Showing posts with label pristine gas clouds. Show all posts
Showing posts with label pristine gas clouds. Show all posts

Wednesday, March 06, 2024

Webb Unlocks Secrets of One of the Most Distant Galaxies Ever Seen

GOODS-North Field (NIRCam Image)
Credits: Image: NASA, ESA, CSA, STScI, Brant Robertson (UC Santa Cruz), Ben Johnson (CfA), Sandro Tacchella (Cambridge), Marcia Rieke (University of Arizona), Daniel Eisenstein (CfA)

Pristine Gas Clump Near GN-z11
Credits: Illustration: NASA, ESA, CSA, Ralf Crawford (STScI)



Looking deeply into space and time, two teams using NASA’s James Webb Space Telescope have studied the exceptionally luminous galaxy GN-z11, which existed when our 13.8 billion-year-old universe was only about 430 million years old.

Initially detected with NASA’s Hubble Space Telescope, this galaxy — one of the youngest and most distant ever observed — is so bright that it is challenging scientists to understand why. Now, GN-z11 is giving up some of its secrets.

Vigorous Black Hole Is Most Distant Ever Found

A team studying GN-z11 with Webb found the first clear evidence that the galaxy is hosting a central, supermassive black hole that is rapidly accreting matter. Their finding makes this the farthest active supermassive black hole spotted to date.

“We found extremely dense gas that is common in the vicinity of supermassive black holes accreting gas,” explained principal investigator Roberto Maiolino of the Cavendish Laboratory and the Kavli Institute of Cosmology at the University of Cambridge in the United Kingdom. “These were the first clear signatures that GN-z11 is hosting a black hole that is gobbling matter.”

Using Webb, the team also found indications of ionized chemical elements typically observed near accreting supermassive black holes. Additionally, they discovered a very powerful wind being expelled by the galaxy. Such high-velocity winds are typically driven by processes associated with vigorously accreting supermassive black holes.

“Webb’s NIRCam (Near-Infrared Camera) has revealed an extended component, tracing the host galaxy, and a central, compact source whose colors are consistent with those of an accretion disk surrounding a black hole,” said investigator Hannah Übler, also of the Cavendish Laboratory and the Kavli Institute.

Together, this evidence shows that GN-z11 hosts a 2-million-solar-mass, supermassive black hole in a very active phase of consuming matter, which is why it's so luminous.

Pristine Gas Clump in GN-z11’s Halo Intrigues Researchers

A second team, also led by Maiolino, used Webb’s NIRSpec (Near-Infrared Spectrograph) to find a gaseous clump of helium in the halo surrounding GN-z11.

“The fact that we don't see anything else beyond helium suggests that this clump must be fairly pristine,” said Maiolino. “This is something that was expected by theory and simulations in the vicinity of particularly massive galaxies from these epochs — that there should be pockets of pristine gas surviving in the halo, and these may collapse and form Population III star clusters.”

Finding the never-before-seen Population III stars — the first generation of stars formed almost entirely from hydrogen and helium — is one of the most important goals of modern astrophysics. These stars are anticipated to be very massive, very luminous, and very hot. Their expected signature is the presence of ionized helium and the absence of chemical elements heavier than helium.

The formation of the first stars and galaxies marks a fundamental shift in cosmic history, during which the universe evolved from a dark and relatively simple state into the highly structured and complex environment we see today.

In future Webb observations, Maiolino, Übler, and their team will explore GN-z11 in greater depth, and they hope to strengthen the case for the Population III stars that may be forming in its halo.

The research on the pristine gas clump in GN-z11’s halo has been accepted for publication by Astronomy & Astrophysics. The results of the study of GN-z11’s black hole were published in the journal Nature on January 17, 2024. The data was obtained as part of the JWST Advanced Deep Extragalactic Survey (JADES), a joint project between the NIRCam and NIRSpec teams.

The James Webb Space Telescope is the world’s premier space science observatory. Webb is solving mysteries in our solar system, looking beyond to distant worlds around other stars, and probing the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency.




