Water – a requirement of life as we know it – discovered in a galaxy far, far away

This artist’s performance shows dust continuum and molecular lines of carbon monoxide and water seen in the pair of galaxies known as SPT0311-58. ALMA data reveal abundant amounts of CO and H20 in the larger of the two galaxies, indicating that the molecular universe was moving strongly shortly after the elements were originally forged. Credit: ALMA (ESO / NAOJ / NRAO) / S. Dagnello (NRAO)

New study marks the most distant detection of the necessary element for life as we know it in an ordinary star-forming galaxy.

Water has been discovered in the most massive galaxy in the early universe according to new observations from the Atacama Large Millimeter / submillimeter Array (ALMA). Scientists studying SPT0311-58 found H20 along with carbon monoxide in the galaxy, which is located nearly 12.88 billion light-years from Earth. Detection of these two molecules in abundance suggests that the molecular universe went strong shortly after the elements were forged into early stars. The new research includes the most detailed study of the molecular gas content of a galaxy in the early universe to date and the most remote detection of H20 in an ordinary star-forming galaxy. The research is published in The Astrophysical Journal.

SPT0311-58 actually consists of two galaxies and was first seen by ALMA scientists in 2017 at its location or time in the reionization era. This era took place at a time when the universe was only 780 million years old – about 5 percent of its current age – and the first stars and galaxies were born. Scientists believe that the two galaxies may merge and that their rapid star formation not only uses their gas or star-forming fuel, but that it may eventually evolve the pair into massive elliptical galaxies such as those seen in the local universe.

Animated composite view of SPT0311-58

This animated gif moves through dust continuum and molecular lines of water and carbon monoxide seen in ALMA observations of the pair of early massive galaxies known as SPT0311-58. This gif begins with a composite that combines the dust continuum with molecular lines for H20 and CO. It is followed by the dust continuum seen in red, molecular lines for H 2 O seen in blue, molecular lines for carbon monoxide, CO (10-9) shown in pink and deep blue, CO (7-6) shown in magenta and CO (6-5) shown in purple. Credit: ALMA (ESO / NAOJ / NRAO) / S. Dagnello (NRAO)

“Using high-resolution ALMA molecular gas observations in the pair of galaxies collectively known as SPT0311-58, we detected both water and carbon monoxide molecules in the larger of the two galaxies. In particular, oxygen and carbon are first-generation elements, and in the molecular forms of carbon monoxide and water are the vital ones for life as we know it, “said Sreevani Jarugula, an astronomer at the University of Illinois and lead researcher on the new research.” This galaxy is the most massive galaxy currently known. by high redshift, or the time when the universe was still very young. It has more gas and dust compared to other galaxies in the early universe, giving us plenty of potential opportunities to observe abundant molecules and to better understand how these life-creating elements affected the evolution of the early universe. “

In particular, water is the third most abundant molecule in the universe after molecular hydrogen and carbon monoxide. Previous studies of galaxies in the local and early universe have correlated migratory emissions and distant infrared emissions from dust. “The dust absorbs the ultraviolet radiation from the stars in the galaxy and re-emits it as far-infrared photons,” Jarugula said. “This excites the water molecules further, giving rise to the water discharge that scientists are able to observe. In this case, it helped us detect water emission in this massive galaxy. This correlation could be used to develop water as a trace of star formation. , which could then be applied to galaxies on a cosmological scale. “

Radio display of SPT0311-58

These scientific images show the molecular lines and dust continuum seen in ALMA observations of the pair of early massive galaxies known as SPT0311-58. Left: A composite image that combines the dust continuum with molecular lines for H20 and CO. Right: Dust continuum seen in red (top), H20 molecular line shown in blue (2nd from top), carbon monoxide molecular transitions, CO (6-5) shown in purple (center), CO (7-6) shown in magenta (second from bottom), and CO (10-9) shown in pink and deep blue (bottom). Credit: ALMA (ESO / NAOJ / NRAO) / S. Dagnello (NRAO)

Studying the first galaxies that form in the universe helps scientists better understand the birth, growth and evolution of the universe and everything in it, including the solar system and the Earth. “Early galaxies form stars at a speed thousands of times greater than that The Milky Way, said Jarugula. “Studying the gas and dust content of these early galaxies informs us about their properties, such as how many stars are formed, the rate at which gas converts to stars, how galaxies interact with each other and with the interstellar medium, and more.”

According to Jarugula, there is plenty left to learn about SPT0311-58 and the galaxies of the early universe. “This study not only provides answers to where and how far away water can exist in the universe, but has also given rise to a major question: How did so much gas and dust accumulate to form stars and galaxies so early in the universe? “The answer requires further study of these and similar star-forming galaxies to gain a better understanding of the structural formation and evolution of the early universe.”

“This exciting result, which demonstrates the power of ALMA, adds to a growing collection of observations of the early universe,” said Joe Pesce, astrophysicist and ALMA program director at the National Science Foundation. “These molecules, which are important for life on Earth, are formed as soon as they can, and their observation gives us insight into the basic processes of a universe that is very different from today’s.”

Reference: “Molecular line observations in two dusty star-forming galaxies at z = 6.9” November 3, 2021, The Astrophysical Journal.

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