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

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

5 Scopus citations

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 lchanging 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
Pages (from-to)	3944-3950
Number of pages	7
Journal	Monthly Notices of the Royal Astronomical Society
Volume	467
Issue number	4
DOIs	https://doi.org/10.1093/mnras/stx269
State	Published - Jun 1 2017

Bibliographical note

Publisher Copyright:
© 2017 The Authors.

Funding

The authors acknowledge Prof J. Chluba for pointing out the importance of atomic data on CRR simulations. We acknowledge 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, GO-13310.002-A, HST-AR-13914 and HST-AR-14286.001). MC has been supported by STScI (HST-AR-14286.001-A). PvH was funded by the Belgian Science Policy Office under contract no. BR/154/PI/MOLPLAN.

Funders	Funder number
Science and Technology Facilities Council	ST/J000892/1
U.S. Department of Energy Chinese Academy of Sciences Guangzhou Municipal Science and Technology Project Oak Ridge National Laboratory Extreme Science and Engineering Discovery Environment National Science Foundation National Energy Research Scientific Computing Center National Natural Science Foundation of China	1108928, 1412155, 1109061
Belgian Federal Science Policy Office	BR/154/PI/MOLPLAN
National Aeronautics and Space Administration	NNX12AH73G, 10-ADAP10-0073, 10-ATP10-0053, ATP13-0153
Space Telescope Science Institute	HST-AR-14286.001, HST-AR-13245, GO-13310.002-A, HST-AR-14286.001-A, HST-GO-12309, GO-12560, HST-AR-13914

Keywords

Atomic data
Atomic processes
Cosmic background radiation
Cosmology: observations
H II regions
Planetary nebulae: general

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.1093/mnras/stx269

Cite this

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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 lchanging 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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AU - Badnell, N. R.

AU - Chatzikos, M.

AU - Van Hoof, P. A.M.

AU - Williams, R. J.R.

AU - Ferland, G. J.

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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 lchanging 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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KW - Atomic processes

KW - Cosmic background radiation

KW - Cosmology: observations

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

Abstract

Bibliographical note

Funding

Keywords

ASJC Scopus subject areas

Access to Document

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