NASA’s Webb to discover the riches of the early universe

NASA’s Webb to discover the riches of the early universe

NASA's Webb to discover the riches of the early universe

This image shows where the James Webb Space Telescope will observe the sky in the Hubble Ultra Deep Field, which consists of two fields. The Next Generation Deep Extragalactic Exploratory Public Inquiry (NGDEEP), led by Steven L. Finkelstein, will point Webb’s Near Infrared Imager and Slitless Spectrograph (NIRISS) at the Hubble Ultra Deep primary field (in orange) and the Webb’s near infrared. Camera (NIRCam) on the parallel field (in red). The program led by Michael Maseda will observe the primary field (in blue) using Webb’s Near Infrared Spectrograph (NIRSpec). Credit: SCIENCE: NASA, ESA, Anton M. Koekemoer (STScI) ILLUSTRATION: Alyssa Pagan (STScI)

For decades, telescopes have helped us capture light from galaxies that formed up to 400 million years after the big bang, incredibly early in the context of the 13.8 billion year history of the planet. ‘universe. But what were galaxies like that existed even earlier, when the universe was semi-transparent at the start of a period known as the Age of Reionization? NASA’s next flagship observatory, the James Webb Space Telescope, is poised to add new riches to our wealth of knowledge, not only capturing images of galaxies that existed as early as the first hundreds of millions of years later. the big bang, but also giving us detailed data called spectra. Thanks to Webb’s observations, researchers will for the first time be able to tell us about the make-up and makeup of individual galaxies in the early universe.

The Next Generation Deep Extragalactic Exploratory Public Investigation (NGDEEP), co-led by Steven L. Finkelstein, associate professor at the University of Texas at Austin, will target the same two regions that make up the Hubble Ultra Deep Field – locations in the Fornax constellation where Hubble spent more than 11 days taking deep exposures. To produce its observations, the Hubble Space Telescope simultaneously targeted nearby areas of the sky with two instruments – slightly offset from each other – known as the primary and parallel field. “We have the same advantage with Webb,” Finkelstein explained. “We are using two scientific instruments at once, and they will observe continuously.” They will point Webb’s Near Infrared Imager and Slitless Spectrograph (NIRISS) at the main Hubble Ultra Deep Field, and Webb’s Near Infrared Camera (NIRCam) at the parallel field, getting twice as much ‘money’ for their telescope time.

For imaging with NIRCam, they will observe for more than 125 hours. With each passing minute, they will get more and more information from deeper and deeper into the universe. What are they looking for ? Some of the first galaxies that formed. “We have very good indications from Hubble that there are galaxies in place at some point 400 million years after the big bang,” Finkelstein said. “The ones we see with Hubble are quite large and very bright. It’s highly likely that there are smaller, fainter galaxies that formed even earlier and are waiting to be discovered.”

This program will use only about a third of the time that Hubble has spent on similar surveys to date. Why? This is partly because Webb’s instruments were designed to capture infrared light. As light travels through space towards us, it expands into longer and redder wavelengths due to the expansion of the universe. “Webb will help us push all the boundaries,” said Jennifer Lotz, co-investigator on the proposal and director of the Gemini Observatory, part of the National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory (NOIRLab). “And we will release the data immediately for the benefit of all researchers.”

These researchers will also focus on identifying the metal content in each galaxy, especially in smaller and darker galaxies that have not yet been examined in depth, especially with the spectra provided by the NIRISS instrument. by Webb. “One of the fundamental ways to track evolution over cosmic time is the amount of metals present in a galaxy,” explained Danielle Berg, assistant professor at the University of Texas at Austin and co-investigator on the proposal. At the beginning of the universe, there was only hydrogen and helium. New elements were formed by successive generations of stars. By cataloging the contents of each galaxy, researchers will be able to accurately trace when various elements existed and update models that project how galaxies evolved in the early universe.

Take a journey through time and space to the beginning of the universe with NASA’s James Webb Space Telescope. How will Webb reveal the first unseen galaxies? What are astronomers looking for? Find out the answers to these questions and more with this video. Credit: NASA, ESA, CSA, Danielle Kirshenblat (STScI)

Peel off new layers

Another program, led by University of Wisconsin-Madison assistant professor Michael Maseda, will examine the Hubble Ultra Deep primary field using Webb’s Near Infrared Spectrograph (NIRSpec) microshutter array. This instrument returns spectra for specific objects based on the miniature shutters the researchers open. “These galaxies existed for the first billion years of the universe’s history, about which we have very little information so far,” Maseda explained. “Webb will provide the first large sample that will give us the chance to understand them in detail.”

We know that these galaxies exist thanks to the extensive observations this team has made – together with an international research team – with the ground-based Very Large Telescope’s Multi Unit Spectroscopic Explorer (MUSE) instrument. Although MUSE is the “scout”, identifying smaller and fainter galaxies in this deep field, Webb will be the first telescope to fully characterize their chemical compositions.

These extremely distant galaxies have important implications for our understanding of galaxy formation in the early universe. “Webb will open up a new space of discovery,” explained Anna Feltre, researcher at the National Institute of Astrophysics in Italy and co-researcher. “His data will help us know precisely what happens when a galaxy forms, including what metals they contain, how fast they are growing and whether they already have black holes.”

This research will be conducted under Webb’s General Observer (GO) programs, which are competitively selected using anonymous double review, the same system that is used to allocate time on the Hubble Space Telescope.

First color science images from the Webb Telescope arrive in July

Provided by NASA’s Goddard Space Flight Center

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