Anticorrelated lags in a neutron star Z source GX 5-1: AstroSat’s View

We report the cross-correlation function studies of a Neutron star low mass X-ray binary, Z source GX 5-1 using SXT and LAXPC energy bands onboard AstroSat. For first time, we lag between soft (0.8-2.0 keV, SXT) hard (10-20 keV 16-40 LAXPC) in detected lags order few tens to hundreds seconds Horizontal branch. interpreted them as readjustment time scale inner region accretion disc. used various two components three-component spectral models unfold spectra observed changes component fluxes which were exhibiting Branch Oscillation variations. It was that bbody assumed be originating from boundary layer over NS, also found vary along with HBO variation where detected. constrained size Comptonizing 15-55 km assuming due corona. noticed similar after employing other suggest overall corona must explain lags, variation, respective In case study, it noted BL increases top HB upper vertex.