| Abstract : | In the innermost regions of Active Galactic Nuclei (AGN), the matter is understood to be flowing onto the Supermassive black hole (SMBH), which forms an accretion disk. This disk is responsible for the optical/UV continuum emission observed in the spectra of AGN. Reverberation Mapping of the accretion disk using multiple bands can yield the structure of the disk. The simple lamppost model implies a disk that irradiates in the X-ray wavelengths, and the photons are reprocessed in the form of UV and optical wavelength emissions. As the emission is expected to be of the black body type peaking at different wavelengths, depending on the temperature of the disk, continuous, simultaneous monitoring in multiple wavelengths ranges to cover hotter inner regions and cooler outer regions are expected to yield the structure and temperature profile of the accretion disk itself. Using the 3 optical band light curves from the ZTF survey, we have measured the accretion sizes for 19 AGN with SMBH masses obtained through previous reverberation mapping campaigns. We found that the disk sizes are on average 3.8 times larger than the expectations of the SS disk for most sources, which agrees with the recently obtained results. Further, the disk sizes obtained are weakly correlated with the SMBH mass and the AGN luminosity. To understand the accretion disk further using multi-band observations, and test various accretion disk models we are monitoring a sample of bright but intrinsically low luminosity AGN using a combination of telescopes. For 5 AGN in our sample, the observations are completed. We will present the new results obtained from these observations, and discuss the possibility of other models for the AGN accretion disks in order to resolve the size discrepancy. |
