MR. SIBASISH LAHA

Warm absorption in the soft X-ray spectra has been detected among 50% of the Seyfert 1 galaxies in nearby universe. We make a detailed study of warm absorber properties using a sample of Seyfert 1 galaxies having a range of blackhole masses and redshifts. We use the medium resolution (EPIC-pn) as well as high resolution (RGS) data of the XMM-Newton satellite to determine the 0.3-10 keV continuum properties as well as the warm absorber parameters (when present) for the sources. These warm absorber features are mainly detected in the energy range 0.3-2 keV. This is also the region where most Seyfert 1 galaxies show a presence of an excess over 2-10 keV powerlaw spectra, called the "soft-excess". And since the warm absorber parameters are dependent on how we model the continuum it becomes imperative for us to study the soft excess as well. We have studied two bright sources ESO198-G24 and Eso511-G030 for the origin of the soft-excess. We have carried out a study on the relation of how the soft-excess modeling modifies the warm absorption parameters using a well known source IRAS13349+2438. We have also made a detailed study of the variability of warm absorption in a source MRK 1040.