College of Science and Mathematics
BA in Physics
We study the emission profiles of 80 active galaxies to find a surrogate for stellar velocity dispersion. We focus on the width of the emission line of once ionized oxygen, [OII], and compare our results to previous work that used [OIII]. In previous research, [OIII] was found to be a good candidate for a surrogate for stellar velocity dispersion, but analysis of the line was complicated by the presence of wings caused by gas infall and outflow in the region. Emission lines with lower ionization levels, like [OII], are known to have less artificial line-broadening from wings. The study of [OIII] used a double Gaussian profile in an attempt to remove the wings. Here we simply fit the [OII] doublet line with two single Gaussian profiles at fixed separation and width. The main benefits of the [OII] line over the [OIII] line are the simpler fitting process, and the fact that [OII] is in a quiet region on the spectra with little interference from other emission lines. We found that the [OII] line still showed wings significant enough to require a fitting of these wings. [OIII] still appears to be the best candidate for a surrogate for stellar velocity dispersion.