X-ray Emission From Planets Venus and Mars: Theoretical Model and Numerical Simulations

Recently X-ray emission from non-magnetic planets Venus and Mars have been discovered by Chandra X-ray telescopes [1,2]. Analysis of observational data shows that either charge exchange model or fluorescent scattering of solar x-rays cannot explain the whole set of observational data. The premise of this paper is that x-ray emission of both planets is a combination of line k-shell radiation and Bremmstrahlung produced by energetic electrons interacting with planetary atmospheres. Due to the absence of their planetary magnetospheres, planetary bow shocks are located quite close to the ionospheres and on both planets their ionospheres are directly exposed to the shocked solar wind flow. In situ observations revealed the existence at the ionospheric boundaries of strongly turbulent layer -- the so-called plasma mantle. Previous hybrid simulations (kinetic ions and hydro dynamical electrons) have shown that mantle turbulence is produced by interaction of counterstreaming ion populations of the solar wind and planetary ionospheres. Recently developed particle in cell (fully kinetic) code demonstrated that mantle turbulence is responsible for electron acceleration in an agreement with in-situ observations that revealed the presence in mantle electrons with energies up to several hundred eV.[3] In the present paper we incorporated energetic electron distribution obtained by numerical simulations into ADAS code [4] and compared results with observations.

1. K. Dennerl et.al. A&A 286, 319 (2002). 2. K. Dennerl, A&A 394, 1119-1128 (2002). 3. K. Szego et.al. J6R 112, 2175 (1997) 4. http: adas.phystretch ac.uk