Aaron Parsons
University of California-Berkeley, CA·Astronomy & Astrophysics
After the Big Bang, the universe was filled with hydrogen gas. Over its first billion years, that gas gave rise to the first stars, galaxies and black holes.
- Fields
Astronomy & Astrophysics
Physics
- Topics
cosmic dawn
epoch of reionization
EoR
- Grants
- 1 known grant, last ended Sep 2026
What they work on
- Measure the redshifted 21-cm radio signal from neutral hydrogen, emitted at a rest frequency of 1420 MHz, across 50–250 MHz using the HERA array of 350 dish antennas, to trace the universe from the Cosmic Dawn to reionization.
- Separate the faint hydrogen signal from much brighter synchrotron emission from our galaxy, which changes smoothly with frequency, by using the hydrogen signal's distinct spectral structure.
- Determine the reionization fraction, the share of intergalactic hydrogen turned into plasma, over time, to test how the first stars and galaxies shaped the early universe.
More about the research
Very little has been observed from the "Cosmic Dawn," when the universe was about 100 to 1,000 million years old and the first stars formed. Energy from those stars and their supernova explosions first heated and then ionized the hydrogen between galaxies, turning it into a plasma. This turning point is called the Epoch of Reionization. Measuring it would connect the well-measured early universe to the galaxies seen today.
Why it matters
This is basic science. The work could fill a major observational gap in the history of the universe: how the first stars and galaxies heated and ionized the hydrogen around them. Measuring when and how fast reionization happened could inform models of how early structure from the Big Bang grew into today's galaxies and black holes. It also connects the precisely measured parameters of cosmology to what astronomers observe in the nearby universe.
Known grants
From NIH and NSF research grants. Labs often have other funding we can't see.
Closest labs
Kieran Cleary
California Institute of Technology, CA·Astronomy & Astrophysics
Build a duplicate of the COMAP Pathfinder receiver and use it to survey the carbon monoxide (CO) line across the sky through line intensity mapping, which measures the combined glow of many galaxies.
Andrew Harris
University of Maryland, MD·Astronomy & Astrophysics
Duplicate the existing COMAP Pathfinder receiver and use it to carry out a sky survey of redshifted carbon monoxide (CO) emission by line intensity mapping.
Laura Newburgh
Yale University, CT·Astronomy & Astrophysics
Develop modeling frameworks and analysis pipelines for cross-correlating CHIME 21cm hydrogen maps with galaxy surveys, and integrate improved models of the telescope beam into the analysis.
The school
University of California-Berkeley: 46 labs on PI Pages, $1.1B a year on research, 825 research doctorates a year.
Reach out
A start for your email. Fill in the brackets.