The 1-50 keV spectral and timing analysis of IGR J18027-2016:: an eclipsing, high mass X-ray binary

We report the association of the INTEGRAL source IGR J18027-2016 with the BeppoSAX source SAX J1802.7-2017. IGR J18027- 2016 is seen to be a weak, persistent source by the IBIS/ISGRI instrument on board INTEGRAL with an average source count rate of 0.58 counts s(-1) (similar to 6.4 mCrab) in the 20-40 keV band. Timing analysis performed on the ISGRI data identifies an orbital period of of 4.5696 +/- 0.0009 days and gives an ephemeris of mid-eclipse as, T-mid = 52 931.37 +/- 0.04 MJD. Re-analysis of archival BeppoSAX data has provided a mass function for the donor star, f(m) = 16 +/- 1 M circle dot and a projected semimajor axis of a(x) sin i = 68 +/- 1 lt-s. We conclude that the donor is an OB-supergiant with a mass of 18.8-29.3 M circle dot and a radius of 15.0-23.4 R circle dot. Spectra obtained by XMM-Newton and ISGRI indicate a high hydrogen column density of N-H = 6.8 x 10(22) cm(-2), which suggests intrinsic absorption. The source appears to be a high mass X-ray binary with the neutron star emitting X-rays through wind-fed accretion while in an eclipsing orbit around an OB-supergiant.