image: Kevin Bandura, an engineer in the West Virginia University Benjamin M. Statler College of Engineering and Mineral Resources, designs radio telescope technology to help astronomers understand the expansion of the universe by measuring dark energy.
Credit: WVU Photo/Brian Persinger
Scientists know dark energy makes up about 70% of the universe and is responsible for the universe’s accelerating expansion. Beyond that, little about it is certain, so WVU engineer Kevin Bandura is enhancing the calibration of radio telescopes that can tell astronomers about dark energy by measuring the “neutral hydrogen” in the universe, a simple form of hydrogen with no net electric charge.
An expert on the design of radio astronomy instruments, Bandura is an associate professor in the Lane Department of Computer Science and Electrical Engineering at the WVU Benjamin M. Statler College of Engineering and Mineral Resources and a member of the Center for Gravitational Waves and Cosmology in the Department of Physics and Astronomy at the WVU Eberly College of Arts and Sciences.
His research focuses on the Canadian Hydrogen Intensity Mapping Experiment, a custom-built radio telescope known as “ CHIME,” and on the Canadian Hydrogen Observatory and Radio-transient Detector, a radio telescope currently under construction that’s known as “CHORD.”
“We’re developing a new technique to measure the telescopes’ response to the sky and reduce the uncertainties, so we can better measure dark energy,” Bandura said. “We're also trying to get better data from the telescope, and to reanalyze the data we have to try to get a dark energy measurement for the first time.”
He uses advanced signal processing and detector technology to improve the ability of radio telescopes to detect a radio wave produced by neutral hydrogen atoms, called the “21-centimeter signal.”
The information radio telescopes detect about the 21-centimeter signal allows astronomers to understand the patterns and formations of large-scale structures in the universe, such as long threads or dense clusters of galaxies, or voids with no galaxies at all. Together, those enormous structures form a cosmic spiderweb across the universe. Neutral hydrogen collects like dewdrops along its strands, and when astronomers measure the distribution of neutral hydrogen throughout the universe over eons, they see the changing shape of that web and collect evidence about how dark energy is driving the expansion of the universe.
By reducing foreground contamination from nearby sources of radio waves like the Milky Way, Bandura said his team can help CHIME and other radio telescopes detect large-scale structures within the cosmic web using the 21-centimeter signal alone.
To do that, Bandura will deploy a chip he developed on radio telescopes and drones, producing a signal-to-noise ratio strong enough to enable the precise calibration astronomers need to detect and analyze radio waves emitted by neutral hydrogen.
Previously, working with researchers from Yale University and Canadian astronomers, Bandura developed a radio calibrator source using a new, fast chip that can be flown on a drone with a signal-to-noise ratio good enough for precise calibration. He’ll now update this radio calibrator source for wider bandwidth and improved stability, “developing the ability to use multiple of these sources simultaneously and put them on drones to calibrate new telescope arrays,” he said.
His team will also create tools for studying 21-centimeter signals, including more accurate models of how radio telescopes receive signals, improved signal-processing techniques for removing noise from the signal and robust new methods for filtering noise.
The goal, Bandura said, is for CHIME to independently detect patterns in the large-scale structure of the universe, including ‘baryon acoustic oscillation signals,’ which illuminate the pattern of empty spaces between galaxies and hold clues to the secrets of dark energy.
Undergraduate students involved in the research will lead the development of a radio receiver outreach lab that includes an instrument similar to the receivers used at CHIME and CHORD but sturdy enough to hit the road in an educational tour of West Virginia high school and community college classrooms. The team will also develop education-oriented radio receivers for use in undergraduate STEM programs at WVU and Yale.
The research is supported by one National Science Foundation grant for $321,000 and another NSF grant in the amount of $281,000.