Cloudy 94 and applications to quasar emission line regions
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| Formato: | Artículo científico |
| Lenguaje: | en |
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Universidad Nacional Autónoma de México
2000
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| _version_ | 1876428784621584384 |
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| author | Gary J. Ferland |
| author_facet | Gary J. Ferland |
| contents | Cloudy 94 and applications to quasar emission line regions Gary J. Ferland Física, Astronomía y Matemáticas LINE FORMATION ATOMIC PROCESSES This review discusses the most recent developments of the plasma simulationcode Cloudy and its application to the emission-line regions of quasars. The long-term goal is to develop the tools needed to determine the chemical compositionof the emitting gas and the luminosity of the central engine for any emission linesource. Emission lines and the underlying thermal continuum are formed in plasmasthat are far from thermodynamic equilibrium. Their thermal and ionization statesare the result of a balance of a vast set of microphysical processes. Once produced,radiation must propagate out of the (usually) optically thick source. No analyticsolutions are possible, and recourse to numerical simulations is necessary. I amdeveloping the large-scale plasma simulation code Cloudy as an investigative tool forthis work, much as an observer might build a spectrometer. This review describesthe current version of Cloudy, version 94. It describes improvements made sincethe release of the previous version, C90 (Ferland et al. 1998).The major recent application has been the development of the \LocallyOptimally-Emitting Cloud" (LOC) model of AGN emission line regions (Baldwinet al. 1995). Powerful selection e ects, introduced by the atomic physics and lineformation process, permit individual lines to form most eciently only near certainselected parameters. These selection e ects, together with the presence of gas witha wide range of conditions, are enough to reproduce the spectrum of a typical quasarwith little dependence on details. The spectrum actually carries little informationto the identity of the emitters. I view this as a major step forward since it providesa method to handle accidental details at the source, so that we can concentrate onessential information such as the luminosity or chemical composition of the quasar. 2000 artículo científico 0185-1101 https://www.redalyc.org/articulo.oa?id=57100938 en http://www.redalyc.org/revista.oa?id=571 Revista Mexicana de Astronomía y Astrofísica application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Astronomía y Astrofísica (México) Vol.9 |
| format | Artículo científico |
| id | redalyc_57100938 |
| institution | Redalyc |
| language | en |
| publishDate | 2000 |
| publisher | Universidad Nacional Autónoma de México |
| spellingShingle | Cloudy 94 and applications to quasar emission line regions Gary J. Ferland Física, Astronomía y Matemáticas LINE FORMATION ATOMIC PROCESSES Cloudy 94 and applications to quasar emission line regions Gary J. Ferland Física, Astronomía y Matemáticas LINE FORMATION ATOMIC PROCESSES This review discusses the most recent developments of the plasma simulationcode Cloudy and its application to the emission-line regions of quasars. The long-term goal is to develop the tools needed to determine the chemical compositionof the emitting gas and the luminosity of the central engine for any emission linesource. Emission lines and the underlying thermal continuum are formed in plasmasthat are far from thermodynamic equilibrium. Their thermal and ionization statesare the result of a balance of a vast set of microphysical processes. Once produced,radiation must propagate out of the (usually) optically thick source. No analyticsolutions are possible, and recourse to numerical simulations is necessary. I amdeveloping the large-scale plasma simulation code Cloudy as an investigative tool forthis work, much as an observer might build a spectrometer. This review describesthe current version of Cloudy, version 94. It describes improvements made sincethe release of the previous version, C90 (Ferland et al. 1998).The major recent application has been the development of the \LocallyOptimally-Emitting Cloud" (LOC) model of AGN emission line regions (Baldwinet al. 1995). Powerful selection e ects, introduced by the atomic physics and lineformation process, permit individual lines to form most eciently only near certainselected parameters. These selection e ects, together with the presence of gas witha wide range of conditions, are enough to reproduce the spectrum of a typical quasarwith little dependence on details. The spectrum actually carries little informationto the identity of the emitters. I view this as a major step forward since it providesa method to handle accidental details at the source, so that we can concentrate onessential information such as the luminosity or chemical composition of the quasar. 2000 artículo científico 0185-1101 https://www.redalyc.org/articulo.oa?id=57100938 en http://www.redalyc.org/revista.oa?id=571 Revista Mexicana de Astronomía y Astrofísica application/pdf Universidad Nacional Autónoma de México Revista Mexicana de Astronomía y Astrofísica (México) Vol.9 |
| title | Cloudy 94 and applications to quasar emission line regions |
| topic | Física, Astronomía y Matemáticas LINE FORMATION ATOMIC PROCESSES |
| url | https://www.redalyc.org/articulo.oa?id=57100938 |