Thanks to a curious effect called ” gravitational lensing ” predicted by Albert Einstein a century ago, a team of astronomers from the University of Copenhagen has detected the same supernova on several occasions. And we will see it again in 2037, according to their predictions, which they publish in the journal Nature Astronomy.
Making predictions in the field of astronomy is a challenge as astronomers must rely on data from telescopes, the timing of the next lunar and solar eclipses and the return of some comets. Now this robust prediction features a supernova event from a star named Requiem.
Although it won’t be visible to the naked eye, certain telescopes are expected to be able to pick it up. The three gravitational lensing supernova images, seen as tiny dots captured in a single Hubble snapshot, represent the light from the explosive aftermath. The dots vary in brightness and color, which means that there have been three different phases of the explosion, which fades as it cools over time . That is, in a follow-up image of the cluster taken in 2019, all three points of light had completely disappeared, confirming that they were all mirror images of the same distant light source.
The astronomers discovered that the light came from an ancient supernova located about 10 billion light years from Earth , which means that the star in question lived and died within the first 4 billion years after the Big Bang.
Between us and this distant supernova is a massive galaxy cluster, called MACS J0138.0-2155. Since mass causes space to curve, when starlight (including supernova light) passes through a massive galaxy cluster on its way towards us , the light has to travel in deeply curved space around the cluster. This curvature of starlight creates what astronomers call gravitational lensing. Gravity thus acts like a large celestial zoom lens, magnifying and distorting the light from the supernova and dividing it into multiple copies.
“The Hubble Space Telescope detected three mirror images of the Requiem supernova, scattered in an arc-shaped pattern across the cluster. Each image is a snapshot of the supernova light at different times after the explosive event, ”explain the Hubble scientists.
The observations were made using the infrared wavelength range of the Hubble Space Telescope.
“The fourth image of the galaxy is approximately 21 years late, which should allow us to see the supernova explode once more, around 2037″, explains Gabriel Brammer, co-author of the work.
Astronomers hope that this new observation opportunity will help them gather more information about the cluster and the distribution of the mysterious dark matter within it.
Referencia: Steven A. Rodney, Gabriel B. Brammer, Justin D. R. Pierel, Johan Richard, Sune Toft, Kyle F. O’Connor, Mohammad Akhshik, Katherine E. Whitaker. A gravitationally lensed supernova with an observable two-decade time delay. Nature Astronomy, 2021; DOI: 10.1038/s41550-021-01450-9
