MR. MAINPAL

Active galactic nuclei (AGNs) such as quasars and Seyfert 1 are the most luminous, long-lived and quasi-isotropic sources in the Universe. These sources exhibit complex broadband spectra and complicated timing behavior. The X-ray to UV/Optical emission regime of a Seyfert I is dominated with soft X-ray excess (~0.1-2 keV), powerlaw emission (~2-10 keV) and big blue bump (UV/Optical band). The variability associated with UV/Optical emission is less well understood to date. However, this can be related to the changes caused by various physical process such as either Comptonization in the different regions of the disc or X-ray heating in the disc or accretion flow in the disc or extinction/absorption in the line of sight. We address this issue based on timing and broadband spectral studies of Seyfert I galaxies 1H~0419-577 and Fairall 9. We find that the UV/Optical emission is sometimes affected by various emission components from coronal X-rays and broad line region, and sometimes clear detection of a dominating mechanism such as X-ray reprocessing.