When astronomers used the Webb Space Telescope to study the galaxy MRG-M0138 last month, they discovered something unexpected: a supernova in the distant past that has been magnified for your viewing pleasure by the galaxy’s gravitational lens.
A supernova is a bright light source that astronomers can see when stars die because they release a great amount of energy. The second spotted supernova in the lensed region is the one that Webb imaged.
The supernova, known as Encore, was “discovered serendipitously,” according to co-principal investigators of the Webb Director’s Discretionary Time program 6549, Justin Pierel and Andrew Newman, who talked about the finding in a statement from the Space Telescope Science Institute. All of the program’s details are available here.
In a Hubble image from 2016, the first lensed supernova observed in MRG-M0138 was identified. Given that it disappeared and then resurfaced before vanishing in 2019, it was given the name Requiem. Astronomers have estimated that the Requiem supernova would resurface in 2037, give or take a few years, as previously reported by Gizmodo. It appears that the revised timescale is 2035 based on the STScI announcement.
Geographical lenses are areas of space where an object’s gravitational pull bends light farther away, amplifying it for observers on the other side of the object, such as the Webb Space Telescope. These gravitational lenses are used by astronomers to observe extremely faint, far-off, or ancient light; as a result, the lenses make visible some of the furthest light sources that are now visible.
The oldest star, Earendel, was photographed by the Hubble Space Telescope last year. Earendel is part of a tiny gravitationally lensed crescent of stars connected to one another in space like daisy chains. Webb also uses these lenses; during its observation of lensed light from Pandora’s Cluster (Abell 2744) in February, the telescope found hundreds of galaxies that had never been seen before. Webb’s capacity to imaging in infrared and near-infrared light allows it to look farther and discover fainter objects than other observatories, even though other telescopes have already observed the cluster.
It is common for the lenses to generate arcs similar to MRG-M0138. A distinct group of astrophysicists discovered evidence of axionic dark matter earlier this year in Einstein rings, which are exceptional instances in which lensed light forms a whole ring in space, akin to a vast, forbidden cosmic halo.
Since Type 1a supernovae, or “standard candles,” have absolute magnitudes that are known, astronomers can determine the distance between Requiem and Encore. Standard candles are important data points for scientists determining the size of the universe and its expansion pace, which produces varied rates depending on how it’s computed. This is because their distance can be measured. The Hubble Tension, a disparity, still baffles astrophysicists.
Encore and Requiem are the farthest apart standard-candles ever found, according to Pierel and Newman. In just over ten years, Requiem will resurface, giving scientists the chance to recalibrate the Hubble Constant with unprecedented accuracy.
