecified. We note that other combinations of molecular lines could be studied in the future.< Leer menos
Palabras clave en inglés
ISM: molecules
ISM: clouds
Radiative transfer
Methods: data analysis
Methods: statistical
Orígen
Importado de HalCentros de investigación