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Space Telescope Science Institute, Baltimore, Maryland

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Space Telescope Science Institute, Baltimore, Maryland

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Friday, November 11, 2011

Found: Pristine Gas From The Big Bang

The two pristine gas clouds found by astronomers could sit in one of the filamentary regions visible around galaxies in this and the below image, which are from computer simulations. Credit: Simulation by Ceverino, Dekel & Primack


Kamuela, HI – Two clumps of primordial gas from the dawn of time have been detected in deep space by astronomers using the 10-meter telescopes at the W. M. Keck Observatory.

The gas clouds are too diffuse to form stars and show virtually no signs of containing any “metals,” which is astronomer-speak for all elements heavier than hydrogen and helium – the two simplest and lightest elements in the universe. In fact the only elements astronomers have detected in the clouds are hydrogen and its heavier isotope, deuterium.

The lack of metals strongly suggests that the gases are reservoirs of the pristine material left over from the Big Bang. Because stars fuse atoms to make heavier elements, these gases have never been involved in any star making in the 2 billion years between the Big Bang and their discovery. In other words, they are the remnant gases that are unchanged since they were created in the first few minutes after the Big Bang.

“Despite decades of effort to find anything metal-free in the universe, Nature has previously set a limit to enrichment at no less than one-thousandth that found in the Sun,” said astronomer J. Xavier Prochaska of the University of California Observatories-Lick Observatory, U.C. Santa Cruz. “These clouds are at least 10 times lower than that limit and are the most pristine gas discovered in our universe.”

Prochaska has coauthored a paper reporting on the discovery with Michele Fumagalli of the U.C. Santa Cruz and John O’Meara of Saint Michael’s College in Vermont. The paper is scheduled to be published by the journal Science, on the Science Express website (http://www.sciencexpress.org) on Nov. 10.

“We’ve searched carefully for oxygen, carbon, nitrogen and silicon – the things that are found on Earth and the Sun in abundance,” Fumagalli said. “We don’t find a trace of anything other than hydrogen and deuterium.”

Exactly how they can detect dark, cold, diffuse gas about 12 billion light-years away is a story in itself.

“In this case we actually have to do a bit of a trick,” Prochaska explained. “We study the gas in silhouette.” A more distant quasar provides the light for this. The quasar light shines though the gas and the elements in the gas absorb very specific wavelengths of light, which can only be found by splitting the light into very detailed spectra to reveal the dark lines of missing light.

In other words, said Fumagalli, “All of the analysis is on the light we didn’t get.” The clouds absorb only a small fraction of the quasar light that makes it to Earth. “But the signatures of hydrogen absorption are obvious, so there’s no doubt there’s a lot of gas there.”

The blobs of pristine gas are good news to astronomers because they are confirmation of the theory of what the first elements were and how they were created in the Big Bang. Hydrogen, helium, lithium and boron are the lightest elements on the periodic table of elements and they were all created for the first time in what’s called the Big Bang nucleosynthesis (BBN).

“That theory has been very well tested at Keck as regards to hydrogen and its isotope deuterium,” said O’Meara. “One of the conundrums of that previous work, however, is that the gas also showed at least trace amounts of oxygen and carbon. The clouds that we have discovered are the first to match the full predictions of BBN.”

The discovery also reveals how different the early universe was from today – where it’s very hard to find any place without some “metals” caused by generations of element-building fusion reactors, a.k.a. stars.

“What excites me about this discovery is that there is an almost a range of 1,000,000 in the metallicity in gases at that time in the universe,” said Fumagalli. In other words, there were places like our Solar system – where metals are very abundant – and there were also places very unlike today, where metals were still virtually non-existent and the gases were unchanged since almost the beginning of time.

The W. M. Keck Observatory operates two 10-meter optical/infrared telescopes on the summit of Mauna Kea on the Big Island of Hawaii. The twin telescopes feature a suite of advanced instruments including imagers, multi-object spectrographs, high-resolution spectrographs, integral-field spectroscopy and a world-leading laser guide star adaptive optics system which cancels out much of the interference caused by Earth’s turbulent atmosphere. The Observatory is a private 501(c) 3 non-profit organization and a scientific partnership of the California Institute of Technology, the University of California and NASA.