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