A University of Manchester astronomer is set to build the most detailed and accurate model of the radio sky ever built, offering new insights into the first stars, galaxies, and possibly new physics.
Thanks to a €2.25M Consolidator Grant from the European Research Council (ERC), UnifySky – a five-year project led by Dr Phil Bull – will combine decades of existing radio observations with new data from a custom-built horn-antenna – named RHINO – to tackle one of cosmology’s biggest challenges.
The “radio sky” refers to the radio waves emitted by objects across the Universe, including pulsars, quasars, and clouds of hydrogen gas. Although invisible to the human eye, these signals carry vital clues about the Universe’s earliest moments, such as how the first stars and galaxies formed. Mapping the radio sky allows astronomers to uncover hidden structures and processes that cannot be seen with traditional optical telescopes. However, progress has been held back by sky maps that are incomplete, inconsistent, or affected by instrumental errors.
“Existing sky maps can be wrong by more than 10%, yet we need errors below 1%,” explained Dr Bull, Reader in Cosmology at the Jodrell Bank Centre for Astrophysics, University of Manchester. “These inaccuracies arise from old, inconsistent data stitched together from many different telescopes. Without improved models, the faint signals from the first stars and galaxies are lost beneath the much stronger radio emission from our own Galaxy.”
To achieve this, the project will combine decades of existing observations with new, precisely calibrated measurements from RHINO. Using advanced statistical techniques implemented in Dr Bull’s world-leading Hydra software, UnifySky will untangle overlapping signals and correct for errors from previous instruments, producing the first fully consistent model of the radio sky.
A key target is the extremely faint 21cm signal emitted by hydrogen in the early Universe, which carries key information about when the first stars and galaxies formed. The improved models will transform the scientific output of major experiments such as the Hydrogen Epoch of Reionization Array (HERA), MeerKAT, and the Square Kilometre Array (SKA), which are seeking to observe the signal.
The project will also revisit two puzzling results reported by the ARCADE-2 instrument and EDGES experiment, which both detected unusual radio signals that some researchers have suggested might hint at new physics. It is not yet clear whether these signals are real or the result of errors in making these tricky measurements.
