H-, He-like recombination spectra III. n-changing collisions in highly-excited Rydberg states and their impact on the radio, IR and optical recombination lines

Guzmán, F. and Chatzikos, M. and van Hoof, P. A. M. and Balser, Dana S. and Dehghanian, M. and Badnell, N. R. and Ferland, G.J. (2019) H-, He-like recombination spectra III. n-changing collisions in highly-excited Rydberg states and their impact on the radio, IR and optical recombination lines. Monthly Notices of the Royal Astronomical Society, 486 (1). 1003–1018. ISSN 0035-8711 (https://doi.org/10.1093/mnras/stz857)

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Abstract

At intermediate to high densities, electron (de-)excitation collisions are the dominant process for populating or depopulating high Rydberg states. In particular, the accurate knowledge of the energy changing (n-changing) collisional rates is determinant for predicting the radio recombination spectra of gaseous nebula. The different data sets present in the literature come either from impact parameter calculations or semi-empirical fits and the rate coefficients agree within a factor of 2. We show in this paper that these uncertainties cause errors lower than 5 per cent in the emission of radio recombination lines of most ionized plasmas of typical nebulae. However, in special circumstances where the transitions between Rydberg levels are amplified by maser effects, the errors can increase up to 20 per cent. We present simulations of the optical depth and Hnα line emission of active galactic nuclei broad-line regions and the Orion Nebula Blister to showcase our findings.

  • Item type:Article
    ID code:67356
    Dates:
    Date
    Event
    1 June 2019
    Published
    27 March 2019
    Published Online
    14 March 2019
    Accepted
    Notes:This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
    Subjects:Science > Physics
    Department:Faculty of Science > Physics
    Depositing user: Pure Administrator
    Date deposited:19 Mar 2019 10:31
    Last modified:09 Apr 2024 00:35
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/67356
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