Testing SALT Approximations with Numerical Radiation Transfer Code. I. Validity and Applicability
Absorption line spectroscopy offers one of the best opportunities to constrain the properties of galactic outflows and the environment of the circumgalactic medium. Extracting physical information from line profiles is difficult; however, for the physics governing the underlying radiation transfer i...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/acd331 |
| _version_ | 1797698393206685696 |
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| author | C. Carr L. Michel-Dansac J. Blaizot C. Scarlata A. Henry A. Verhamme |
| author_facet | C. Carr L. Michel-Dansac J. Blaizot C. Scarlata A. Henry A. Verhamme |
| author_sort | C. Carr |
| collection | DOAJ |
| description | Absorption line spectroscopy offers one of the best opportunities to constrain the properties of galactic outflows and the environment of the circumgalactic medium. Extracting physical information from line profiles is difficult; however, for the physics governing the underlying radiation transfer is complicated and depends on many different parameters. Idealized analytical models are necessary to constrain the large parameter spaces efficiently, but are typically plagued by model degeneracy and systematic errors. Comparison tests with idealized numerical radiation transfer codes offer an excellent opportunity to confront both of these issues. In this paper, we present a detailed comparison between SALT, an analytical radiation transfer model for predicting UV spectra of galactic outflows, with the numerical radiation transfer software, RASCAS. Our analysis has led to upgrades to both models including an improved derivation of SALT and a customizable adaptive mesh refinement routine for RASCAS. We explore how well SALT, when paired with a Monte Carlo fitting procedure, can recover flow parameters from nonturbulent and turbulent flows. Overall we find that turbulence leads to biases in the recovery of kinematic parameters and the optical depth, but find that derived quantities (e.g., mass outflow rates, column density, etc.) are still well recovered. From the analysis, we estimate average uncertainties in our ability to measure metal flow rates spanning 0.65 (0.95) dex in M _⊙ yr ^−1 and uncertainties spanning 0.54 (0.94) dex in cm ^−2 for column densities at a resolution of 20 (100) km s ^−1 and signal-to-noise ratio = 10. |
| first_indexed | 2024-03-12T03:53:25Z |
| format | Article |
| id | doaj.art-50cd626e655a4cd09e28e7e19cc8c018 |
| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T03:53:25Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal |
| spelling | doaj.art-50cd626e655a4cd09e28e7e19cc8c0182023-09-03T12:08:15ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0195218810.3847/1538-4357/acd331Testing SALT Approximations with Numerical Radiation Transfer Code. I. Validity and ApplicabilityC. Carr0https://orcid.org/0000-0003-4166-2855L. Michel-Dansac1J. Blaizot2C. Scarlata3https://orcid.org/0000-0002-9136-8876A. Henry4https://orcid.org/0000-0002-6586-4446A. Verhamme5https://orcid.org/0000-0002-2201-1865Minnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota , 316 Church St. SE, Minneapolis, MN 55455, USA ; CodyCarr24@gmail.comUniv Lyon, Univ Lyon1, ENS de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574 , F-69230 Saint-Genis-Laval, FranceUniv Lyon, Univ Lyon1, ENS de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574 , F-69230 Saint-Genis-Laval, FranceMinnesota Institute for Astrophysics, School of Physics and Astronomy, University of Minnesota , 316 Church St. SE, Minneapolis, MN 55455, USA ; CodyCarr24@gmail.comSpace Telescope Science Institute , 3700 San Martin Dr., Baltimore, MD 21218, USA ;Univ Lyon, Univ Lyon1, ENS de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon UMR5574 , F-69230 Saint-Genis-Laval, France; Observatoire de Genève, Université de Genève , 51 Ch. des Maillettes, 1290 Versoix, SwitzerlandAbsorption line spectroscopy offers one of the best opportunities to constrain the properties of galactic outflows and the environment of the circumgalactic medium. Extracting physical information from line profiles is difficult; however, for the physics governing the underlying radiation transfer is complicated and depends on many different parameters. Idealized analytical models are necessary to constrain the large parameter spaces efficiently, but are typically plagued by model degeneracy and systematic errors. Comparison tests with idealized numerical radiation transfer codes offer an excellent opportunity to confront both of these issues. In this paper, we present a detailed comparison between SALT, an analytical radiation transfer model for predicting UV spectra of galactic outflows, with the numerical radiation transfer software, RASCAS. Our analysis has led to upgrades to both models including an improved derivation of SALT and a customizable adaptive mesh refinement routine for RASCAS. We explore how well SALT, when paired with a Monte Carlo fitting procedure, can recover flow parameters from nonturbulent and turbulent flows. Overall we find that turbulence leads to biases in the recovery of kinematic parameters and the optical depth, but find that derived quantities (e.g., mass outflow rates, column density, etc.) are still well recovered. From the analysis, we estimate average uncertainties in our ability to measure metal flow rates spanning 0.65 (0.95) dex in M _⊙ yr ^−1 and uncertainties spanning 0.54 (0.94) dex in cm ^−2 for column densities at a resolution of 20 (100) km s ^−1 and signal-to-noise ratio = 10.https://doi.org/10.3847/1538-4357/acd331Interstellar absorptionCircumgalactic mediumGalactic windsRadiative transfer simulationsRadiative transferMonte Carlo methods |
| spellingShingle | C. Carr L. Michel-Dansac J. Blaizot C. Scarlata A. Henry A. Verhamme Testing SALT Approximations with Numerical Radiation Transfer Code. I. Validity and Applicability The Astrophysical Journal Interstellar absorption Circumgalactic medium Galactic winds Radiative transfer simulations Radiative transfer Monte Carlo methods |
| title | Testing SALT Approximations with Numerical Radiation Transfer Code. I. Validity and Applicability |
| title_full | Testing SALT Approximations with Numerical Radiation Transfer Code. I. Validity and Applicability |
| title_fullStr | Testing SALT Approximations with Numerical Radiation Transfer Code. I. Validity and Applicability |
| title_full_unstemmed | Testing SALT Approximations with Numerical Radiation Transfer Code. I. Validity and Applicability |
| title_short | Testing SALT Approximations with Numerical Radiation Transfer Code. I. Validity and Applicability |
| title_sort | testing salt approximations with numerical radiation transfer code i validity and applicability |
| topic | Interstellar absorption Circumgalactic medium Galactic winds Radiative transfer simulations Radiative transfer Monte Carlo methods |
| url | https://doi.org/10.3847/1538-4357/acd331 |
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