by When it comes to hunting the explosive deaths of massive stars in the early universe, the James Webb Space Telescope (JWST) is quite the cosmic detective. This celestial Sherlock Holmes has found evidence of 80 new supernovae in a patch of sky as wide as a grain of rice held at arm’s length.
Not only is this 10 times more supernovae than previously found in cosmic history so early, but the sample also includes the earliest and longest supernova ever seen. It is one that exploded when the universe was 13.8 billion years old but 1.8 billion years old.
Data from the JWST Advanced Deep Extragalactic Survey (JADES) program helped a team of scientists discover this unprecedented supernova flag, including more Type Ia explosions that astronomers call “standard candles” and can use to measure cosmic distances to measure.
Before JWST began operating in the summer of 2022, only a handful of supernovae had been discovered dating back to when the universe was only 3.3 billion years old, equal to about 25% of its current age. In the JADES sample, however, there are many supernovae that exploded further back in the past. In fact, some erupted when the universe was less than 2 billion years old.
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“The JWST is a supernova discovery machine,” team member Christa DeCoursey, a third-year graduate student at the Steward Observatory and the University of Arizona in Tucson, said in a statement. “The large number of detections and the great distance to these supernovae are the two most exciting results from our survey.”
The JWST’s unrivaled infrared sensitivity means that it is discovering supernovae almost everywhere it looks in the cosmos.
The supernova detective
When wavelengths of light travel through the cosmos, the expansion of the fabric of space stretches those wavelengths out. This is because light moves further down the electromagnetic spectrum in terms of classification, going from the blue end to the redder end. This phenomenon is called “redshift”.
The longer the light travels through space, the more extreme it is redshifted. Thus, there has been a large increase in wavelength, or a “cosmological reshift” of light from bodies located about 12 billion light-years away, such as these supernotes.
This supernova light moves down into the infrared region of the electromagnetic spectrum, a region where the JWST is capable of viewing the universe.
The Hubble Space Telescope had previously allowed astronomers to observe supernovae as far back as when the universe was a “young adult”. With JADES and the JWST, however, astronomers can observe supernovae when the cosmos is in its “teens” or even in its “teens”.
In the future, scientists hope to look back at the stage of the universe of the “baby” – or even back to its cosmic beginning, ideally collapsing on the death of the first generation of giant stars.
To obtain this new cavalcade of supernova observations, the JADES team took multiple images of the same patch of sky at one-year intervals. Then, they compared the images. Because supernovae are “transient”, meaning they brighten and fade over time, the changes in the images allowed scientists to distinguish which points of light were exploding stars and which phenomena probably another.
“This is really our first example of what a high-redshift universe looks like for transient science,” JADES team member Justin Pierel, a NASA Einstein Fellow at the Space Telescope Science Institute (STScI) in Baltimore, Maryland, said in the statement. . “We are trying to identify whether distant supernovae are fundamentally different or very similar to what we see in the nearby Universe.”
The supernovae observed by the JADES team were not “core” supernovae, triggered when massive stars run out of the fuel supply needed for nuclear fusion in their cores and collapse under their own gravity, capturing a black hole or neutron star.
As mentioned, some Type Ia supernovae have been triggered when interstellar bodies known as “white dwarfs” cannibalistically feed on material removed from a companion, or donor, star. This material accumulates on the surface of the white dwarf until it triggers a runaway thermonuclear explosion that completely destroys the white dwarf.
The light outputs of these events are uniform with the same intrinsic brightness, apparently regardless of distance. This means they can be used as cosmic rulers to measure distance and also act as markers to measure the rate at which the fabric of space is expanding. However, if the intrinsic brightness of Type Ia supernovae changed at high redshifts, their utility in measuring large cosmic distances would be limited.
The team’s observations of Type Ia, which erupted about 11 billion years ago, revealed that its brightness had not changed despite a cosmological change in its light.
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The “pre-teen” universe was a very different place than we see today, with much more extreme environments. Furthermore, because the universe at this time was mostly hydrogen and helium, astronomers expect ancient astronomers to see constellations fueled by the death of stars with far fewer heavy chemical elements, or “metals” in them are the current generation of “metal-rich” stars. like the sun.
Therefore, comparing these ancient stars as they were formed by metals created by the constellations and scattered through the cosmos as they die could help scientists better understand these ancient stars. these ancient supernovae and massive stars exploding in the local universe.
“We are essentially opening a new window on the transient universe,” said Matthew Siebert, head of the spectroscopic analysis of the JADES supernova. “Historically, whenever we’ve done that, we’ve found very exciting things – things we didn’t expect.”
The team’s findings were presented at a press conference at the 244th meeting of the American Astronomical Society in Madison, Wisconsin, on Monday (June 10).
