Active galactic nuclei (AGN) are the energetic centers of all massive galaxies that are understood to be the result of mass accretion onto supermassive black holes and the release of gravitational energy. The radio-loud/radio-quiet divide in AGN is one of the enduring open questions in AGN research. It is not completely clear why only a tiny fraction of AGN can launch radio jets that can extend up to intergalactic distances on 100s of kiloparsec scales, while the vast majority of AGN exhibit outflows that are only a few kiloparsecs or less in extent. I will present research carried out by us on addressing these questions through the use of multi-scale radio observations obtained using the Very Large Array (VLA), the Giant Metrewave Radio Telescope (GMRT), and the Very Long Baseline Array (VLBA). I will also describe the results from our polarization-sensitive observations from the VLA and GMRT and what the inferred magnetic field structures reveal about the different AGN classes.
Preeti Kharb obtained her B.Sc. from Miranda House College, Delhi University, in 1994, and her M.Sc. from Delhi University in 1996. She did her pre-Ph.D. from Jawahar Lal University (JNU) in 1997 and obtained her Ph.D. from the Indian Institute of Astrophysics and Bangalore University in 2005. After post-doctoral positions at the Rochester Institute of Technology (RIT) and Purdue University in the USA, she joined the faculty of the Indian Institute of Astrophysics, Bangalore, as a Reader, in 2012. She moved to NCRA in September 2016 and is currently an associate professor there. She works on the phenomenology of Active Galactic Nuclei (AGNs) and is an expert on jet physics in AGNs. This invited seminar is a part of the activities commemorating "75 years of India's Independence: Azadi ka Amrit Mahotsav" at ARIES.