Identified a population of extremely distant massive galaxies

Mauro Stefanon
Mauro Stefanon
An international research team with the participation of the University of Valencia has just discovered a population of 6 massive and red galaxies, candidates to form part of the early universe. They are galaxies even older and more massive than most previously identified at those distances. The observations, made using NASA’s JWST telescope, confirm the effectiveness of this space observatory and augur new insights into the beginnings of galaxy formation. The work appears published in the journal Nature.

The discovery of galaxies in the early universe - that is, observed just hundreds of millions of years after the Big Bang - provides astronomers with new insights into the early history of the universe. In particular, by studying their colours, astronomers can reconstruct their main physical properties, such as their stellar mass, their age, or the presence of supermassive black holes in their cores.

An international research team, in which the Department of Astronomy and Astrophysics of the University of Valencia participates, has discovered a population of six galaxies observed at a time between 500 and 800 million years after the Big Bang, and characterised by a colour intrinsically redder than usual in galaxies of the same epoch.

Although these findings still need spectroscopic confirmation - hence they are registered under the name of ’candidates’ - the study already suggests an abundance of ancient stars in these galaxies, which implies that their stellar masses could be up to 100,000 million times superior to that of our Sun. And this even belonging to a cosmic age of intense formation of new stars; that is to say, a time when, it is assumed, the stars were still very young. "The most fascinating thing is that, even if only a fraction of these new objects were to be confirmed, this would already imply masses between 10 and 100 times greater than expected", says Mauro Stefanon, CIDEGENT researcher in the Department of Astronomy and Astrophysics at the University of Valencia and one of the signatories of the article in Nature.

The combination of all these factors - number of galaxies, mass and stellar age - suggests to the research team that star formation in the first galaxies may have been a much more efficient process than previously thought.

"Galaxies observed at these times have generally shown blue colours, indicative of intense new star formation", comments M. Stefanon. "Instead, and unexpectedly, the galaxies now identified exhibit redder colours, which makes them candidates to be part of the list of ancient galaxies in the early universe", adds the scientist.

The James Webb Space Telescope, a new eye on the cosmos

For the purposes of the human eye and from Earth, the population of galaxies identified in this work occupies a small region of the sky equivalent to 1/20 of the surface of the Moon. Approaching the cosmos and achieving the results now obtained by the international team led by astrophysicist Ivo Labbé (Centre for Astrophysics and Supercomputing, Swinburne University of Technology, 8 Melbourne, VIC 3122, Australia) is something that science has to thank the James Webb space telescope (JWST) for.

The result of collaboration between the US (NASA), European (ESA) and Canadian (CSA) space agencies, this observatory is providing the scientific community with its first glimpse of star formation, gas, and dust in galaxies through 98% of the history of the universe, with unprecedented resolution and sensitivity at infrared wavelengths, essential for detecting the most distant galaxies. "The James Webb telescope allows us to capture images with a resolution up to 20 times better and much more sensitive data than those obtained to date with the Hubble (HST) and Spitzer space telescopes. Findings like this confirm the unprecedented capabilities of the space observatory and the effectiveness of studies that use its multiple filters for the identification and characterisation of the first galaxies", says the researcher from the University of Valencia.

Reference:

A population of red, candidate massive galaxies 500’700 Myr after the Big Bang . Ivo Labbé, Pieter van Dokkum, Erica Nelson, Rachel Bezanson, Katherine A. Suess, Joel Leja, Gabriel Brammer, Katherine Whitaker, Elijah Mathews, Mauro Stefanon, Bingjie Wang. Nature 2023. DOI: https://doi.org/10.1038/s41586­’023 -05786-2