About Me

I am a fourth year graduate student in Astronomy at the University of Arizona and a National Science Foundation Graduate Research Fellow working with Professor Dan Marrone. Prior to my time in Arizona, I completed my Undergraduate degree in astronomy and physics at the University of Michigan.

I study galaxy evolution, focusing primarily on the cold, dense gas that is required to form new stars. My work involves using both observational and theoretical tools to understand the evolution of this gas across the history of the universe, from only a few hundred million years after the big bang up to the present day.

I am also involved in a number of programs aimed at making education and academia more accessbile and diverse. Most recently, I have been a coordinator of the Mentorship and Education for SCIence in Tucson (MESCIT) program.

In my free time I like to bake and cook. Since the beginning of the COVID-19 pandemic I have set out to recreate taco recipes from some of my favorite restaurants in Tucson.

Research

The History of Star Forming Gas

My primary research interest is understanding the processes that form and shape galaxies. Cold gas in the form of molecular Hydrogen is thought to be the precursor to the birth of new stars. Tracing the properties of this gas will help us to better understand how stars formed in galaxies throughout the history of the universe, and may provide the key to understanding why stars today form at only 10% of the rate that they did when the universe was younger.

Study of molecular gas in the early universe requires extremely sensitive millimeter and sub-millimeter wavelength observations with telescopes such as the Atacama Large Millimiter/submillimeter Array (ALMA). Because of the long observation times required to do this type of research, studies to date have focused on extremely small regions of the sky. This may result in sampling biases and uncertainties that hinder our understanding. My most recent work uses cosmological simulations to understand the extent of these biases and develop tools to account for them.

In addition to observing molecular gas in the past, we also need to understand its behavior in the present. Many properties of molecular gas, such as the relationships between different spectral lines that are used to trace its abudnance, are poorly understood even in nearby galaxies. To this end, I am conducting a survey of multiple molecular gas spectral lines in nearby galaxies to understand how their luminosities correlate with one another and various other galaxy properties.

Related Publications
" Biases and Cosmic Variance in Molecular Gas Abundance Measurements at High Redshift", R. P. Keenan, D. P. Marrone, & G. K. Keating 2020, The Astrophysical Journal, in press

Intensity Mapping

Intensity mapping is a novel tool for studying gas in the distant universe. The traditional approach to studying distant galaxies has been to select a small number of objects to observe in great detail; this provides a wealth of information about individual galaxies, but may miss important statistical trends. Intensity mapping allows us to study large samples of galaxies, many too faint to be detected in the traditional approach, by combining their light statistically. This tool will provide complimenatry information to the detailed traditonal studies by surveying galaxies over enormous volumes of space.

I am a collaborator on the Millimeter Intensity Mapping Experiment (mmIME; P.I. Karto Keating), which has recently presented a detection of the Carbon Monoxide shot power spectrum using ALMA. I am also involved in a number of projects to create state of the art instruments for intensity mapping studies. These include the Tomographic Ionized-carbon Mapping Experiment (TIME), a multi-pixel submillimeter spectrometer being installed at the Arizona Radio Observatory, and the Terahertz Intensity Mapper (TIM) a ballon-borne telescope currently under construction.

Related Publications
" An Intensity Mapping Detection of Aggregate CO Line Emission at 3 mm", G. K. Keating, D. P. Marrone, G. C. Bower, & R. P. Keenan 2020, The Astrophysical Journal, in press

Star Formation in the First Galaxies

Haro 11 [OIII]/[OII] Fraction

As an undergraduate I worked with Professor Sally Oey to study nearby dwarf galaxies believed to be analogs to some of the first star forming galaxies that ionized the early universe. I helped develop a tool to identify signatures of powerful bursts of star formation that pour intense Lyman continuum light into the intergalactic medium. I then applied this tool to pinpoint the source of Lyman continuum emission in Haro 11. Our results have since been verified by other groups using much more extensive, but time consuming, methods.

Related Publications
" Haro 11: Where is the Lyman Continuum Source?", R. P. Keenan, M. S. Oey, A. E. Jaskot, & B. L. James 2017, The Astrophysical Journal, 848, 12
" Mapping Lyman Continuum Escape in Tololo 1247-232", G. Micheva, M. S. Oey, R. P. Keenan, A. E. Jaskot, & B. L. James 2018, The Astrophysical Journal, 867, 1

Outreach

I am involved in a number of programs that seek to make higher education more accessible to groups that have historically been underrepresented in academia in general and science in particular. Since 2018 I have been a coordinator for Mentorship and Education for SCIence in Tucson (MESCIT), a program that provides math tutoring for high school students from Tucson's Native American and refugee communities. My primary role is to connect tutors, students, the school and funders while making sure the tutoring runs smoothly. I also collect data about how well our program is working and produce reports and recommendations for improvements.

Logo design: Nazanin Shivaei