L. Zimmermann, V. Grinberg, M. Massi, J. Wilms
The most peculiar radio characteristics of the TeV emitting high-mass X-ray
binary LS I +61{\deg}303 are two periodicities: A large periodic outburst which
exhibits the same period as the orbit (phase \Phi) and a second periodicity of
1667 days (phase \Theta) which modulates the orbital phase and amplitude of the
large outburst. Recent analysis of the radio spectral index present strong
evidence for the presence of the critical transition from optically thick
emission (related to a steady jet) to an optically thin outburst (related to a
transient jet) as in other microquasars. In parallel, a switch from a low/hard
X-ray state to a transitional state (e.g. steep power law state) would be
expected. We show how the critical transition from optically thick emission to
an optically thin outburst is modulated by \Theta. Folding over a too large
\Theta-interval mixes up important information about the outbursts and can
yield a false picture of the emission behaviour of the source along the orbit.
We therefore analyse the implications of this long period for treatment of hard
X-ray/high energy data obtained from LS I +61{\deg}303, e.g. with Fermi-LAT or
INTEGRAL, taking into account this long-term periodicity.
View original:
http://arxiv.org/abs/1111.2692
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