Anisotropic bremsstrahlung emission and the form of regularized electron flux spectra in solar flares

The cross section for bremsstrahlung photon emission in solar flares is, in general, a function of the angle theta between the incoming electron and the outgoing photon directions. Thus the electron spectrum required to produce a given photon spectrum is a function of this angle, which is related to the position of the flare on the solar disk and the direction(s) of the precollision electrons relative to the local solar vertical. We compare mean electron flux spectra for the flare of 2002 August 21 using cross sections for parameterized ranges of the angle theta. Implications for the shape of the mean source electron spectrum and for the injected power in nonthermal electrons are discussed.