Searching for the Next Generation of OH Megamasers

OH Megamasers (OHMs) are rare, astrophysical masers produced by major galaxy mergers. The OHM spectral lines can "spoof" similar signals as the 21cm neutral Hydrogen (HI) line from spiral galaxies at different redshifts. While this hasn't yet significantly impacted past HI surveys, current and future surveys on the Square Kilometere Array (SKA) and its precursors will be reaching groundbreaking redshifts and depths - unknowingly detecting science-rich, never-before-seen OHMs. To reduce this "contamination" and utilize OHMs to their fullest potential, a method for sorting OH from HI sources without optical spectroscopic redshifts is absolutely paramount.

I have created for a proxy to sort these two populations from each other using near- to mid-IR photometry and a k-Nearest Neighbors algorithm. This method utilizes the vast amount of IR photometry available from missions like WISE and Spitzer's IRAC to measure small differences in star formation that is observed between HI sources and OH megamaser hosts. This can accurately identify OH megamasers over 99% of the time. Read the paper here.

This work is done in support of the several current and upcoming HI surveys on Square Kilometre Array (SKA) precusors. This includes Apertif, an HI survey on the Westerbork Synthesis Radio Telescope, where our algorithm correctly identified an early OH megamaser detection (Hess, Roberts, et al. 2021). Looking at the Distant Universe with the MeerKat Array (LADUMA) is another SKA precursor that is utilizing this algorithm and has already discovered the highest redshift OH megamaser to date (Glowacki et al. 2022).

Discovery of the highest redshift OH megamaser

Looking at the Distant Universe with the MeerKat Array (LADUMA) recently discovered the most distant OH megamaser after just one night of observing on the MeerKAT Arary. This discovery is just a first glimpse at the future of OHM detections. My advisor, Jeremy Darling, and I recently were able to chat with Dan Strain about this exciting discovery.

Past Work

In Search of Inflation

Polarbear is a ground-based experiment searching for a small signal of polarization in the Cosmic Microwave Background (CMB) that would be the smoking gun for inflation. For Polarbear, I tested, characterized, and designed detectors that are deployed to the telescope to measure these small signals. (AAS 232 Poster)

Solar Image Processing

Understanding the Earth’s climate requires understanding the Sun. The Precision Solar Photometric Telescope (PSPT) located at the Mauna Loa Solar Observatory acquires images of the Sun to monitor the evolution of the solar surface. I processed raw images coming from the telescope to remove false features and artifacts and prepare them as a scientific package. (AGU 2015 Poster)

Undergraduate Work

As an undergraduate, I studied laser assisted electron scattering. Further, I worked in the machine shop on campus building pieces and machinery, including a milling machine and CNC. I also taught students how to use the equipment.

Education & Outreach

Since the beginning of 2022, I began working at the Lookout Mountain Youth Center in Golden, CO to help students successfully obtain their GEDs on graduation by teaching math and science classes and offering individual tutoring as needed. Since this program is the first of its type, we are working to get more graduate students from CU established at the center in order to continue to help students succeed when they graduate.

Image from APS Hack Day 2019

As the field of astronomy moves towards bigger and bigger data, the amount of data science expertise needed to be a successful scientist will also grow. In order to facilitate this in APS, in fall 2019, I received departmental funding and support to hold the first APS Hack Day in which I brought in speakers with a range of expertise to present about a certain topic in data science. This event was attended by >40 people including graduate students, undergraduate students, post-docs, and faculty.

More information about the APS Hack Day, including resources from the event, can be found here.

Image from Boulder Junior Astronauts

In 2019, I designed and taught an after-school enrichment program for 4th and 5th graders in the Boulder Valley School District called Boulder Junior Astronauts. Each week, we would "visit" a new planet and perform hands on experiments to learn something new about each of the planets in our Solar System.

After I refined the curriculum, I trained other graduate students at CU Boulder across a range of departments who now teach the program at elementary schools across Boulder.


Making astronomy a more diverse and inclusive field is a goal that I share with many others. Fron 2016-2021, I ran a group called Promoting an Inclusive Community in Astronomy (PICA) where we discuss these exact goals with regular meetings. Though we are largely a discussion group, we take action when needed. For example, we had an open conversation with campus advocates and lawyers about how the end of DACA (Deferred Action for Childhood Arrivals) will affect astronomy and how we can protect and support students or staff with DACA. We also strongly advocated for abolishing the Physics GRE requirement in the department due to the known biased nature of the exam and were able to change to optional for future applicants.

In AAS, I am a member of the Working Group on Accessibility and Disability (WGAD) and the WGAD representative on the Site Visit Oversight Committee.

I have also served on many committees within the Astrophysical and Planetary Sciences department (APS) at University of Colorado Boulder that aim to make our department a better place. This includes:

  • Concerns Committee - a committee that is dedicated to solving internal issues in the department
  • Exams Committee - a committee of students and faculty that make sure our comprehensive exams are fair
  • Faculty Search Committee - a committee in charge of hiring a time-domain astronomy faculty member
  • Admissions Set-Up Committee - a committee that was assembled in order to create a fair and inclusive admissions process for prospective CU Boulder APS graduate students
  • Admissions Committee - a committee in charge of reading and evaluating >300 applicants to CU Boulder APS Graduate Program
  • Faculty Committee - a committee of two students that represent the graduate students at faculty meetings and report back to the graduate students what the faculty discussed in each meeting

About Me

My name is Hayley Roberts (she/her/hers) and I am interested in all things OH megamasers, galaxy evolution, and HI surveys.

I am currently a PhD candidate in the Astrophysical and Planetary Sciences Department at the University of Colorado - Boulder and will be graduating in the Spring of 2023. Before graduate school, I received my B.S. in Physics from Illinois Wesleyan University.

I am passionate about space but also inclusivity and diversity in the field. Outside of research and outreach, I enjoy learning about data science and visualization.

You can contact me at Hayley.Roberts(at)

Hayley Roberts