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

F. Guzmán, M. Chatzikos, P. A.M. Van Hoof, Dana S. Balser, M. Dehghanian, N. R. Badnell, G. J. Ferland

Research output: Contribution to journalArticlepeer-review

8 Scopus citations

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.

Original languageEnglish
Pages (from-to)1003-1018
Number of pages16
JournalMonthly Notices of the Royal Astronomical Society
Volume486
Issue number1
DOIs
StatePublished - Jun 11 2019

Bibliographical note

Funding Information:
The authors acknowledge support from the National Science Foundation (AST-1816537) and NASA ATP program (grant number 17-ATP17-0141). MC acknowledges support from Space Telescope Science Institute (STScI) (HST-AR-14286.001-A and HSTAR- 14556.001-A). PvH acknowledges support from the Belgian Science Policy Office through contract no. BR/143/A2/BRASS. NRBacknowledges support from Science and Technology Facilities Council (STFC) (UK) through the University of Strathclyde APAP Network grant ST/R000743/1. MD and GF acknowledge support from the National Science Foundation (NSF) (AST-1816537), NASA (ATP 17-0141), and STScI (HST-AR-13914, HST-AR-15018). The National Radio Astronomy Observatory is a Facility of the Nacional Science Foundation operated under cooperative agreement by Associated University, Inc.

Funding Information:
The authors acknowledge support from the National Science Foundation (AST-1816537) and NASA ATP program (grant number 17-ATP17-0141). MC acknowledges support from Space Telescope Science Institute (STScI) (HST-AR-14286.001-A and HST-AR-14556.001-A). PvH acknowledges support from the Belgian Science Policy Office through contract no. BR/143/A2/BRASS. NRB acknowledges support from Science and Technology Facilities Council ( STFC) (UK) through the University of Strathclyde APAP Network grant ST/R000743/1. MD and GF acknowledge support from the National Science Foundation (NSF) (AST-1816537), NASA (ATP 17-0141), and STScI (HST-AR-13914, HST-AR-15018). The National Radio Astronomy Observatory is a Facility of the Nacional Science Foundation operated under cooperative agreement by Associated University, Inc.

Publisher Copyright:
© 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society.

Keywords

  • H II regions
  • atomic data
  • atomic processes
  • masers
  • radio lines: general
  • submillimetre: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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