IGR J16195-4945 is a hard X-ray source discovered by INTEGRAL during the Core
Program observations performed in 2003. We analyzed the X-ray emission of this
source exploiting the Swift-BAT survey data from December 2004 to March 2015,
and all the available Swift-XRT pointed observations. The source is detected at
a high significance level in the 123-month BAT survey data, with an average
15-150 keV flux of the source of ~1.6 mCrab. The timing analysis on the BAT
data reveals with a significance higher than 6 standard deviations the presence
of a modulated signal with a period of 3.945 d, that we interpret as the
orbital period of the binary system. The folded light curve shows a flat
profile with a narrow full eclipse lasting ~3.5% of the orbital period. We
requested phase-constrained XRT observations to obtain a more detailed
characterization of the eclipse in the soft X-ray range. Adopting resonable
guess values for the mass and radius of the companion star, we derive a
semi-major orbital axis of ~31 R_sun, equivalent to ~1.8 times the radius of
the companion star. From these estimates and from the duration of the eclipse
we derive an orbital inclination between 55 and 60 degrees. The broad band
time-averaged XRT+BAT spectrum is well modeled with a strongly absorbed flat
power law, with absorbing column N_H=7x 10^22 cm^(-2) and photon index
Gamma=0.5, modified by a high energy exponential cutoff at E_cut=14 keV.Comment: 5 pages, 5 figures, 2 tables. Published on MNRA
