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Title: Gamma-ray light curves and spectra of classical novae
ABSTRACT The nucleosynthesis in classical novae, in particular that of radioactive isotopes, is directly measurable by its γ-ray signature. Despite decades of observations, MeV γ-rays from novae have never been detected – neither individually at the time of the explosion, nor as a result of radioactive decay, nor the diffuse Galactic emission from the nova population. Thanks to recent developments in modelling of instrumental background for MeV telescopes such as INTEGRAL/SPI and Fermi/GBM, the prospects to finally detect these elusive transients are greatly enhanced. This demands for updated and refined models of γ-ray spectra and light curves of classical novae. In this work, we develop numerical models of nova explosions using sub- and near-Chandrasekhar CO white dwarfs as the progenitor. We study the parameter dependence of the explosions, their thermodynamics and energetics, as well as their chemical abundance patterns. We use a Monte Carlo radiative transfer code to compute γ-ray light curves and spectra, with a focus on the early time evolution. We compare our results to previous studies and find that the expected 511-keV-line flash at the time of the explosion is heavily suppressed, showing a maximum flux of only $$10^{-9}\, \mathrm{ph\, cm^{-2}\, s^{-1}}$$ and thus making it at least one million times fainter than estimated before. This finding would render it impossible for current MeV instruments to detect novae within the first day after the outburst. Nevertheless, our time-resolved spectra can be used for retrospective analyses of archival data, thereby improving the sensitivity of the instruments.  more » « less
Award ID(s):
2011759
PAR ID:
10437815
Author(s) / Creator(s):
;
Date Published:
Journal Name:
Monthly Notices of the Royal Astronomical Society
Volume:
516
Issue:
1
ISSN:
0035-8711
Page Range / eLocation ID:
1008 to 1021
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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