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Title: Fermi Bubbles and galactic outflows in circumgalactic medium
Authors: Sarkar, Kartick Chandra
Thesis Advisor: Nath, Biman B.
Subject: Astronomy and Astrophysics
Issue Date: Jul-2017
Publisher: Raman Research Institute, Bangalore
Citation: Ph.D. Thesis, Indian Institute of Science, Bangalore, 2017
Abstract: Galactic outflows play an important role in the formation and evolution of galaxies by regulating the star formation rate (SFR) within them and by throwing out metals into the intergalactic medium (IGM). They are key to understand the relation between the stellar and the dark matter halo mass, mass-metallicity relation of galaxies, intergalactic metal enrichment, formation of high velocity clouds and much more. Galactic outflows have been observed to be present in galaxies at all redshifts either in emission or in absorption of the stellar continuum. Outflows have been also detected in the immediate vicinity of galaxies by probing absorption lines in the spectrum of background Active Galactic Nuclei. In this thesis we explore the interactions between supernovae (SNe) driven outflows and the circumgalactic medium (CGM), an extended hot gas atmosphere believed to be present in the haloes of massive (stellar mass, M? & 1010 M ) galaxies. Given the complexity of geometry and multiphase nature of outflows, we use numerical simulations to study gas interactions. Our results shine light on many interesting aspects of the galactic outflows, such as, i) the effect of the circumgalactic medium on the mass outflow rate and velocity of the outflowing gas on large scales, ii) origin of high velocity cold ( 104 K) gas in outflows iii) origin of X-ray emission in different scenarios. We connect our numerical and analytical work with the X-ray data. We also use our numerical set up to understand the origin and nature of two giant-ray bubbles, called the Fermi Bubbles, at the centre of our Galaxy. We compare our synthetic emission models to the observed -rays, X-rays, radio and UV absorption data and constrain the energetics and age of these bubbles. Below we outline the investigations undertaken in this thesis and point out our main results.
Description: Open Access
Copyright: This thesis is posted here with the permission of the author. Personal use of this material is permitted. Any other use requires prior permission of the author. By choosing to view this document, you agree to all provisions of the copyright laws protecting it.
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