The James Webb Space Telescope has discovered a remarkable number of distant supernovae, providing new insights into the structure and expansion of the early universe. This includes the detection of Type Ia supernovae at unprecedented distances, contributing to our understanding of cosmic distances and the expansion of the universe. Credit: SciTechDaily.com
NASA‘S James Webb Space Telescope appears to excel as a supernova hunter! Thanks to its extreme infrared sensitivity, Webb detects distant supernovae almost everywhere he looks.
Webb is ideal for identifying extremely distant supernovae because of a phenomenon called cosmological redshift, in which light traveling through the universe is stretched into longer wavelengths. Visible light from old supernovae is stretched so much that it ends up in the infrared. Webb’s instruments are tuned to detect infrared light, making them ideal for finding these distant supernovae.
A team has identified ten times more distant supernovae than previously known using data from an in-depth Webb survey of the early universe. This study is the first major step toward more extensive research of ancient supernovae with Webb.
The JADES Deep Field uses observations made by NASA’s James Webb Space Telescope (JWST) as part of the JADES program (JWST Advanced Deep Extragalactic Survey). A team of astronomers studying JADES data identified about 80 objects (circled in green) that changed 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 deep into the cosmos, NASA’s James Webb Space Telescope is offering scientists their first detailed glimpse of supernovae from a time when our universe was only a fraction of its current age. A team using Webb data has identified ten times more supernovae in the early universe than previously known. Some of the newly discovered exploding stars are the most distant examples of their kind, including the stars used to measure the expansion rate of the universe.
“Webb is a supernova discovery machine,” said Christa DeCoursey, a third-year 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 outcomes of our research.”
DeCoursey presented these findings during a press conference at the 244th meeting of the American Astronomical Society in Madison, Wisconsin.
Credit: NASA, ESA, CSA, Ann Feild (STScI)
‘A Supernova Discovery Machine’
To make these discoveries, the team analyzed image 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 to longer wavelengths – a phenomenon known as cosmological redshift. (See image above.)
Before 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 NASAs Hubble Space Telescope to view supernovae when the universe was still in its ‘young adult’ stage. With JADES, scientists see supernovae when the universe was still in its ‘teens’ or ‘pre-teens’. In the future, they hope to revisit the “toddler” or “baby” phase of the universe.
To discover the supernovae, the team compared multiple images taken up to a year apart and looked for sources that disappeared or appeared in those images. These objects whose perceived brightness varies over time are called transients, and supernovae are a type of transient. In total, the JADES Transient Survey Sample team discovered about 80 supernovae in a patch of sky only about the thickness of a grain of rice held at arm’s length.
This mosaic shows three of about 80 transients, or objects of changing brightness, identified in data from the JADES program (JWST Advanced Deep Extragalactic Survey). Most transients are the result of exploding stars or supernovae. By comparing images from 2022 and 2023, astronomers were able to locate supernovae that, from our perspective, had recently exploded (such as the examples in the first two columns), or supernovae that had already exploded and whose light was fading (third column ).
The age of any supernova can be determined by its redshift (denoted ‘z’). The light from the most distant supernova, with a redshift of 3.8, was created 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 example 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 determine whether distant supernovae are fundamentally different from or very similar to what we see in the nearby universe.’
Pierel and other STScI researchers provided expert analysis to determine which transients were actually supernovas and which were not, because they often looked very similar.
The team identified a number of high-redshift supernovae, including the most distant supernova ever confirmed spectroscopically, at a redshift of 3.6. Its precursor 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.
This animation shows the explosion of one white dwarf, an extremely dense remnant of a star that can no longer burn nuclear fuel at its core. In this type Ia supernova, the white dwarf’s gravity steals material away from a nearby stellar companion. When the white dwarf reaches an estimated 1.4 times the current mass of the Sun, it can no longer support its own weight and explodes. Credit: NASA/JPL-Caltech
Discovering distant Type Ia supernovae
Of particular interest to astrophysicists are type Ia supernovae. (See video above.) 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 with a redshift of 2.9. The light from this explosion began traveling toward 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 would like to analyze Type Ia supernovae at high redshifts to see if they all have the same intrinsic brightness regardless of distance. This is crucial because if their brightness varies with redshift, they would not be reliable markers for measuring the expansion rate of the universe.
Pierel analyzed this Type Ia supernova, found at a redshift of 2.9, to determine whether its intrinsic brightness was different than expected. Although this is only the first such object, the results do not indicate that Type Ia’s brightness changes with redshift. More data is needed, but for now the 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 from stars that contain far fewer heavy chemical elements than stars like our Sun. Comparing these supernovae with those in the local universe will help astrophysicists understand the mechanisms of star formation and supernova explosion at these early times.
“We are essentially opening a new window on the ephemeral universe,” says STScI Fellow Matthew Siebert, who is leading the spectroscopic analysis of the JADES supernova. “Historically, whenever we’ve done that, we’ve found extremely exciting things – things we didn’t expect.”
“Because Webb is so sensitive, he finds supernovas and other transients almost everywhere he points,” said JADES team member Eiichi Egami, a research professor at the University of Arizona in Tucson. “This is the first important step toward expanded supernova research with Webb.”
The James Webb Space Telescope is the world’s premier observatory for space science. Webb solves mysteries in our solar system, looks beyond to distant worlds around other stars and investigates the mysterious structures and origins of our universe and our place in it. Webb is an international program led by NASA and its partners ESA (European Space Agency) and CSA (Canadian Space Agency).