In the eyes of the James Webb Space Telescope, astronomers saw something rare. Pictures of a supernova at different stages of its evolution. A unique opportunity for them to measure the speed at which the universe is expanding. It is enough to confirm that something is wrong with our cosmological model.
The story begins with a question. “So what are these three points that did not exist before?” Before that, it was in 2015. When the Hubble Space Telescope looked toward a cluster of galaxies in the Ursa Major constellation called PLCK G165.7+67.0 (G165, for short). The three dots are bright objects detected in an image of the same area recently returned by the James Webb Space Telescope.
The answer is, AstronomersAstronomers Found it. These three points correspond to a supernova. Three points for one supernova? definitely. Because between us and the supernova, there is a group of galaxies. Under the influence of gravitational lensing, its mass is bent to… a lighta light For the supernova to provide us with three images at three different moments of its explosion. Researchers say a little, as if three MirrorsMirrors To the first he gave an image of a person raising his comb, to the second an image of a person combing his hair, and to the third an image of a person putting down his comb.
Type Ia supernova with gravitational lensing
In a series of articles published in Astrophysical Journalresearchers first tell how they located this supernova in a galaxy located far beyond the cluster G165. In a galaxy that actually existed only 3.5 billion years after the Big Bang. This makes this the only Type Ia supernova ever observed from Earth.
Because this is another piece of information provided by the researchers. This supernova is actually a type Ia supernova. Understand that it is the result of an explosion White dwarfWhite dwarf. Astronomers call this type of supernova a “standard candle.” because brightnessbrightness Type Ia supernovae are known. Measurements of their apparent brightness could therefore make it possible to deduce the distance at which they are located.
Supernova to measure the Hubble constant
All this causes this supernova to be expelled by James Webb Space TelescopeJames Webb Space Telescope Particularly interesting. because SupernovaeSupernovae Gravitational lensing – from the moment astronomers have information about the time lag between images, the supernova distance, and the properties of gravitational lensing – can give an accurate measurement of gravitational lensing. Hubble constantHubble constant. understands, speedspeed thatuniverseuniverse extends. This is why it was called a supernova SNSN H0pe (SN for supernova and H0 for Hubble constant, H0. H0pe for the hope it gives to finally understand this fundamental parameter of our universe).
Because over the past ten years, tension has emerged around this constant. Astronomers talk about it as “Hubble tension”. This arose because two methods for calculating the value of the Hubble constant give different results. By measuring volatility Cosmic microwave backgroundCosmic microwave background – What remains of the first lights that appeared in the universe, after about 380 thousand years Big bangBig bang Only – astronomers found a value of about 67 kilometers per second per megaparsec for H0. It agrees with the predictions of the Standard Model of cosmology. But based on measurementsThe starsThe stars to throb, CepheidsCepheidsthe researchers came up with a value of about 73 kilometers per second per megaparsec. The difference may seem small, but it may be enough to place Standard formStandard form In question.
The tension around the cosmological paradigm has been reactivated
Specifically Calculated value (This work has not yet been reviewed) by researchers for the Hubble constant of a gravitationally lensed supernova of 75.4 kilometers per second per megaparsec. It is thus a value that is more consistent with that provided by measurements made in the local universe. But still to some extent “in tension” With values obtained when our world was small.
Astronomers are already working to obtain more details about SN H0pe. They hope that, thanks to the James Webb Telescope, they will be able to detect other gravitationally lensed supernovae that would allow them to repeat their measurements of H0.
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