Abstract Details

Name: Sriram Sankar
Affiliation: South African Astronomical Observatory, Cape Town, 7925
Conference ID: ASI2021_132
Title : Probing the Circumgalactic Medium using absorption line spectroscopy of background quasars.
Authors and Co-Authors : Anand Narayanan (IIST) Jane Charlton (PSU) Bart Wakker, Blair Savage (University of Wisconsin) Vikram Khaire (IIST) Jayadev Pradeep (ISRO)
Abstract Type :
Abstract Category : Extragalactic Astronomy
Abstract : Absorption line spectroscopy is a powerful tool for observations of gas in a wide spectrum of environments, from the dense interstellar regions in star-forming galaxies to the diffuse filamentary structures that define the cosmic web. The Circumgalactic Medium (CGM) is a multiphase, metal-enriched, dynamically complex, massive baryon reservoir that resides in the extended dark matter halo of galaxies. The CGM and the host galaxy share a symbiotic relationship where the CGM regulates star formation and the galaxy feedbacks enrich the CGM. Statistical sampling, high resolution simulations, and multi-wavelength observations are employed to study the complex density profile, phase structure, and kinematics of the CGM wherein lies the clues to various open quandaries in galaxy evolution. By analysing the spectral imprints created by different ions residing in the foreground CGM of galaxies on the spectra of targeted background QSOs, we can study the transverse physical and chemical properties of the CGM. The picture of the CGM emerging through several absorption line studies and hydrodynamic simulations is that of a multiphase medium that is composed of Hydrogen and Metals at various ionizations tracing gas in different temperature and density regimes. With the metals, especially the lower ionizations arising from patches in pc to even a few kpc confined in a diffuse hot corona. I will present work reported in Sankar et al. 2020 where we utilize a series of diagnostic ions spanning a wide range of ionization energies and component by component modelling to extract information on the small-scale metallicity-density-temperature structure of the CGM. I will also present results from Pradeep et al. 2020 where we have used the absorption line technique to study analoges of Milky Way HVCs in an extragalactic context. Our findings are consistent with a patchy metal distribution in the overall CGM environment.