Early galaxies may be bigger and more complex than we thought

Early galaxies may be bigger and more complex than we thought

Alma (ESO/NAOJ/NRAO), B. Saxton (NRAO/AUI/NSF)

An artist’s impression showing the previously unknown complexity of the young galaxy A1689-zD1.

Scientists used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the abundance of cold neutral gas in the outer regions of the young galaxy A1689-zD1, as well as thermals from the galaxy’s center.

These results may reveal a key stage in the evolution of galaxies in early galaxies, where young galaxies begin to transform, becoming more and more like their newer, more organized cousins.

The remarks were made during a press conference at the 240th meeting of the American Astronomical Society in Pasadena, California, and will be published in an upcoming issue of astrophysical journal.

A1689-zD1 – a young, active, star-forming galaxy Compared to the Milky Way, it’s slightly less bright and massive—it’s located in the direction of the constellation Virgo, about 13 billion light-years from Earth.

be found Hidden behind galaxy cluster Abell 1689 2007 and confirmed in 2015, thanks to gravitational lensing, which magnifies the brightness of young galaxies by more than 9 times.

Since then, scientists have been studying the Milky Way as a possible analog Evolution of other “normal” galaxies.

This label- normal – is an important distinction that helped researchers divide A1689-zD1’s behavior and features into two groups: typical and unusual, with unusual features mimicking newer, more massive galaxies.

A1689-zD1 in the early universe — just 700 million years after the Big Bang. This is the era when galaxies are just starting to form,” he said. Hollis Adkinsan undergraduate astronomy student at Grinnell College and lead author of the survey.

“What we’re seeing in these observations may help The evolution of what we call normal galaxies, rather than massive galaxies. Most importantly, these processes are ones we previously thought were not applicable to these normal galaxies. “

One of these unusual processes is the production and distribution in the Milky Way fuel for star formationPossibly a lot.

The team used ALMA’s highly sensitive Band 6 receptor to observe carbon halos far beyond the centers of young galaxies.

This could be evidence of ongoing star formation in the same region, or the result of structural disruptions in the early stages of galaxy formation, such as mergers or outflows.

According to Atkins, this is unusual for an early galaxy. “The carbon gas we observe in this galaxy is usually located in the same region as neutral hydrogen gas, which is also where new stars are formed. If this is the case with A1689-zD1, then this galaxy may be much larger than previously thought many.”

“This halo may also be remnants of galactic activity Earlier, mergers, for example, exerted complex gravitational forces on galaxies, resulting in massive ejections of neutral gas at these great distances,” the astronomers added.

“In both cases, the early evolution of this galaxy is likely active and dynamic, and We learned that this could be a common themealthough not observed before, in the formation of the first galaxies,” concluded Akins.

Not only is this discovery unusual, it could have major implications for the study of galaxy evolution, especially as radio observations unravel invisible details at light wavelengths.

Seiji Fujimoto“The emission of carbon gas from A1689-zD1 is much more extensive than observed by the Hubble Space Telescope, which may mean that The first galaxy is not as small as it seems.”

“In fact, if the first galaxies were larger than we previously thought, then great influence on the theory The formation and evolution of galaxies in the early universe,” added Fujimoto.

Led by Atkins, the team also observed an outflow of hot ionized gas—often triggered by violent galactic activity such as supernovae—pushing outward from the center of the galaxy. Given its potentially explosive nature, Flow may be related to carbon halo.

“Flow occurs in result of violencesuch as a supernova explosion – which Blast nearby gaseous matter out of the galaxy – or black holes at the centers of galaxies – have powerful magnetic effects that eject matter in powerful jets,” Atkins said.

“Therefore, the warm current is most likely related to the presence of the cold carbon halo. And that rmore emphasis on importance The multiphase or hot-to-cold nature of the airflow,” he added.

Darlak Watson An associate professor at the Niels Bohr Institute’s Center for Cosmic Dawn and a co-author of the new survey identified in 2015 that A1689-zD1 is a high-redshift galaxy, the most distant known dusty galaxy.

“We’ve seen massive emissions of gaseous halos from galaxies that formed late in the universe, but seeing it in such an early galaxy implies this behavior Common in even the most common galaxies It formed most of the stars in the early universe,” Watson said.

“Understanding how these processes occur in such young galaxies is important for Learn how star formation happens in the early universe,” the astronomer added.

Kirsten KnudsenEvidence of the A1689-zD1 dust continuum was discovered in 2017 by Professor of Astrophysics in the Department of Space, Earth and Environment at Chalmers University of Technology and a co-author of the study. Knudsen highlights the serendipitous role of extreme gravitational lensing in the fabrication process. Every possible discovery is under investigation.

“Given that A1689-zD1 is magnified more than 9 times, we can see key details that are difficult to observe in ordinary observations of such distant galaxies. Ultimately, We see the first galaxy here The universe is very complex, and this galaxy will continue to present new challenges and research results for some time to come,” said the researchers.

doctor. Joe Pesce, NSF’s ALMA program officer, added: “This fascinating ALMA survey adds to a growing body of results that show that things aren’t quite what we expected in the early universe, but are really interesting and Exciting!”

Spectroscopic and infrared observations of A1689-zD1 are planned for January 2023 using the NIRSpec IFU (Integrated Field Unit) and NIRCam instruments on the James Webb Space Telescope.

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The new observations will complement previous Hubble and ALMA data, providing deeper and more complete multi-wavelength observations of young galaxies.

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