The JADES Deep Field uses observations made by NASA’s James Webb Space Telescope (JWST) as part of the JWST Advanced Deep Extragalactic Survey (JADES) program. A team of astronomers studying JADES data identified about 80 objects (circled in green) that change in brightness over time. Most of these objects, known as transients, are the result of exploding stars or supernovae. Before this study, only a few supernovae had been detected above a redshift of 2, which corresponds to a time 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. It includes the most distant one ever confirmed spectroscopically at a redshift of 3.6. Its progenitor star exploded when the universe was only 1.8 billion years old. Courtesy: NASA, ESA, CSA, STScI, JADES Collaboration
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The JADES Deep Field uses observations made by NASA’s James Webb Space Telescope (JWST) as part of the JWST Advanced Deep Extragalactic Survey (JADES) program. A team of astronomers studying JADES data identified about 80 objects (circled in green) that change in brightness over time. Most of these objects, known as transients, are the result of exploding stars or supernovae. Before this study, only a few supernovae had been detected above a redshift of 2, which corresponds to a time 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. It includes the most distant one ever confirmed spectroscopically at a redshift of 3.6. Its progenitor star exploded when the universe was only 1.8 billion years old. Courtesy: NASA, ESA, CSA, STScI, JADES Collaboration
Peering deep into space, NASA’s James Webb Space Telescope is giving scientists their first detailed look at supernovae from when our universe was just a fraction of its current age. A team using Webb data has identified 10 times more supernovae in the early universe than previously known. Some of the newly discovered exploding stars are the most distant examples of their type, including those used to measure the expansion rate of the universe.
“Webb is a supernova discovery machine,” said Krista DeCourcy, a third-year graduate student at the Steward Observatory and the University of Arizona in Tucson. “The sheer number of detections plus the large distances to these supernovae are the two most exciting results of our study.”
DeCoursey presented these findings at a news conference at the 244th meeting of the American Astronomical Society in Madison, Wisconsin.
“Supernova Detection Machine”
To make these discoveries, the team analyzed data from images 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.
Before Webb’s launch, only a few supernovae had been detected above a redshift of 2, which corresponds to a time when the universe was only 3.3 billion years old—only 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 Hubble Space Telescope to see supernovae from when the universe was in its “young adult” stage. With JADES, scientists see supernovae when the universe was in its “teens” or “pre-teens.” In the future, they hope to look back at the “toddler” or “baby” phase of the universe.
To detect supernovae, the team compares multiple images taken one year apart and looks for sources that have disappeared or appeared in those images. Those objects that vary in observed brightness over time are called transients, and supernovae are a type of transients. In total, the JADES Transient Survey Sample team detected about 80 supernovae in a slice of sky only the thickness of a grain of rice held at arm’s length.
“This is really our first sample of what the high-redshift Universe looks like for transient science,” said teammate Justin Pierell, a NASA Einstein Fellow at the Space Telescope Science Institute (STScI) in Baltimore, Maryland. “We’re trying to determine whether distant supernovae are fundamentally different or very similar to what we see in the nearby universe.”
Pierrel and other STScI researchers provided expert analysis to determine which transients were actually supernovae and which were not, because they often looked very similar.
The team identified a number of high-redshift supernovae, including the most distant ever confirmed spectroscopically, at a redshift of 3.6. Its progenitor star exploded when the universe was only 1.8 billion years old. This is the so-called core-collapse supernova, the explosion of a massive star.
This mosaic shows three of about 80 transients, or objects with changing brightness, identified in data from the JWST Advanced Deep Extragalactic Survey (JADES) program. Most 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, have recently exploded (such as the examples shown in the first two columns), or supernovae that have already exploded and whose light disappears (third column). The age of each supernova can be determined by its redshift (denoted ‘z’). The light from 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 the galaxy about 6 billion years ago, when the universe was just over half its current age. Courtesy: NASA, ESA, CSA, STScI, Christa DeCoursey (University of Arizona), JADES Collaboration
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This mosaic shows three of about 80 transients, or objects with changing brightness, identified in data from the JWST Advanced Deep Extragalactic Survey (JADES) program. Most 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, have recently exploded (such as the examples shown in the first two columns), or supernovae that have already exploded and whose light disappears (third column). The age of each supernova can be determined by its redshift (denoted ‘z’). The light from 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 the galaxy about 6 billion years ago, when the universe was just over half its current age. Courtesy: NASA, ESA, CSA, STScI, Christa DeCoursey (University of Arizona), JADES Collaboration
Discovery of distant Type Ia supernovae
Of particular interest to astrophysicists are type Ia supernovae. These exploding stars are so predictably bright that they are used to measure distant cosmic distances and help scientists calculate the expansion rate of the universe. The team identified at least one Type Ia supernova at a redshift of 2.9. Light from this explosion began traveling to us 11.5 billion years ago, when the universe was only 2.3 billion years old. The previous distance record for a spectroscopically confirmed Type Ia supernova was a redshift of 1.95 when the Universe was 3.4 billion years old.
Scientists are eager to analyze Type Ia supernovae at high redshifts to see if they all have the same intrinsic brightness regardless of distance. This is extremely important because if their brightness varied with redshift, they would not be reliable markers for measuring the expansion rate of the universe.
Pierel analyzed this Type Ia supernova, detected at redshift 2.9, to determine if its intrinsic brightness was different than expected. Although this is only the first such object, the results show no evidence that the Type Ia luminosity changes with redshift. More data is needed, but for now, Type Ia supernova-based theories about the universe’s expansion rate and its ultimate fate remain intact. Pierel also presented his findings at the 244th meeting of the American Astronomical Society.
Looking to the future
The early universe was a very different place with extreme environments. Scientists expect to see ancient supernovae that come from stars that contain much less heavy chemical elements than stars like our Sun. Comparing these supernovae to those in the local universe will help astrophysicists understand the mechanisms of star formation and supernova explosion at these early times.
“We’re essentially opening a new window into the transient universe,” said STScI Fellow Matthew Siebert, who led the spectroscopic analysis of the JADES supernovae. “Historically, whenever we’ve done this, we’ve found extremely exciting things — things we didn’t expect.”
“Because Webb is so sensitive, it detects supernovae and other transients almost everywhere it points,” said JADES team member Eiichi Egami, a research professor at the University of Arizona in Tucson. “This is the first significant step toward more extensive studies of supernovae with Webb.”
