Unveiling gravitationally lensed, high-redshift dusty star forming galaxies with JWST
Phadke, Kedar A.
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https://hdl.handle.net/2142/125659
Description
Title
Unveiling gravitationally lensed, high-redshift dusty star forming galaxies with JWST
Author(s)
Phadke, Kedar A.
Issue Date
2024-05-14
Director of Research (if dissertation) or Advisor (if thesis)
Vieira, Joaquin D
Doctoral Committee Chair(s)
Vieira, Joaquin D
Committee Member(s)
Menanteau, Felipe
Ricker, Paul
Wong, Tony
Department of Study
Astronomy
Discipline
Astronomy
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Dusty Star Forming Galaxies
Jwst
High-redshift Galaxies
Language
eng
Abstract
Dust is an important ingredient in galaxy evolution. Dusty star-forming galaxies (DSFGs) have been shown to contribute significantly to the cosmic star formation history. However, their stellar content especially at high redshift has been difficult to observe before the James Webb Space Telescope (JWST) due to the high dust obscuration. Along with most of the sub-fields of astronomy, our understanding of DSFGs is already beginning to change with just two years of JWST’s science data collection. The work presented in this thesis does not even scratch the surface of the capacity JWST has in placing DSFGs in the context of other galaxies. I begin with introducing the parent sample of DSFGs discovered with the South Pole Telescope Sunyaev-Zel’dovich (SPT-SZ) survey. The sample of 81 galaxies was selected on their mm-wavelength emission in cosmic microwave background (CMB) maps and followed up extensively using telescopes like Atacama Pathfinder EXperiment (APEX), Atacama Large Millimeter Array (ALMA), and Australia Telescope Compact Array (ATCA) as well as optical/near-IR telescopes like Hubble Space Telescope (HST), Spitzer, Gemini, and Very Large Telescope (VLT) to reveal their high-redshift and strongly lensed nature. The optical and near-IR imaging is mainly dominated by the foreground lens whereas high resolution sub-millimeter imaging shows galaxy-scale lensed arcs for 90% of the sources. The other 10% are either confirmed protoclusters or candidates. These sources are all luminous infrared galaxies (LIRGs)/ hyper-luminous infrared galaxies (HyLIRGs) in the redshift range of 1.8 to 6.9. I present pre-JWST constraints on active galactic nuclei (AGN) fraction among the full SPT sub-millimeter galaxy (SPT-SMG) sample along with a handful of stellar mass constraints that were possible. Using upper limits from the Wide-field Infrared Survey Explorer (WISE) band 4, I found that the IR luminosity for SPT-SMGs is not dominated by an obscured AGN. The rest of my thesis focuses on my contributions to the JWST -TEMPLATES early release science (ERS) program which includes two sources from the SPT-SMG sample. I describe various data reduction steps for improving the JWST pipeline derived products, specifically for the Mid-Infrared Instrument (MIRI) imaging and medium-resolution spectrometer (MRS) intergral field unit (IFU) data. Methods for reducing the effect of readout noise have been implemented for TEMPLATES-ERS data products and the corresponding cookbooks have been released to the community. Multiple algorithms to remove cosmic ray showers from MIRI MRS data were tested and a cookbook to improve MRS data has also been released. The two SPT-SMGs observed with JWST are found to be close to the main sequence of galaxies. I then present a spatially resolved study of one source: SPT0418-47. Based on Hα and Paα observations, nebular reddening is estimated for the source on scales of around 300 pc. I have compared the attenuation-corrected resolved star-formation rate diagnostics with Paα and IR luminosity for the source. These diagnostics would not have been possible before JWST in a high-redshift DSFG. These observations and this work lays the foundation for similar studies in other sources from the SPT-SMG sample and beyond.
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