Thomas Nelson, Davide Donato, Koji Mukai, Jeno Sokoloski, Laura Chomiuk
Classical nova events in symbiotic stars, although rare, offer a unique
opportunity to probe the interaction between ejecta and a dense environment in
stellar explosions. In this work, we use X-ray data obtained with Swift and
Suzaku during the recent classical nova outburst in V407 Cyg to explore such an
interaction. We find evidence of both equilibrium and non-equilibrium
ionization plasmas at the time of peak X-ray brightness, indicating a strong
asymmetry in the density of the emitting region. Comparing a simple model to
the data, we find that the X-ray evolution is broadly consistent with nova
ejecta driving a forward shock into the dense wind of the Mira companion. We
detect a highly absorbed soft X-ray component in the spectrum during the first
50 days of the outburst that is consistent with supersoft emission from the
nuclear burning white dwarf. The high temperature and short turn off time of
this emission component, in addition to the observed breaks in the optical and
UV lightcurves, indicate that the white dwarf in the binary is extremely
massive. Finally, we explore the connections between the X-ray and GeV
gamma-ray evolution, and propose that the gamma ray turn-off is due to the
stalling of the forward shock as the ejecta reach the red giant surface.
View original:
http://arxiv.org/abs/1201.5643
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