939 research outputs found
Evidence for Nonlinear Diffusive Shock Acceleration of Cosmic Rays in the 2006 Outburst of RS Ophiuchi
Spectroscopic observations of the 2006 outburst of RS Oph at both infrared
(IR) and X-ray wavelengths have shown that the blast wave has decelerated at a
higher rate than predicted by the standard test-particle adiabatic shock-wave
model. The observed blast-wave evolution can be explained, however, by the
diffusive shock acceleration of particles at the forward shock and the
subsequent escape of the highest energy ions from the acceleration region.
Nonlinear particle acceleration can also account for the difference of shock
velocities deduced from the IR and X-ray data. We discuss the evolution of the
nova remnant in the light of efficient particle acceleration at the blast wave.Comment: 4 pages, 2 figures. To appear in "RS Ophiuchi (2006) and the
recurrent nova phenomenon", eds. A. Evans, M.F. Bode & T.J. O'Brien, ASP
Conf. Se
Gamma-ray signatures of classical novae
The role of classical novae as potential gamma-ray emitters is reviewed, on
the basis of theoretical models of the gamma-ray emission from different nova
types. The interpretation of the up to now negative results of the gamma-ray
observations of novae, as well as the prospects for detectability with future
instruments (specially onboard INTEGRAL) are also discussed.Comment: 10 pages, 7 figures. Invited talk at the "Gamma 2001" Symposium,
April 4-6, 2001, Baltimore, Maryland. To be published by AI
Prospects for detectability of classical novae with INTEGRAL
Classical novae are potential gamma-ray emitters, both in lines and in a
continuum. Continuum emission (at energies between 20-30 and 511 keV) and line
emission at 511 keV are related to positron annihilation and its Comptonization
in the expanding shell; 18F is the main responsible of positron production. The
lines at 478 and 1275 keV have their origin in the decay of the radioactive
nuclei 7Be and 22Na. Updated models of nova explosions have been adopted for
the computation of the gamma-ray emission. New yields of some radioactive
isotopes directly translate into new detectability distances of classical novae
with INTEGRAL.Comment: Contributed paper at the 4th INTEGRAL Workshop, 4-8 September 2000,
Alicante (Spain). To be published in the ESA-SP series: 4 pages, 4 figure
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