Hello! My name is Ray Garner and I am a postdoc in the Astronomy Group at Texas A&M University in College Station, Texas. I am working with Dr. Rob Kennicutt on the Star formation, Ionized Gas, and Nebular Abundances Legacy Survey (SIGNALS), a survey of HII regions across ~60 galaxies. You can check out the survey paper here.
Before I arrived in College Station, I was a graduate student at Case Western Reserve University in Cleveland, Ohio working with Prof. Chris Mihos on a detailed analysis of the Pinwheel Galaxy (M101) and its small satellite group using the deep, wide-field, narrowband imaging capabilities of the Burrell Schmidt 24/36-inch telescope.
Briefly, my thesis utilizes narrowband images of Hα, Hβ, [OIII]λλ4959,5007, and [OII]λλ3726,3729. These images allowed me to search the entire M101 Group for outlying, intragroup star-forming regions (finding none), measure the oxygen abundance gradient of M101 (suggesting a broken gradient at $R_{25}$), and constrain stellar ages throughout the entire disk (finding a very dynamic spiral pattern). You can read more about that research below, or click here.
Before attending CWRU, I was a student at Furman University in Greenville, South Carolina where I graduated with a B.S. in Physics, Summa Cum Laude. While there, I completed research in general relativity with Dr. Bill Baker (ret.). During the summer of 2017, I attended a Research Experience for Undergraduates (REU) at Indiana University in Bloomington, Indiana. There, I worked on ionized gas kinematics of nearby, low-mass galaxies with the late Dr. Liese van Zee.
PhD in Astronomy, 2023
Case Western Reserve University
BS in Physics, 2018
Furman University
The variations of oxygen abundance and ionization parameter in HII regions are usually thought to be the dominant factors that produced variations seen in observed emission line spectra. However, if and how these two quantities are physically related is hotly debated in the literature. Using emission line data of NGC~628 observed with SITELLE as part of the Star-formation, Ionized Gas, and Nebular Abundances Legacy Survey (SIGNALS), we use a suite of photoionization models to constrain the abundance and ionization parameters for over 1500 HII regions throughout its disk. We measure an anti-correlation between these two properties, consistent with expectations, although with considerable scatter. Secondary trends with dust extinction and star formation rate surface density potentially explain the large scatter observed. We raise concerns throughout regarding various modeling assumptions and their impact on the observed correlations presented in the literature.