Resolving the Truth: The role of local environment in star formation and low-level nuclear activity in nearby galaxies
Abstract
Nuclear activity and star formation exhibit different properties with observed spatial scale. To fully understand them, we must consider the local environment's impact on measured global properties. My dissertation focuses on the spatially resolved excitation mechanisms that power observed emission, and the dust that obscures it. Low ionization nuclear emission regions (LINERs) are a common occurrence in nearby galaxies, and are often explained by low-level nuclear activity. But this energy source is not sufficient to power the observed emission lines that define LINERs on 100 pc scales. Using HST/STIS, we resolved the nuclear regions of three nearby LINERs on scales of ~9 pc to track the dominant power source with distance from the nucleus. The resulting physical model involved photoionization from the central engine within the central 20 pc, and shock excitation at larger distances. We conclude that integrated LINER-like emission can be explained by a combination of AGN photoionization and shocks on different spatial scales. Star formation is the most prevalent energy source across all galaxies, making its advancement and cessation in galaxies vital for galaxy evolution. However, our current understanding of star formation is highly dependent on dust attenuation, which itself depends on the spatial scales and properties on which it is observed. We studied the attenuation law of kpc-size star forming regions in ~30 nearby galaxies using Swift NUV photometry and SDSS-IV/MaNGA optical IFU spectroscopy. We compared the resulting attenuation relation with that of the parent galaxy, connecting the local properties to the integrated galaxy light. Through spatially resolved studies of the processes that create and obscure observable emission, my dissertation work provides context for the physical processes that dictate the integrated properties in star forming galaxies and LINERs, and of their place in galaxy evolution.
- Publication:
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American Astronomical Society Meeting Abstracts #233
- Pub Date:
- January 2019
- Bibcode:
- 2019AAS...23341202M