Testing atomic collision theory with the two-photon continuum of astrophysical nebulae

F. Guzmán; N. R. Badnell; M.  Chatzikos; P. A. M. van Hoof; R. J. R. Williams; G. J. Ferland

doi:10.1093/mnras/stx269

Testing atomic collision theory with the two-photon continuum of astrophysical nebulae

F. Guzmán, N. R. Badnell, M. Chatzikos, P. A. M. van Hoof, R. J. R. Williams, G. J. Ferland

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Abstract

Accurate rates for energy-degenerate l-changing collisions are needed to determine cosmological abundances and recombination. There are now several competing theories for the treatment of this process, and it is not possible to test these experimentally. We show that the H i two-photon continuum produced by astrophysical nebulae is strongly affected by l-changing collisions. We perform an analysis of the different underlying atomic processes and simulate the recombination and two-photon spectrum of a nebula containing H and He. We provide an extended set of effective recombination coefficients and updated l-changing 2s − 2p transition rates using several competing theories. In principle, accurate astronomical observations could determine which theory is correct.

Original language	English
Journal	Monthly Notices of the Royal Astronomical Society
Early online date	1 Feb 2017
DOIs	https://doi.org/10.1093/mnras/stx269
Publication status	E-pub ahead of print - 1 Feb 2017

Keywords

cosmology
cosmic background
cosmic observations
atomic data
atomic processes
H ii regions
planetary nebulae

Access to Document

10.1093/mnras/stx269

Guzman-etal-MNRAS2017-Testing-atomic-collision-theoryAccepted author manuscript, 218 KB

https://academic.oup.com/mnras

Cite this

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title = "Testing atomic collision theory with the two-photon continuum of astrophysical nebulae",

abstract = "Accurate rates for energy-degenerate l-changing collisions are needed to determine cosmological abundances and recombination. There are now several competing theories for the treatment of this process, and it is not possible to test these experimentally. We show that the H i two-photon continuum produced by astrophysical nebulae is strongly affected by l-changing collisions. We perform an analysis of the different underlying atomic processes and simulate the recombination and two-photon spectrum of a nebula containing H and He. We provide an extended set of effective recombination coefficients and updated l-changing 2s − 2p transition rates using several competing theories. In principle, accurate astronomical observations could determine which theory is correct.",

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T1 - Testing atomic collision theory with the two-photon continuum of astrophysical nebulae

AU - Guzmán, F.

AU - Badnell, N. R.

AU - Chatzikos, M.

AU - van Hoof, P. A. M.

AU - Williams, R. J. R.

AU - Ferland, G. J.

N1 - This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record F. Guzmán, N. R. Badnell, M. Chatzikos, P. A. M. van Hoof, R.J.R. Williams, G.J. Ferland.; Testing atomic collision theory with the two-photon continuum of astrophysical nebulae. Mon Not R Astron Soc 2017 stx269. doi: 10.1093/mnras/stx269 is available online at: https://dx.doi.org/10.1093/mnras/stx269

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AB - Accurate rates for energy-degenerate l-changing collisions are needed to determine cosmological abundances and recombination. There are now several competing theories for the treatment of this process, and it is not possible to test these experimentally. We show that the H i two-photon continuum produced by astrophysical nebulae is strongly affected by l-changing collisions. We perform an analysis of the different underlying atomic processes and simulate the recombination and two-photon spectrum of a nebula containing H and He. We provide an extended set of effective recombination coefficients and updated l-changing 2s − 2p transition rates using several competing theories. In principle, accurate astronomical observations could determine which theory is correct.

KW - cosmology

KW - cosmic background

KW - cosmic observations

KW - atomic data

KW - atomic processes

KW - H ii regions

KW - planetary nebulae

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