Temperature-averaged and total free-free Gaunt factors for $\kappa$ and Maxwellian distributions of electrons

Abstract

Aims. Optically thin plasmas may deviate from thermal equilibrium and thus, electrons (and ions) are no longer described by the Maxwellian distribution. Instead they can be described by $\kappa$-distributions. The free-free spectrum and radiative losses depend on the temperature-averaged (over the electrons distribution) and total Gaunt factors, respectively. Thus, there is a need to calculate and make available these factors to be used by any software that deals with plasma emission. Methods. We recalculated the free-free Gaunt factor for a wide range of energies and frequencies using hypergeometric functions of complex arguments and the Clenshaw recurrence formula technique combined with approximations whenever the difference between the initial and final electron energies is smaller than $10^{-10}$ in units of $z^{2}Ry$. We used double and quadruple precisions. The temperature- averaged and total Gaunt factors calculations make use of the Gauss-Laguerre integration with 128 nodes. Results. The temperature-averaged and total Gaunt factors depend on the $\kappa$ parameter, which shows increasing deviations (with respect to the results obtained with the use of the Maxwellian distribution) with decreasing $\kappa$. Tables of these Gaunt factors are provided.

Paper accepted for publication in Astronomy & Astrophysics. Contains 5 pages, 4 figures, and 9 tables

References in corpus (5)

• Detecting shock waves in cosmological smoothed particle hydrodynamics simulations
• Resolving the electron temperature discrepancies in HII Regions and Planetary Nebulae: kappa-distributed electrons
• Measuring nebular temperatures: the effect of new collision strengths with equilibrium and kappa-distributed electron energies
• Accurate determination of the free-free Gaunt factor; I - non-relativistic Gaunt factors
• Discrepancies between the [OIII] and [SIII] Temperatures in HII Regions

Cited by in corpus (9)

• Tests of Dark MACHOs: Lensing, Accretion, and Glow
• Relativistic electron impact ionization cross sections of carbon ions and application to an optically thin plasma
• Variability of the adiabatic parameter in monoatomic thermal and non-thermal plasmas
• Resonances in nonrelativistic free-free Gaunt factors with screened Coulomb interaction
• X-ray Spectra from Plasmas with High-Energy Electrons: kappa-distributions and e-e Bremsstrahlung
• On collisional free-free photon absorption in warm dense matter
• Non-relativistic free-free emission due to $n-$distribution of electrons - Radiative cooling and thermally averaged and total Gaunt factors
• Plasma Diagnostics From Active Region and Quiet Sun Spectra Observed by Hinode/EIS: Quantifying the Departures from a Maxwellian Distribution
• Electrostatic waves in astrophysical Druyvesteyn plasmas: I. Langmuir waves