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10x More Supernovae in Early Universe

From: scitechdaily.com

Exploding Star Supernova Concept

The James Webb Space Telescope has discovered a remarkable number of distant supernovae, providing new insights into the early universe’s structure and expansion. This includes the detection of Type Ia supernovae at unprecedented distances, contributing to our understanding of cosmic distances and the universe’s expansion. Credit: SciTechDaily.com

JADES Transient Survey (Webb NIRCam Image)

The JADES Deep Field uses observations taken by NASA’s James Webb Space Telescope (JWST) as part of the JADES (JWST Advanced Deep Extragalactic Survey) program. A team of astronomers studying JADES data identified about 80 objects (circled in green) that changed in brightness over time. Most of these objects, known as transients, are the result of exploding stars or supernovae. Credit: NASA, ESA, CSA, STScI, JADES Collaboration

Webb Space Telescope Opens New Window on Supernova Science

Peering deeply into the cosmos, NASA’s James Webb Space Telescope is providing scientists with their first detailed glimpse of supernovae from a time when our universe was just a small fraction of its current age. A team using Webb data has identified 10 times more supernovae in the early universe than were previously known. A few of the newfound exploding stars are the most distant examples of their type, including those used to measure the universe’s expansion rate.

“Webb is a supernova discovery machine,” said Christa DeCoursey, a third-year graduate student at the Steward Observatory and the University of Arizona in Tucson. “The sheer number of detections plus the great distances to these supernovae are the two most exciting outcomes from our survey.”

DeCoursey presented these findings in a press conference at the 244th meeting of the American Astronomical Society in Madison, Wisconsin.

Redshifted Light From Distant Galaxies

Credit: NASA, ESA, CSA, Ann Feild (STScI)

‘A Supernova Discovery Machine’

To make these discoveries, the team analyzed imaging data obtained as part of the JWST Advanced Deep Extragalactic Survey (JADES) program. Webb is ideal for finding extremely distant supernovae because their light is stretched into longer wavelengths — a phenomenon known as cosmological redshift. (See image above.)

Prior to Webb’s launch, only a handful of supernovae had been found above a redshift of 2, which corresponds to when the universe was only 3.3 billion years old — just 25% of its current age. The JADES sample contains many supernovae that exploded even further in the past, when the universe was less than 2 billion years old.

Previously, researchers used NASA’s JADES Transients (Webb NIRCam Image)

This mosaic displays three of about 80 transients, or objects of changing brightness, identified in data from the JADES (JWST Advanced Deep Extragalactic Survey) program. Most of the transients are the result of exploding stars or supernovae. By comparing images taken in 2022 and 2023, astronomers could locate supernovae that, from our perspective, recently exploded (like the examples shown in the first two columns), or supernovae that had already exploded and whose light was fading away (third column).
The age of each supernova can be determined from its redshift (designated by ‘z’). The light of the most distant supernova, at a redshift of 3.8, originated when the universe was only 1.7 billion years old. A redshift of 2.845 corresponds to a time 2.3 billion years after the Big Bang. The closest example, at a redshift of 0.655, shows light that left its galaxy about 6 billion years ago, when the universe was just over half its current age.
Credit: NASA, ESA, CSA, STScI, Christa DeCoursey (University of Arizona), JADES Collaboration

“This is really our first sample of what the high-redshift universe looks like for transient science,” said teammate Justin Pierel, a NASA Einstein Fellow at the Space Telescope Science Institute (STScI) in Baltimore, Maryland. “We are trying to identify whether distant supernovae are fundamentally different from or very much like what we see in the nearby universe.”

Pierel and other STScI researchers provided expert analysis to determine which transients were actually supernovae and which were not, because often they looked very similar.

The team identified a number of high-redshift supernovae, including the farthest one ever spectroscopically confirmed, at a redshift of 3.6. Its progenitor star exploded when the universe was only 1.8 billion years old. It is a so-called core-collapse supernova, an explosion of a massive star.

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