Research by Maltese astrophysicist sheds light on distant universe

A research paper by Maltese astrophysicist and University of Malta lecturer Joseph Caruana has been accepted for publication in Monthly Notices of the Royal Astronomical Society – one of the world’s leading peer-reviewed astronomy journals.

Caruana’s paper outlines the discovery of a cluster of 100 galaxies that emit utraviolet light known as Lyman alpha - a spectrum of light that acts as a ‘fingerprint’ and enables astronomers to measure the precise distance to these galaxies.

When studying distant galaxies, Lyman alpha is a much sought-after feature in the spectrum of light. Galaxies that are forming new stars spew out Lyman alpha, so this feature is a tracer of star formation activity in galaxies.

Caruana, who forms part of the Department of Physics and the Institute of Space Sciences & Astronomy (ISSA), explained that there were a number of obstacles that hindered the emergence of this light, and its escape is a key question in the study of galaxies.

Moreover, the distance to these galaxies is so large that during the time that it takes the light to travel to Earth, the universe expands significantly.

“We are looking into the deep past of our universe, observing light that started its journey between 11.6 and 12.8 billion years ago. Just imagine, the universe is 13.8 billion years old,” said Caruana.

To carry out this study, the international team of astronomers, who are affiliated to nine institutions across Europe, used the Multi Unit Spectroscopic Explorer, or  MUSE - a state-of-the-art instrument installed on the Very Large Telescope in Chile. 

This instrument allows astronomers to obtain what is commonly referred to as a datacube, a data structure that provides a 3D view of the universe.

The very complex MUSE instrument (Photo: A. Tudorica/ESO)

“The story of our universe is constructed piece by piece, somewhat akin to assembling a puzzle, where astronomers strive to understand galaxies in their various stages of formation. Building on years of work by the dedicated community of the MUSE consortium, this study represents an example of what can be achieved with this sensitive instrument in the study of distant galaxies,” said Caruana.

Roland Bacon, the principal investigator of the MUSE consortium from the Lyon Centre for Astrophysics Research described MUSE as a unique instrument with incomparable performance which can enable new science in many different areas of astrophysics: from the study of nearby galactic clusters to the most distant galaxies.

“MUSE is complementary to other, much more expensive facilities like the Hubble space telescope. This study improves our understanding of the distant universe and is a good example of what MUSE allows in this competitive field,” said Bacon.

The discovery by Caruana’s team will be presented at an international conference being held in Valletta in October that will be attended by over 100 astronomers from all over the world.

An event for the public will also be held on the evening of October 5 at the Valletta Campus of the University of Malta.