Annual Report_Abridged - Second Version - FINAL

21 filaments—the intricate threads that form the universe's vast tapestry. The group has demonstrated that the quantity of highly ionized, low-density, hot gas in the CGM, traced by OVI, is strongly dependent on the mass of low-redshift, star-forming galaxies. For the first time, they conducted robust measurements of the mass of OVI-bearing gas in the CGM of dwarf galaxies. Their findings reveal that in the CGM, the OVI-bearing gas originates from photoionization in dwarf galaxies and from collisional ionization in high-mass galaxies. Moreover, it has been found that the majority of the OVI-bearing gas detected within the virial radius is gravitationally bound to the galaxies, regardless of theirmass. ActiveGalacticNuclei andJets The Universe is filled with billions of galaxies. One in about one thousand galaxies hosts powerful jets that are collimated fountains of plasma shooting out from the centers of these galaxies. Some of these jets are so powerful that they radiate more energy every second than that emitted by the Sun in its entire lifetime of 10 billion years. The research led by Vaidehi Paliya involves studying these jets using the observations from both space- and ground- based telescopes covering the electromagnetic spectrum, i.e., low-frequency radio to gamma rays. Using radio and near-infrared observations, Vaidehi Paliya and his team endeavors to understand the morphology of the jets and their host galaxies and their possible interactions with the surrounding environment. Additionally, the high-energy X-ray and gamma-ray data taken with space observatories such as Chandra X-ray Observatory and Fermi Gamma-ray Space Telescope enables the IUCAA team to explore the radiative mechanisms powering these jets and observational features, e.g., erratic brightness changes noticed from jets on minutes-to-years timescale. Vaidehi Paliya also supplements the observational findings with theoretical modeling to interpret the results. The larger picture addresses some fundamental questions, such as howgalaxies evolve and live their life, interact with their neighbors, and impact their fate. CosmologywithBaryonAcousticOscillation The physics of the early Universe predicts a distinct set of spatial correlations called baryon acoustic oscillations (BAO) that imprint on the large-scale distribution of galaxies in the Universe. The BAO feature shows up as a bump when measuring the pairwise number density of galaxies as a function of pair separation. The length scale at which the BAO feature occurs (typically of order 150 Megaparsec at the present epoch) can act as a standard rod that can be used to constrain cosmological parameters. Measuring the precise value of this scale at different epochs of the Universe is one of the key science drivers of current and upcoming galaxy surveys. Typical analyses in this `BAO cosmology'