Abstract: | Recent observations of GeV/TeV photon emission from several X-ray binaries
have sparked a renewed interest in these objects as galactic particle
accelerators. In spite of the available multi-wavelength data, their
acceleration mechanisms are not determined, and the nature of the accelerated
particles (hadrons or leptons) is unknown. While much evidence favors leptonic
emission, it is very likely that a hadronic component is also accelerated in
the jets of these binary systems. The observation of neutrino emission would be
clear evidence for the presence of a hadronic component in the outflow of these
sources. In this paper we look for periodic neutrino emission from binary
systems. Such modulation, observed in the photon flux, would be caused by the
geometry of these systems. The results of two searches are presented that
differ in the treatment of the spectral shape and phase of the emission. The
’generic’ search allows parameters to vary freely and best fit values, in a
’model-dependent’ search, predictions are used to constrain these parameters.
We use the IceCube data taken from May 31, 2007 to April 5, 2008 with its
22-string configuration, and from April 5, 2008 and May 20, 2009 with its
40-string configuration. For the generic search and the 40 string sample, we
find that the most significant source in the catalog of 7 binary stars is
Cygnus X-3 with a 1.8% probability after trials (2.1 {sigma} one-sided) of
being produced by statistical fluctuations of the background. The
model-dependent method tested a range of system geometries - the inclination
and the massive star’s disk size - for LS I +61 303, no significant excess was
found. |