Date of Award
Master of Science (MS)
Physics and Astronomy
Stephen A. Walker
Astronomical spectroscopy, Nebulae, Galaxies
Galaxy clusters and groups are the largest gravitationally bound systems in the universe and have most of their baryonic mass in the form of hot X-ray gas called the intracluster medium (ICM). Many clusters and groups have dense ICM cores with short cooling time (e.g., < 1 Gyr) at the center. The dense ICM can in principle cool to form new stars, accompanied by cold and warm gas cooled from the hot ICM. The warm gas with temperatures of ∼ 10 4 K can be traced by optical emission lines like Hα, [NII] and [SII] in the optical wavelengths. My work has focused on analyzing the imaging and spectral data from optical telescopes to detect the warm gas traced by optical emission lines (particularly Hα and [NII]) at the central giant elliptical galaxies in nearby galaxy groups. I have analyzed the APO-3.5m and SOAR-4.1m data of a large sample (eighty) of giant elliptical galaxies and detected many interesting examples for detailed studies. I summarize my work in this Thesis and focus on optical emission-line nebulae with high equivalent-width. While all the galaxies in the sample host a strong X-ray cool core, only ∼ 15% of them have strong optical emission-line nebulae. My work is an important component of an ongoing multi-wavelength project on these giant elliptical galaxies led by my advisor Dr. Sun. My work has already contributed to one publication with me as a co-author (Liu, Sun et al. 2019)  and three more papers with me as a co-author are in preparation.
Edge, Tim, "Optical emission-line nebulae in giant elliptical galaxies" (2020). Theses. 346.