Thesis - Open Access
Bachelor of Arts
Physics and Astronomy
Galaxy, Metallicity, Spaxel, AGN, Sloan, Digital, Sky, Survey, SDSS, Galactic metallicities, Astronomy, Astrophysics, Border spaxels, Metallicity callibration
In this thesis, I introduce a method to identify and characterize the effects of active galactic nuclei (AGN) on the spectra of nearby star-forming regions. I analyze spatially-resolved areas of galaxies called “spaxels” within Data Release 15 of the Sloan Digital Sky Survey (SDSS) with the goal of locating those which are physically close to AGN. I find those spaxels with calculated metallicities which lie adjacent to AGN-flagged spaxels and characterize their metallicity values relative to the spaxels which are not adjacent to AGN-flagged spaxels, using a total of 11 separate metallicity calibrations. I find that the current methods to mask AGN-influenced regions for large-scale investigation are, in general, robust, as the largest median deviation between metallicities in border spaxels and those in non-border spaxels is 0.0467 dex. The largest mean difference in metallicity between border and non-border spaxels is 0.0522 dex with a standard deviation of 0.0590 dex. However, on a spaxel-by spaxel basis, I find that the differences in metallicity between border spaxels and non-border spaxels can be as large as 0.9350 dex. These results are concerning for spaxel-by-spaxel analysis, and indicate the need for an improved masking process in the future.
Khelil, Aidan, "Characterizing AGN Influence on the Calculated Metallicities of Adjacent Star-Forming Spaxels" (2022). Honors Papers. 856.