A supernova, or tremendous star explosion, whose light has been so strangely bent by the gravity of another galaxy that it appears as many images in the sky, has been photographed by astronomers. This gravitational lensing phenomena happens when a dense object’s gravity bends and magnifies the light of an object behind it.
The supernova, known as “SN Zwicky,” was first spotted by the Zwicky Transient Facility (ZTF), run by Caltech and headquartered at the Palomar Observatory not far from San Diego. The observation is a part of the largest ongoing supernova survey.
“With ZTF, we have the rare capacity to detect and categorize supernovae very instantly. We quickly realized that we were viewing a very rare phenomenon known as strong gravitational lensing when we noticed that SN Zwicky was brighter than it should have been given its distance from us, says Ariel Goobar, the lead author of the study published today in Nature Astronomy and the director of the Oskar Klein Center at the University of Stockholm in Sweden. Such lensed objects can assist us in conducting a one-of-a-kind investigation into the quantity and distribution of materials at the inner core of galaxies.
Explaining Gravitational Lensing
Light from one cosmic item that hits a dense object on its route to us may experience gravitational lensing, as Albert Einstein predicted more than a century ago. The dense object works as a lens, bending and concentrating light. This warping effect might be weak or strong, depending on the lens’s density and the distance from our eyes. The light from the cosmic object is magnified and split into multiple copies due to severe lensing, which causes the light to be so warped that it is.
Despite the fact that Einstein’s theory of gravitational bending of light was first observed by astronomers in 1919, supernovae’s fleeting nature makes it difficult to detect events like SN Zwicky, also known as SN 2022qmx. In reality, whereas lensed duplicated images of far-off objects known as quasars have been discovered numerous times before, only a small number of supernovae have been lensed into duplicated images. At Palomar, the intermediate Palomar Transient Factory (iPTF), a forerunner to ZTF, found two of these cases: SN Zwicky and ciPTF16geu.
Discovering and Studying SN Zwicky
“SN Zwicky is the smallest resolved gravitational lens system found with optical telescopes. iPTF16geu was a wider system but had larger magnification,” says Goobar.
After SN Zwicky was found by ZTF, Goobar and his worldwide team used a variety of astronomical facilities to monitor and investigate it. The resolution of SN Zwicky by the Near-IR Camera 2 (NIRC2) at the W. M. Keck Observatory on Maunakea in Hawaii showed that the supernova’s lensing was potent enough to have produced numerous photos of the same object.
The ZTF supernova survey, known as the Bright Transient Survey, is conducted by Caltech Optical Observatory staff astronomer Christoffer Fremling. “I was observing that night and was absolutely stunned when I saw the lensed image of SN Zwicky,” he adds. With the Bright Transient Survey, “we catch and classify thousands of transients, giving us a unique ability to find very rare phenomena like SN Zwicky.”
Supernovae, Dark Energy, and Cosmic Mysteries
Supernova SN Zwicky is categorized as a Type Ia object. These are dying stars that give forth a light show that is consistently the same brightness at every event as they end their lives. This special quality helped scientists in 1998 discover that the acceleration of the universe’s expansion was caused by dark energy, a still-unknown entity.
Strongly lensed Type Ia supernovae are magnified, allowing us to look further back in time. We will have a rare opportunity to investigate the nature of dark energy if we can observe more of them, says Joel Johansson, a postdoctoral fellow at Stockholm University and a co-author of the work.
What are the essential elements that are required to model the universe’s expansion history? What constitutes the vast bulk of the mass in galaxies’ dark matter? With the help of ZTF and the planned Vera Rubin Observatory, we will be able to find more ‘SN Zwickys,’ giving us yet another instrument for solving the universe’s riddles.
The ZTF Bright Transient Survey
7,811 verified supernovae have been found so far by the ZTF Bright Transient Survey. The survey’s primary objective is to list and categorize any extragalactic explosion that the instrument can trustably find. ZTF is the largest and most comprehensive survey of its kind at the moment since it quickly scans broad areas of the sky. The brilliant Transient Survey is used by astronomers all across the world to learn about the different types of cosmic explosions that can occur, how frequently they occur, and how brilliant they can get.
Reference: Uncovering a population of gravitational lens galaxies with magnified standard candle SN Zwicky
