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A Near-Infrared Look at Bulgeless and Dwarf Galaxies: An Investigation of Obscured AGN and Their Outflows

  • Author(s): Bohn, Thomas
  • Advisor(s): Canalizo, Gabriela
  • et al.
Creative Commons 'BY' version 4.0 license
Abstract

It is now widely accepted that supermassive black holes (SMBHs) lie at the center of most massive galaxies. While SMBHs in these hosts have been well documented and studied, those in lower mass hosts, such as dwarf and spiral galaxies without a central bulge component (i.e. bulgeless galaxies), have remained quite elusive and insufficiently studied. Identifying and examining exactly how active galactic nuclei (AGN) co-evolve and influence bulgeless and dwarf host galaxies is the foundation of my dissertation research. These galaxies can be used as local analogs of the infant Universe (gas rich, low metallicity, rapidly growing) and their BH number density and occupation fraction can provide important constraints on the BH seed population. However, these AGN are difficult to study since they are energetically weak or heavily obscured. The IR provides a unique and compelling avenue to study these AGN since it is not as severely affected by dust obscuration as optical observations. As such, my research utilizes IR selection techniques and observations to identify a new population of obscured AGN that have been overlooked by large optical surveys. Much of my work has focused on coronal lines (CLs), outflows, and analyzing the impacts of AGN on their hosts. In my publications, we confirm AGN activity in a sample of dwarf and bulgeless galaxies through the presence of CL and hidden broad-line emission. In many of these, we find fast, kpc outflows that are likely driven by the AGN. We also find that the outflowing gas have sufficient escape velocities to allow the gas to enrich the circumgalactic medium. As a result, these outflows have the potential to suppress star formation and could play a key role in dwarf and bulgeless galaxy evolution. Additionally, these observations can help deliver key constraints to improve the theoretical feedback models of dwarf and bulgeless galaxies.

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