  The TeV gamma-ray point source HESSJ1832-093 remains unidentified despite
extensive multi-wavelength studies. The gamma-ray emission could originate in a
very compact pulsar wind nebula or an X-ray binary system composed of the X-ray
source XMMU J183245-0921539 and a companion star (2MASS J18324516-0921545). To
unveil the nature of XMMUJ183245-0921539 and its relation to HESSJ1832-093, we
performed deeper follow-up observations in X-rays with Chandra and Swift to
improve source localisation and to investigate time variability. We observed an
increase of the X-ray flux by a factor ~6 in the Chandra data compared to
previous observations. The source is point-like for Chandra and its updated
position is only 0.3" offset from 2MASS J18324516-0921545, confirming the
association with this infrared source. Subsequent Swift ToO observations
resulted in a lower flux, again compatible with the one previously measured
with XMM-Newton, indicating a variability timescale of the order of two months
or shorter. The now established association of XMMU J183245-0921539 and 2MASS
J18324516-0921545 and the observed variability in X-rays are strong evidence
for binary nature of HESS J1832-093. Further observations to characterise the
optical counterpart as well as to search for orbital periodicity are needed to
confirm this scenario.
