Work begins on building the most accurate map of the radio sky ever made

Tanya Weaver Wed 10 Dec 2025

Collected at: https://eandt.theiet.org/2025/12/10/work-begins-building-most-accurate-map-radio-sky-ever-made

A detailed new model of the ‘radio sky’ could offer fresh insights into the first stars and galaxies and point to new discoveries in physics, according to researchers at the University of Manchester.

UnifySky, a five-year research project based at the university, has received €2.25m in funding from the European Research Council. The project aims to combine decades of existing radio observations with new data from a custom-built horn antenna telescope – RHINO – to create a single, consistent map of the ‘radio sky’.

The radio sky refers to the radio waves emitted by objects across the universe, including pulsars, quasars and clouds of hydrogen gas. Many of these objects are invisible in optical light to traditional telescopes, but mapping the universe in radio-wave frequencies reveals these hidden features. 

While radio sky maps already exist, they are often incomplete, inconsistent or affected by instrumental errors.

Phil Bull, reader in cosmology at the Jodrell Bank Centre for Astrophysics at the University of Manchester, and leader of the project, said: “Existing sky maps can be wrong by more than 10%, yet we need errors below 1%. 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 create a consistent model of the radio sky, the project will combine decades of existing observations with new, precisely calibrated measurements from the RHINO telescope. Located at the Jodrell Bank Observatory, RHINO will be about the size of a semi-detached house, Bull said. 

These measurements will be fed into advanced statistical modelling software developed in-house by Bull and his team. 

A key target is to improve measurements of 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 hope is that results will give new insights into the formation of early structures and the effects of dark energy.

The project will also revisit two puzzling results reported by ARCADE 2 – a Nasa balloon-borne radio instrument – and the EDGES experiment, a ground-based radio antenna located in Western Australia. Both these experiments detected unusual radio signals from the universe’s early history, which some researchers have suggested might hint at a new physics. However, the results remain controversial as it is difficult to separate from foreground radio noise and instrumental effects.