Webb reveals farthest known galaxy – ‘most important extragalactic discovery to date’

Astronomers use NASA‘s James Webb Space Telescope They discovered the oldest and most distant galaxies known, dating back only 300 million years the great explosionIt is a major milestone in understanding the early stages of the universe.

An international team of astronomers has announced the discovery of the two oldest and most distant confirmed galaxies to date, dating back only 300 million years after the Big Bang. This important discovery, made using NASA’s James Webb Space Telescope (JWST), represents a major milestone in the study of the early universe. These galaxies were discovered by JWST’s Advanced Galactic Deep Extraterrestrial Survey (JADES) team, co-led by astronomer Brant Robertson of the University of California, Santa Cruz.

“This discovery is completely unexpected and will likely be viewed as the JWST’s most important extragalactic discovery to date,” said Robertson, professor of astronomy and astrophysics and member of the JADES steering committee. He is the lead author of the first of three papers dealing with different aspects of the discovery.

In one paper, the authors concluded: “This demonstrates the direct impact that new JWST observations can have on our knowledge of the distant universe. With clusters of high-redshift galaxies now forming less than 300 million years after the Big Bang, we have expanded our access to the cosmic past by 40% during the first 18 months of JWST operations.

Redshift refers to an effect caused by the expansion of the universe, where the wavelength of light from distant galaxies is stretched as it travels. In these newly discovered galaxies, the effect is intense, extending by a factor of 15, shifting even the galaxies’ ultraviolet light to infrared wavelengths where only the James Webb Space Telescope can see.

Scientists used the Near Infrared Spectrometer (NIRSpec) of NASA’s James Webb Space Telescope to obtain a spectrum of the distant galaxy JADES-GS-z14-0 in order to precisely measure its redshift and thus determine its age. The redshift can be determined from the location of the critical wavelength known as the Lyman-alpha fraction. This galaxy dates back less than 300 million years after the Big Bang. Image source: NASA, ESA, CSA, Joseph Olmstead (STScI), S. Cargnani (Scuola Normale Superiore), JADES collaboration

Chasing early galaxies

Modern theory holds that galaxies evolve in special regions where gravity concentrates cosmic gas and dark matter into dense clumps known as “halos.” These halos evolved rapidly in the early universe, merging to form massive clumps of matter. This rapid evolution is why astronomers are so keen to find older galaxies: every little increment moves our eyes back to a less evolved period, when brighter galaxies were more distinct and unusual.

The two newly discovered galaxies were found in a region close to the Hubble Extreme Deep Field, and this was confirmed through spectroscopic analysis. In keeping with the collaboration’s standard naming practices, the galaxies are now known as JADES-GS-z14-0 and JADES-GS-z14-1, the former being the more distant of the two.

In addition to being the new distance record holder, the JADES-GS-z14-0 is big and bright. JWST measures the galaxy with a diameter of more than 1,600 light-years. Many of the brightest galaxies produce the bulk of their light through gas falling into a massive galaxy Black hole, quasar production. But the team says the large size of JADES-GS-z14-0 means the light must be produced by young stars.

Deeply hidden gems

However, the massive galaxy was a mystery to the JADES team when they first discovered it more than a year ago, as it appears close enough in the sky to a foreground galaxy that they couldn’t be sure the two weren’t neighbors. But in October 2023, the JADES team conducted deeper imaging — five full days using the JWST near-infrared camera in just one field — to form the “JADES Asset Field.” With the use of filters designed to better isolate early galaxies, confidence increased that JADES-GS-z14-0 was indeed very distant.

In addition, the galaxy happened to fall into a region where the team performed ultra-deep imaging with the JWST Mid-InfraRed instrument. These combined imaging results convinced the team to include the galaxy in what was planned to be JADES’ summit observation, a 75-hour campaign to perform spectroscopic analysis on faint early galaxies. Spectroscopic analysis confirmed their hopes that JADES-GS-z14-0 was indeed a record-breaking galaxy, and that the faint candidate galaxy JADES-GS-z14-1 was almost equally distant.

A new era in cosmic exploration

The combination of high luminosity and stellar origin makes JADES-GS-z14-0 the most outstanding evidence yet of the rapid formation of large, massive galaxies in the early Universe. “We could have detected this galaxy even if it were 10 times fainter, which means we could see other examples in the early universe — perhaps within the first 200 million years,” Robertson said. “This galaxy is truly a gem, and points to more hidden treasures in the early universe.”

Robertson’s paper, “Early galaxies in the JADES origins field: a function of luminosity and cosmic star formation rate density 300 million years after the Big Bang,” has been accepted for publication in the journal Astrophysical Journal.

Reference: “Early Galaxies in the JADES Origins Field: Luminosity and Density Function of the Cosmic Star Formation Rate 300 Ma After the Big Bang” by Brant Robertson, Benjamin D. William M. Baker, Andrew J. Bunker, Stefano Cargnani, Courtney Carrera, Philip A. Cargill, Stephane Charlot, Jacopo Chevallard, Mirko Curti, Emma Curtis Lake, Francesco DiEugenio, Ichi Egami, Ryan Hausen, Jacob M. Hilton. , Peter Jacobsen, Ziyuan Ji, Gareth C. Jones, Roberto Maiolino, Michael V. Maceda, Erika Nilsson, Pablo G. Pérez Gonzalez, David Puskas, Marcia Ricci, Rinsky Smit, Vengo Sun, Hanna Opler, Lily Witler, Cristina C. Williams, Christopher N. A. Wilmer, Chris Willott, Joris Wittstock, accepted. Astrophysical Journal.
arXiv:2312.10033

The James Webb Space Telescope is an international program led by NASA with its partner the European Space Agency (ESA).European Space Agency) and CSA (Canadian Space Agency).