UCL Astrophysics Group


First Light

About First Light

Project First Light is an ERC funded research activity whose principal goal is to examine the role that early galaxies played in driving cosmic reionisation. Via deep imaging in blank fields and through gravitationally-lensing clusters, galaxies in the reionisation era are examined spectroscopically using a variety of large ground-based telescopes. Lower redshift analogues of galaxies in the reionisation era are also studied in detail to understand the physical processes by which Lyman continuum photons are produced and can escape into the intergalactic medium. This focused observational activity is supplemented by a theoretical component based on numerical simulations incorporating radiative transfer and the modeling of nebular emission lines as a probe of the nature of the ionising radiation field. The group is actively planning programmes to be undertaken with future facilities including the James Webb Space Telescope - you can read about our accepted proposals on the James Webb Space Telescope here.

Latest News

Cosmic dawn occurred 250 to 350 million years after Big Bang 

24 June 2021

Members of the First Light team claim to have the first convincing evidence for when the first stars and galaxies began to shine. Their analysis indicates that this important moment, known as the “cosmic dawn,” occurred between 250 to 350 million years after the Big Bang. The researchers also calculated that the first galaxies, seen at their birth, will likely be sufficiently luminous to be detected with NASA’s James Webb Telescope due for launch later this year.

Discovering when the cosmic dawn began has been the life’s work of Professor Richard Ellis who commented: “The Holy Grail in observational cosmology has been to look back far enough that one might see the very first generation of stars and galaxies emerging from darkness. We now have convincing evidence of when the universe was first bathed in starlight and  hope to soon make direct observations of this event with the James Webb Space Telescope.”

The scientific article, led by Dr Nicolas Laporte with co-authors Romain Meyer and Guido Roberts-Borsani (all former UCL team members)  and Richard Ellis is being published in the Monthly Notices of the Royal Astronomical Society.

Further details can be found here.

Powerful telescopes probe to great distances, corresponding to ‘look-back times’ of billions of years in the past. The First Light team has studied six galaxies observed when the universe was only 550 million years old, corresponding to only 4% of its present age. However, by measuring the ages of stars in these early galaxies, it is possible to probe even further back in time. The team estimates that such galaxies first ‘switched on’ when the Universe was only 250 to 350 million years old, and the birth of similar systems would be within reach of the James Webb Space Telescope due for launch later this year. 

Credit: Nicolas Laporte / University of Cambridge

James Webb Space Telescope success for First Light group (April 2021)

A photo of the James Webb Space Telescope

The First Light group has had great success in the first cycle of accepted proposals for observing time on the James Webb Space Telescope due for launch in October 2021. 5 proposals were accepted where a group member is Principal Investigator, and an additional 4 proposals accepted with a group member as Co-Investigator. This amounts to a total of 235 hours of observing time.

A list of the accepted proposals can be found here.

In addition to the First Light group’s success described above, it is interesting to note that 16% of all 83 accepted JWST proposals in the ‘Galaxies’ category are led by a current or former postdoctoral researcher or student supervised by Professor Ellis. In 1996 Professor Ellis was the only European-based member of the NASA ‘HST and Beyond’ committee that recommended the construction of what became JWST.

Yuichi Harikane wins prestigious award for young scientists (December 2020)

Yuichi Harikane
Congratulations to Yuichi Harikane (Honorary Researcher with the First Light team), who has won an Inoue Research Encouragement Award for Young Scientists from the Inoue Foundation for Science. This prestigious award is given to researchers under the age of 37 who have obtained a doctoral degree in the field of science and engineering in the last three years.



Richard Ellis awarded the Michael Faraday Gold Medal and Prize by Institute of Physics (November 2020)

Richard Ellis is awarded the Faraday Gold Medal
The Institute of Physics have awarded Richard Ellis the Michael Faraday Gold Medal and Prize, in recognition of over 35 years of pioneering contributions in faint-object astronomy. In awarding this honour, the IoP noted Richard's relentless efforts to push to earlier epochs through faint-object spectroscopy and the use of gravitational lensing, which have inspired generations of young observers who follow in his path. 


Important contribution to understanding when the first galaxies appeared in the Universe 

In May 2018, our team made an important contribution towards astronomers' understanding of the timescales during which the first galaxies appeared in the Universe, by studying a galaxy formed 250 million years after the Big Bang. These results come from observations carried out with the ALMA observatory and the Very Large Telescope.

Significant breakthrough in understanding the early formation of stars 

In March 2017, our team made a significant breakthrough in understanding the early formation of stars in the galaxy when the universe  was about 4% old.  This important breakthrough was reported globally and was the result of our dedicated research into understanding our universe.


Our project has seen a number of papers published, which are available on UCL Open Access and via our website.

A popular summary of our progress was published in EU Research.

About the Team

The team is led by Professor Richard Ellis, and supported by both Research Associates and PhD students.

There are strong collaborative links with research groups at the Royal Observatory Edinburgh, Caltech, the University of Arizona, University of California, Santa Cruz and the University of Tokyo. Please see our First Light Team page for more information on the team.

First Light group photo, UCL, October 2018 (from L-R: Rebecca Martin, Romain Meyer, Koki Kakiichi, Guido Roberts-Borsani, Richard Ellis, Kiana Kade, Sarah Bosman, Nicolas Laporte)