In the ancient galactic city found a mysteriously high proportion of dead galaxies – unlike all other known protoscopes

Impressions of this artist reflect the formation of a cluster of galaxies in the early universe. Galaxies vigorously form new stars and interact with each other. Such a scene is very reminiscent of the Web of the Web (formally known as MRC 1138-262) and its surroundings, which is one of the most studied protoscopies. Credit: ESO / M. Kornmesser

Why cluster galaxies differ from galaxies in all other known protoscopes remains a mystery, says a team led by UC Riverside.

An international team of astronomers led by researchers from the University of California at Riverside has discovered an unusual massive cluster of young galaxies forming in the early universe. The newly discovered growing galactic metropolis, called MAGAZ3NE J095924 + 022537, is a newborn cluster of galaxies, or protoscopy, consisting of at least 38 member galaxies and located about 11.8 billion light-years from Earth.

Clusters of galaxies grow over time under gravity and in the modern universe may contain hundreds and even thousands of galaxies, as well as hot gas and dark matter. Over time, their galaxies burn available fuel and transform from star-forming galaxies into red and dead galaxies.

“In the early universe, all the protoscopes discovered so far are full of energetic star-forming galaxies,” said Ian McConaughey, a graduate student in physics and astronomy at the University of California, Riverside and lead author of research published in Astrophysical Journal. “But unbelievably, but unlike all the other protoscopes found in this era, many galaxies in MAGAZ3NE J0959 seem to have already stopped forming stars.”

Co-author Gillian Wilson, a professor of physics and astronomy at UCR, where McConaughey works, said J0959 was found in a survey “Massive Ancient Galaxies at Z> 3 NEar-infrared” or MAGAZ3NE, designed to detect and study their ultramassive galaxies. .

Protocol cluster MAGAZ3NE J095924 + 022537

In the early universe, all previously discovered distant protoscopes, such as the “Web” (left: the impression of the artist), full of galaxies that vigorously form stars. In contrast, the recently discovered protocol cluster “MAGAZ3NE J095924 + 022537” contains a large proportion of red and dead galaxies, such as the neighboring cluster “Coma” (right). The discovery of an ancient cluster containing galaxies resembling those found in modern clusters came as a huge surprise. Author: Spiderweb: M. Kornmesser / ESO; Coma: Ras Carroll, Robert Handler and Bob Franke / Dan Zovada Memorial Observatory

“We see this protocol as it was when the universe was less than 2 billion years old,” she said. “It’s as if you took a cluster like Coma, the closest rich cluster of galaxies to Earth, and dumped it in the early universe.”

Co-author Benjamin Forrest, a former graduate student at Wilson Lab who is now based at Davis College in California, explained that at the center of MAGAZ3NE J0959 is an ultramassive galaxy that has already formed a mass of more than 200 billion suns.

“Why this ultramassive galaxy and so many of its neighbors formed most of its stars and then became inactive when the universe was still so young, unlike other known protoscopes of the same time, remains a big mystery,” he said. “Why its galaxies are so unlike the galaxies of all the other known protoscopes and so similar to the galaxies in Coma remains a complete mystery.”

Forrest added that the MAGAZ3NE J0959 was discovered from the ground, but the emergence of new powerful features such as the recently launched[{” attribute=””>James Webb Space Telescope, should soon reveal whether there are other protoclusters like MAGAZ3NE J0959 packed with dead galaxies waiting to be found in the early universe.

“Should such protoclusters be found in large numbers, it would mean that the current paradigm of protocluster formation would require a major revision,” Forrest said. “A new scenario of protoclusters existing in a diversity of states in the early universe would have to be adopted. With many member galaxies quenching in the first two billion years, this would almost certainly pose significant challenges for current models of galaxy simulation.”

The team used spectroscopic observations from the W. M. Keck Observatory’s Multi-Object Spectrograph for Infrared Exploration, or MOSFIRE, to make detailed measurements of MAGAZ3NE J0959 and precisely quantify its distances.

Closely associated to the question of how ultramassive galaxies form is the question of the environment in which they form, for example, are they always found in overdense environments like protoclusters, or can they also form in isolation? Next, the team plans to study the neighborhood of all other ultramassive galaxies in the MAGAZ3NE survey to answer this question.

Reference: “Spectroscopic Confirmation of a Protocluster at z = 3.37 with a High Fraction of Quiescent Galaxies” by Ian McConachie, Gillian Wilson, Ben Forrest, Z. Cemile Marsan, Adam Muzzin, M. C. Cooper, Marianna Annunziatella, Danilo Marchesini, Jeffrey C. C. Chan, Percy Gomez, Mohamed H. Abdullah, Paolo Saracco and Julie Nantais, 9 February 2022, The Astrophysical Journal.
DOI: 10.3847/1538-4357/ac2b9f

Other researchers involved in the study are Cemile Marsan and Adam Muzzin of York University, Canada; Michael Cooper of UC Irvine; Marianna Annunziatella and Danilo Marchesini of Tufts University; Jeffrey Chan and Mohamed Abdullah of UCR; Percy Gomez of Keck Observatory; Paolo Saracco of Astronomical Observatory of Brera, Italy; Julie Nantais of Andrés Bello National University, Santiago, Chile.

The study was supported by grants from the National Science Foundation and NASA. In the ancient galactic city found a mysteriously high proportion of dead galaxies – unlike all other known protoscopes

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