skip to main content

SciTech ConnectSciTech Connect

Title: Theory of gyroresonance and free-free emissions from non-Maxwellian quasi-steady-state electron distributions

Currently there is a concern about the ability of the classical thermal (Maxwellian) distribution to describe quasi-steady-state plasma in the solar atmosphere, including active regions. In particular, other distributions have been proposed to better fit observations, for example, kappa- and n-distributions. If present, these distributions will generate radio emissions with different observable properties compared with the classical gyroresonance (GR) or free-free emission, which implies a way of remotely detecting these non-Maxwellian distributions in the radio observations. Here we present analytically derived GR and free-free emissivities and absorption coefficients for the kappa- and n-distributions, and discuss their properties, which are in fact remarkably different from each other and from the classical Maxwellian plasma. In particular, the radio brightness temperature from a gyrolayer increases with the optical depth τ for kappa-distribution, but decreases with τ for n-distribution. This property has a remarkable consequence allowing a straightforward observational test: the GR radio emission from the non-Maxwellian distributions is supposed to be noticeably polarized even in the optically thick case, where the emission would have strictly zero polarization in the case of Maxwellian plasma. This offers a way of remote probing the plasma distribution in astrophysical sources, including solar active regions as a vividmore » example.« less
Authors:
 [1] ;  [2]
  1. Center For Solar-Terrestrial Research, New Jersey Institute of Technology, Newark, NJ 07102 (United States)
  2. Institute of Solar-Terrestrial Physics, Irkutsk 664033 (Russian Federation)
Publication Date:
OSTI Identifier:
22348128
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 781; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABSORPTION; ASTROPHYSICS; BRIGHTNESS; COMPARATIVE EVALUATIONS; DISTRIBUTION; ELECTRONS; EMISSION; EMISSIVITY; MAGNETIC FIELDS; PLASMA; POLARIZATION; SOLAR ATMOSPHERE; STEADY-STATE CONDITIONS; SUN