Undergraduate researcher captures young galaxy’s ‘coming of age’ and finds evidence early galaxies could be bigger and more complex than we thought

Scientists using the Atacama Large Millimeter/submillimeter Array (ALMA)— an international observatory cooperated by the United States national science foundationit is National Radio Astronomy Observatory (NRAO)—observed a significant amount of cold neutral gas in the outer regions of the young galaxyGalaxyA large body of gas, dust, stars and their companions (planets, asteroids, moons, etc.) held together by their mutual gravitational attraction. They are grouped into three main categories: spiral galaxies, elliptical galaxies and irregular galaxies. (see below) Another class of galaxies are Peculiar Galaxies, which are thought to be distorted versions of normal galaxies. A1689-zD1, as well as hot gas outflows from the center of the galaxy. These findings may shed light on a critical stage in galactic evolution for early galaxies, where young galaxies begin the transformation to increasingly resemble their later, more structured cousins. The sightings were presented today at a press conference at the 240th meeting of the American Astronomical Society (AAS) in Pasadena, California, and will be published in an upcoming issue of The Astrophysical Journal (ApJ).

A1689-zD1, a young, active, star-forming galaxy slightly less luminous and less massive than the Milky Way, is located about 13 billion Light yearsLight yearsThe distance traveled by light in a year in a vacuum. A light year is approximately six trillion kilometers. away from Earth in the constellation Virgo cluster. It was discovered hidden behind the galaxy cluster Abell 1689 in 2007 and confirmed in 2015 thanks to the gravitational lens, which boosted the brightness of the young galaxy by more than 9x. Since then, scientists have continued to study the galaxy as a possible analogue of the evolution of other “normal” galaxies. This label – normal – is an important distinction that helped researchers divide the behaviors and characteristics of A1689-zD1 into two categories: typical and unusual, with unusual characteristics mimicking those of newer, more massive galaxies.

“A1689-zD1 is located in the very first Universe, only 700 million years after the Big Bang. This is the era when galaxies were just beginning to form,” said Hollis Akins, an undergraduate student in astronomy at Grinnell College and lead author of the research. “What we see in these new observations is evidence of processes that may contribute to the evolution of what we call normal galaxies as opposed to massive galaxies. More importantly, these processes are ones we didn’t previously think applied to these normal galaxies. »

One such unusual process is the galaxy’s production and distribution of star-forming fuel, and potentially a large amount of it. The team used ALMA’s highly sensitive Band 6 receiver to focus on a halo of carbon dioxide that extends far beyond the center of the young galaxy. This could be evidence of continued star formation in the same region or the result of structural disturbances, such as mergers or exits, in the early stages of galaxy formation.

According to Akins, this is unusual for early galaxies. “The carbon dioxide we have observed in this galaxy is generally found in the same regions as neutral hydrogen gas, which is also where new stars tend to form. If this is the case with A1689-zD1 , the galaxy is likely much larger than previously thought.It’s also possible that this halo is a remnant of earlier galactic activity, such as mergers that exerted complex gravitational forces on the galaxy leading to the ejection of a large amount of neutral gas over these great distances. In both cases, the early evolution of this galaxy was probably active and dynamic, and we learn that this may be a common, albeit previously unobserved, theme in the formation of the first galaxies.

More than rare, this discovery could have important implications for the study of galactic evolution, especially when radio observations reveal details invisible to optical wavelengths. Seiji Fujimoto, postdoctoral researcher at the Cosmic Dawn Center of the Niels Bohr Institute, and co-author of the research, said: “The emission of carbon dioxide in A1689-zD1 is much more extensive than what has been observed with the Hubble Space Telescope, and that could mean the first galaxies aren’t as small as they seem. If, in fact, the first galaxies are larger than we previously thought, it would have a major impact on the theory of galaxy formation and evolution in the early Universe.

Led by Akins, the team also observed outflows of hot, ionized gases – usually caused by violent galactic activity like supernovae – pushing outward from the center of the galaxy. It is possible, given their potentially explosive nature, that the flows have something to do with the carbon halo. “Outflows occur as a result of violent activity, such as the explosion of supernovae – which blast nearby gaseous matter out of the galaxy – or black holes at the center of galaxies – which have powerful magnetic effects which can eject material in powerful jets. For this reason, there is a strong possibility that the warm flows have something to do with the presence of the cold carbon halo,” Akins said. importance of the multiphase, or hot to cold, nature of the outgoing gas.”

Darach Watson, associate professor at the Cosmic Dawn Center at the Niels Bohr Institute, and co-author of the new research confirmed A1689-zD1 as a high redshift galaxy in 2015making it the most distant dusty galaxy known. OI have seen this type of extended gas halo emission from galaxies that formed later in the Universe, but to see it in such an old galaxy means that this type of behavior is universal even in smaller galaxies that formed most stars in the early Universe. Understanding how these processes occurred in such a young galaxy is essential to understanding how star formation occurred in the early Universe.

Kirsten Knudsen, professor of astrophysics in the Department of Space, Earth and Environment at Chalmers University of Technology, and co-author of the research found evidence of the dust continuum of A1689-zD1 in 2017. Knudsen emphasized the fortuitous role of extreme gravitational lensing in making possible every new discovery in research. “Because A1689-zD1 is magnified more than nine times, we can see critical details that are otherwise difficult to observe in ordinary observations of galaxies this far away. Ultimately, what we see here is that the early galaxies in the Universe were very complex, and this galaxy will continue to present new challenges and research findings for some time to come.

Dr. Joe Pesce, NSF Program Manager for ALMA, added: “This fascinating research from ALMA adds to a growing body of evidence indicating that things are not quite as we expected in the Primitive universe, but they are nevertheless really interesting and exciting!”

Spectroscopy and infrared observations of A1689-zD1 are scheduled for January 2023, using the NIRSpec Integral Field Unit (IFU) and NIRCam on the James Webb Space Telescope. The new observations will complement previous HST and ALMA data, providing a deeper and more comprehensive multi-wavelength look at the young galaxy.

Resource

“ALMA Reveals Extensive Cool, Hot Ionized Gas in a Typical Star-Forming Galaxy at z=7.13”, Akins et al, The Journal of Astrophysics.

Access and registration of the press conference

Tuesday, June 14, 2022 at 2:15 p.m. PT – Galactic Neighbors, ALMA Insights, and a Record Star

“ALMA Reveals Extensive Fluxes of Cold Gas and Hot Ionization in a Distant Star-Forming Galaxy”

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The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership between the European Organization for Astronomical Research in the Southern Hemisphere (ESO), the US National Science Foundation (NSF) and the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Republic of Chile. ALMA is funded by ESO on behalf of its Member States, by NSF in cooperation with the National Research Council of Canada (NRC) and the Ministry of Science and Technology (MOST), and by NINS in cooperation with Academia Sinica (AS) in Taiwan. and the Korea Institute of Astronomy and Space Science (KASI).

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