Observing a Galaxy that Ceased Star Formation over 13 Billion Years Ago
Astronomers have recently detected a galaxy that abruptly halted star formation more than 13 billion years ago. Utilizing the James Webb Space Telescope, a team of researchers led by the University of Cambridge has identified a ‘dead’ galaxy dating back to when the universe was a mere 700 million years old, marking it as the earliest observed galaxy in this state.
The behavior of this galaxy is quite intriguing as it seems to have lived a rapid life, with star formation taking place swiftly and then coming to an abrupt halt, all within a short timespan. This cessation of star formation at such an early stage in the universe’s history is unexpected. The cause behind this galaxy’s ‘quenched’ state remains a mystery, and it is uncertain whether this halt in star formation is temporary or permanent.
These groundbreaking findings, documented in the prestigious journal Nature, hold potential significance in unraveling the enigma surrounding why galaxies cease forming new stars and whether the underlying factors impacting star formation have evolved over billions of years.
Tobias Looser, the lead author of the study from the Kavli Institute for Cosmology, remarked, “The initial few hundred million years of the universe were incredibly active, marked by numerous gas clouds collapsing to give birth to new stars. Galaxies require a rich gas supply for star formation, and in the early universe, it was akin to an limitless feast.”
Co-author Dr. Francesco D’Eugenio also pointed out, “It is only later in the universe’s timeline that we witness galaxies halting star formation, be it due to a black hole or other phenomena. Various factors like a supermassive black hole or feedback from star formation can strip a galaxy of the essential gas needed for the birth of new stars, leading to a rapid cessation of star formation. Conversely, rapid gas consumption by star formation, without immediate replenishment, can result in a galaxy being starved of gas.”
The researchers, however, remain puzzled as to whether any of these scenarios could account for the observations made with the Webb telescope. Professor Roberto Maiolino emphasized, “Historically, our understanding of the early universe has been based on models derived from the present-day universe. But with the capability to delve further back in time, observing galaxies experiencing such swift star formation halting prompts a reevaluation of the models based on the modern universe.”
Through data collected from JADES (JWST Advanced Deep Extragalactic Survey), the astronomers determined that this particular galaxy underwent a brief yet intense phase of star formation lasting between 30 and 90 million years. However, approximately 10 to 20 million years prior to its observation with the Webb telescope, the galaxy’s star formation abruptly ceased.
Looser added, “Events in the early universe seem to occur more rapidly and dramatically, including galaxies transitioning from active star-forming to dormant or quenched states.” While dead galaxies in the early universe have been observed previously, this recent discovery sheds new light on the evolution of galaxies and star formation processes in the cosmos.