Save Big on Coursera Plus. 7,000+ courses at $160 off. Limited Time Only! Grab it Explore the fascinating world of emission line regions in active galaxies through this comprehensive lecture by Dr. Swayamtrupta Panda from Laboratório Nacional de Astrofísica, Brazil. Delve into the historical significance of studying these regions, from confirming the extragalactic origin of Active Galactic Nuclei (AGNs) to their current use as "standardizable" cosmological candles. Discover recent advancements in AGN variability studies in preparation for the Large Synoptic Survey Telescope (LSST) and learn about the AGN Polish Consortium's contributions. Examine the progress in using quasars for cosmology, focusing on the broad-line region size-luminosity relation and its implications. Gain insights into how theoretical developments and improved telescope capabilities have enhanced our understanding of these cosmic systems, with particular emphasis on the James Webb Space Telescope (JWST) and the upcoming Vera C. Rubin Observatory's LSST.