Accurate determination of the free-free Gaunt factor - II. Relativistic Gaunt factors

P. A.M. Van Hoof; G. J. Ferland; R. J.R. Williams; K. Volk; M. Chatzikos; M. Lykins; R. L. Porter

doi:10.1093/mnras/stv404

Accurate determination of the free-free Gaunt factor - II. Relativistic Gaunt factors

P. A.M. Van Hoof, G. J. Ferland, R. J.R. Williams, K. Volk, M. Chatzikos, M. Lykins, R. L. Porter

Research output: Contribution to journal › Article › peer-review

17 Scopus citations

Abstract

When modelling an ionized plasma, all spectral synthesis codes need the thermally averaged free-free Gaunt factor defined over a very wide range of parameter space in order to produce an accurate prediction for the spectrum. Until now no data set exists that would meet these needs completely.We have therefore produced a table of relativistic Gaunt factors over a much wider range of parameter space than has ever been produced before. We present tables of the thermally averaged Gaunt factor covering the range ¹⁰log γ ² = -6 to 10 and ¹⁰log u = -16 to 13 for all atomic numbers Z = 1 through 36. The data were calculated using the relativistic Bethe-Heitler-Elwert (BHE) approximation and were subsequently merged with accurate non-relativistic results in those parts of the parameter space where the BHE approximation is not valid. These data will be incorporated in the next major release of the spectral synthesis code CLOUDY. We also produced tables of the frequency integrated Gaunt factor covering the parameter space ¹⁰log γ² = -6 to +10 for all values of Z between 1 and 36. All the data presented in this paper are available online.

Original language	English
Pages (from-to)	2112-2118
Number of pages	7
Journal	Monthly Notices of the Royal Astronomical Society
Volume	449
Issue number	2
DOIs	https://doi.org/10.1093/mnras/stv404
State	Published - May 11 2015

Bibliographical note

Publisher Copyright:
© 2015 The Authors.

Funding

PAMvH acknowledges support from the Belgian Science Policy Office through the ESA PRODEX program. GJF acknowledges support by NSF (1108928, 1109061, and 1412155), NASA (10-ATP10-0053, 10-ADAP10-0073, NNX12AH73G, and ATP13-0153), and STScI (HST-AR-13245, GO-12560, HST-GO-12309, and GO-13310.002-A).

Funders	Funder number
National Science Foundation (NSF)
Directorate for Mathematical and Physical Sciences	1108928, 1412155, 1109061
National Aeronautics and Space Administration	10-ADAP10-0073, NNX12AH73G, 10-ATP10-0053, ATP13-0153
National Sleep Foundation
Space Telescope Science Institute	HST-AR-13245, GO-13310.002-A, GO-12560, HST-GO-12309
Belgian Federal Science Policy Office
European Society of Anaesthesiology

Keywords

Atomic data
ISM: general
Plasmas
Radiation mechanisms: thermal
Radio continuum: general
Relativistic processes

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

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10.1093/mnras/stv404

Cite this

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title = "Accurate determination of the free-free Gaunt factor - II. Relativistic Gaunt factors",

abstract = "When modelling an ionized plasma, all spectral synthesis codes need the thermally averaged free-free Gaunt factor defined over a very wide range of parameter space in order to produce an accurate prediction for the spectrum. Until now no data set exists that would meet these needs completely.We have therefore produced a table of relativistic Gaunt factors over a much wider range of parameter space than has ever been produced before. We present tables of the thermally averaged Gaunt factor covering the range 10log γ 2 = -6 to 10 and 10log u = -16 to 13 for all atomic numbers Z = 1 through 36. The data were calculated using the relativistic Bethe-Heitler-Elwert (BHE) approximation and were subsequently merged with accurate non-relativistic results in those parts of the parameter space where the BHE approximation is not valid. These data will be incorporated in the next major release of the spectral synthesis code CLOUDY. We also produced tables of the frequency integrated Gaunt factor covering the parameter space 10log γ2 = -6 to +10 for all values of Z between 1 and 36. All the data presented in this paper are available online.",

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author = "{Van Hoof}, {P. A.M.} and Ferland, {G. J.} and Williams, {R. J.R.} and K. Volk and M. Chatzikos and M. Lykins and Porter, {R. L.}",

note = "Publisher Copyright: {\textcopyright} 2015 The Authors.",

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doi = "10.1093/mnras/stv404",

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AU - Ferland, G. J.

AU - Williams, R. J.R.

AU - Volk, K.

AU - Chatzikos, M.

AU - Lykins, M.

AU - Porter, R. L.

PY - 2015/5/11

Y1 - 2015/5/11

N2 - When modelling an ionized plasma, all spectral synthesis codes need the thermally averaged free-free Gaunt factor defined over a very wide range of parameter space in order to produce an accurate prediction for the spectrum. Until now no data set exists that would meet these needs completely.We have therefore produced a table of relativistic Gaunt factors over a much wider range of parameter space than has ever been produced before. We present tables of the thermally averaged Gaunt factor covering the range 10log γ 2 = -6 to 10 and 10log u = -16 to 13 for all atomic numbers Z = 1 through 36. The data were calculated using the relativistic Bethe-Heitler-Elwert (BHE) approximation and were subsequently merged with accurate non-relativistic results in those parts of the parameter space where the BHE approximation is not valid. These data will be incorporated in the next major release of the spectral synthesis code CLOUDY. We also produced tables of the frequency integrated Gaunt factor covering the parameter space 10log γ2 = -6 to +10 for all values of Z between 1 and 36. All the data presented in this paper are available online.

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KW - Radio continuum: general

KW - Relativistic processes

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Accurate determination of the free-free Gaunt factor - II. Relativistic Gaunt factors

Abstract

Bibliographical note

Funding

Keywords

ASJC Scopus subject areas

Access to Document

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