'Web' discovers 10 times more supernovae in the early universe than were previously known
NASA's James Webb Space Telescope excels as a supernova hunter. Webb detects distant supernovae almost everywhere it looks thanks to its extreme infrared sensitivity.
'Web' is ideal for detecting very distant supernovae because of a phenomenon called "cosmological redshift", in which light traveling through the universe is stretched to longer wavelengths. The visible light from early supernovae is stretched so far that it reaches the infrared range. Webb's instruments are tuned to pick up infrared light, making it ideal for finding these distant supernovae.
The research team identified 10 times more distant supernovae than previously known using data from the Deep Hubble Survey of the Early Universe. This study is the first significant step towards more extensive surveys of early supernovae with 'Web'.
The Webb Space Telescope opens a new window on the science of supernovae
Looking deep into the universe, 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 fraction of its current age. The research team that used 'Web' data, identified 10 times more supernovae in the early universe than were previously known. Some of the newly exploding stars are the most distant examples of their kind, including those used to measure the expansion rate of the universe.
"'Webb' is a supernova detector," said Christa DeCorsi, a third-year PhD student at the Stewart Observatory and the University of Arizona in Tucson. "The sheer number of detections in addition to the great distances to these supernovae are the two most exciting findings from our survey."
DeCourcy presented these findings at a press conference at the 244th meeting of the American Astronomical Society in Madison, Wisconsin.
'Supernova Discovery Machine'
To make these discoveries, the team analyzed imaging data collected as part of the JADES (JWST Advanced Deep Survey) program. 'Web' is ideal for finding very distant supernovae because their light is stretched to longer wavelengths - a phenomenon called "cosmological redshift".
Before Webb's launch, only a few supernovae had been found at a redshift above 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 more in the past, when the universe was less than 2 billion years old.
In the past, researchers used NASA's Hubble Space Telescope to observe supernovae from a time when the universe was in its "young adulthood". With JADES, scientists see supernovae when the universe was in the "pubescent" or "pre-pubescent" phase. In the future, they hope to look back to the "childhood phase" or infancy 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 that change in their observed brightness over time are called transients, and supernovae are a type of transient. In all, the team modeling the JADES transient survey discovered about 80 supernovae in a patch of sky the thickness of a grain of rice held at hand.
The age of the supernova is determined by its redshift (marked as 'z'). The light of the most distant supernova, at a redshift of 3.8, arose when the universe was only 1.7 billion years old. A redshift of 2.845 corresponds to a time of 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 DeCorsi (University of Arizona), JADES Collaboration
"This is really our first glimpse of what the universe at high redshift looks like for transient science," said team member Justin Fairl, a researcher with NASA's Einstein Program at the Space Telescope Science Institute (STScI) in Baltimore, Maryland. "We are trying to identify whether distant supernovae are fundamentally different or very similar to what we see in the nearby universe."
Peyerle and other STScI researchers provided an analysis to determine which transients are really supernovae and which are not, since they often look very similar.
The team detected several high-redshift supernovae, including the most distant supernova ever confirmed spectroscopically, at a redshift of 3.6. Its parent star exploded when the universe was only 1.8 billion years old. This is a supernova called a core collapse, the explosion of a massive star.
