High-energy emission of fast rotating white dwarfs

¹ Korea Astronomy and Space Science Institute, 61-1 Whaam-dong, Yusong-gu, Taejon 305-348, Republic of Korea e-mail: ikhsanov@ast.cam.ac.uk
² Central Astronomical Observatory of the Russian Academy of Sciences, Pulkovo 65/1, 196140 St. Petersburg, Russia
³ Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
⁴ Department of Physics and Astronomy, University of Bonn, Germany

Received: 3 April 2005
Accepted: 29 August 2005

Abstract

The process of energy release in the magnetosphere of a fast rotating, magnetized white dwarf can be explained in terms of the canonical spin-powered pulsar model. Applying this model to the white dwarf companion of the low mass close binary AE Aquarii leads us to the following conclusions. The system acts as an accelerator of charged particles whose energy is limited to  TeV and which are ejected from the magnetosphere of the primary with the rate . Due to the curvature radiation of the accelerated primary electrons the system should appear as a source of soft γ-rays (∼100 keV) with the luminosity <. The TeV emission of the system is dominated by the inverse Compton scattering of optical photons on the ultrarelativistic electrons. The optical photons are mainly contributed by the normal companion and the stream of material flowing through the magnetosphere of the white dwarf. The luminosity of the TeV source depends on the state of the system (flaring/quiet) and is limited to <. These results allow us to understand a lack of success in searching for the high-energy emission of AE Aqr with the Compton Gamma-ray Observatory and the Whipple Observatory.