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High-energy emission of fast rotating white dwarfs
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. First, the
system acts as an accelerator of charged particles whose energy is limited to
E_p < 3 TeV and which are ejected from the magnetosphere of the primary with
the rate L_kin < 10^{32} erg/s. Due to the curvature radiation of the
accelerated primary electrons the system should appear as a source of soft
gamma-rays (~ 100 keV) with the luminosity < 3x10^{27} erg/s. 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 < 5x10^{29} erg/s.
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.Comment: 8 pages, accepted for publication in A&
TeV Cherenkov Events as Bose-Einstein Gamma Condensations
The recent detection of gamma radiation from Mkn 501 at energies as high as
25 TeV suggests stringent upper bounds on the diffuse, far infrared,
extragalactic radiation density. The production of electron-positron pairs
through photon-photon collisions would prevent gamma photons of substantially
higher energies from reaching us across distances of order 100 Mpc. However,
coherently arriving TeV or sub-TeV gammas - Bose-Einstein condensations of
photons at these energies - could mimic the Cherenkov shower signatures of
extremely energetic gammas. To better understand such events, we describe their
observational traits and discuss how they might be generated.Comment: 12 pages, 2 figures, accepted for publication in Ap.J.(Lett.
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