Accurate determination of the freefree Gaunt factor  I. Nonrelativistic Gaunt factors
Abstract
Modern spectral synthesis codes need the thermally averaged freefree Gaunt factor defined over a very wide range of parameter space in order to produce an accurate prediction for the spectrum emitted by an ionized plasma. Until now no set of data exists that would meet this need in a fully satisfactory way. We have therefore undertaken to produce a table of very accurate nonrelativistic Gaunt factors over a much wider range of parameters than has ever been produced before. We first produced a table of nonaveraged Gaunt factors, covering the parameter space ^{10}log ɛ_{i} = 20 to +10 and ^{10}log w = 30 to +25. We then continued to produce a table of thermally averaged Gaunt factors covering the parameter space ^{10}log γ^{2} = 6 to +10 and ^{10}log u = 16 to +13. Finally, we produced a table of the frequency integrated Gaunt factor covering the parameter space ^{10}log γ^{2} = 6 to +10. All the data presented in this paper are available online.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 October 2014
 DOI:
 10.1093/mnras/stu1438
 arXiv:
 arXiv:1407.5048
 Bibcode:
 2014MNRAS.444..420V
 Keywords:

 atomic data;
 plasmas;
 radiation mechanisms: thermal;
 ISM: general;
 radio continuum: general;
 Astrophysics  High Energy Astrophysical Phenomena;
 Physics  Accelerator Physics;
 Physics  Atomic Physics;
 Physics  Plasma Physics;
 Physics  Space Physics
 EPrint:
 10 pages, 5 tables, 3 figures. Fixed typo in Eq. 14