| Abstract: Active galactic nuclei (AGN), powered by accretion onto supermassive black holes (SMBHs), profoundly influence the evolution of their host galaxies through feedback. This feedback is a key ingredient in galaxy-formation models, invoked to explain the tight correlations between SMBH mass and host-galaxy properties. Among the various feedback channels, multi-phase outflows—observed in molecular, atomic, and ionised gas—are particularly promising, yet the physical drivers of these outflows and their impact on the interstellar medium (ISM) remain debated. Moreover, while the role of radio jets in shaping the ISM is well established in massive galaxies, their influence in dwarf galaxies is largely unexplored. The recent discovery of AGN in dwarf systems hosting intermediate-mass black holes now challenges traditional models that rely primarily on supernova-driven feedback.
In my thesis, I present a comprehensive, multi-wavelength investigation aimed at addressing three key questions: (a) What triggers outflows in AGN? (b) How does AGN activity regulate star formation in their hosts? (c) Do dwarf galaxies show observable signatures of AGN-driven feedback? To answer these, I assembled and analysed an extensive dataset spanning X-ray (Chandra), UV (AstroSat/UVIT), optical and infrared imaging and IFU spectroscopy (HCT, HST, GEMINI/GMOS(North), SDSS/MaNGA), radio continuum (VLA), and sub-millimetre molecular gas tracers (ALMA).
My results show that (i) ionised outflows are ubiquitous across all AGN classes; (ii) AGN radiation is the dominant driver of these outflows, with radio jets providing an additional boost to the gas kinematics; (iii) AGN activity can enhance, rather than quench, star formation in the nuclear regions; (iv) NGC 4395 exhibits the first clear evidence of jet–ISM interaction on ~10-pc scales in a dwarf galaxy; and (v) both AGN and supernovae jointly shape the feedback cycle in this system. |
