A Tale of Stellar Explosions: Unraveling the Mysteries of the Universe through Gravitationally Lensed and Nearby Supernova

Scientists have recently revealed a significant discovery that is being referred to as the tip of the iceberg for gravitationally lensed supernovas. This discovery may provide crucial insights for understanding the expansion of the universe. The gravitationally warped and magnified light from a supernova, known as SN Zwicky, has revealed an exceptionally rare occurrence that sheds light on stellar explosions and potentially unseen galaxies. The light from this supernova, which is situated over four billion light-years away, was lensed and magnified up to 25 times by the gravity of a distant galaxy. This galaxy, albeit faint and not notably large from our perspective, effectively acted as a cosmic magnifying glass due to its mass, consisting of stars, gas, and an invisible halo of dark matter. The warped space around this galaxy caused the light from SN Zwicky to follow four different paths, resulting in the supernova being split into four images. This remarkable phenomenon, known as gravitational lensing, is a direct outcome of Albert Einstein’s general theory of relativity. Despite being a rarity, it has been a subject of long-standing scientific discussion and interest. The gravity from the lensing galaxy distorted and brightened the light from SN Zwicky, creating a unique spectacle of multiple images of the exploding star in the sky.

The Discovery of SN Zwicky

The SN Zwicky was first spotted on Aug. 21, 2022, by Caltech’s Zwicky Transient Facility (ZTF) at Palomar Observatory. Officially cataloged as SN 2022qmx, this supernova was the result of the destruction of a white dwarf star, classified as a type Ia supernova. The subsequent study of this cosmic event was led by Ariel Goobar of Stockholm University in Sweden, with follow-up observations conducted by various renowned observatories, including the W. M. Keck Observatory, the Hubble Space Telescope, and the Very Large Telescope, among others. Intriguingly, the four images of the supernova, warped by the gravitational lens, varied in brightness. Researchers have suggested that this variation could be due to smaller ‘microlensing’ events within the lensing galaxy, offering clues about the distribution of star masses in the galaxy’s core. Astronomers believe that the central region of galaxies fosters the formation of a larger number of massive stars than usual, which are the most likely candidates for the microlenses.

Supernovas: A Key to Unlocking Cosmic Mysteries

Observing such lensed supernovas provides critical data in efforts to map the expansion of the universe. This is because type Ia supernovas explode with a standard brightness, and by comparing their intrinsic luminosity with their apparent brightness in our telescopes, astronomers can estimate their distance and subsequently infer the rate of cosmic expansion. In addition, gravitational lenses extend our cosmic ‘distance ladder’ by enabling the detection of supernovas from farther away, thereby allowing scientists to test the strength of dark energy — the mysterious force propelling the acceleration of the universe’s expansion — at different epochs in the universe’s history.

Observing a Nearby Supernova: The Story of SN 2023ixf

While the study of distant, lensed supernovas like SN Zwicky continues, astronomers are also keeping a keen eye on stellar explosions closer to home. A supernova named SN 2023ixf was recently observed in the Pinwheel Galaxy, approximately 21 million light-years away from Earth. The cosmic event was witnessed through the Gemini North telescope atop Mauna Kea in Hawaii by Japanese astronomer Koichi Itagaki on May 19. This supernova, which represents a star collapsing on itself, was the closest one observed in five years. In the photo shared by the astronomer, the supernova can be seen shining brightly in a bluish point of light on the far left of one of the spiral arms of the Pinwheel Galaxy, also known as Messier 101 or M101.

Insights from the Supernova SN 2023ixf

SN 2023ixf is classified as a Type II supernova, a common occurrence in the arms of spiral galaxies. Such stellar explosions happen when stars eight to 50 times more massive than our sun run out of fuel, collapse inward, and finally explode in incredible bursts of energy. The National Science Foundation’s NOIRLab stated that a Type II supernova could release as much energy as our sun will throughout its entire life within just 10 seconds. According to NOIRLab, observations of the supernova over the coming months will allow astronomers to study how the light from the supernova fades and how its spectrum evolves over time. These insights will help astronomers better understand the physics of such explosions. These recent discoveries, from the warped and lensed supernova SN Zwicky to the nearby SN 2023ixf, are just examples of how astrophysicists utilize these stellar explosions to explore some of the biggest questions of the universe. From understanding the expansion of the universe to unraveling the nature of dark matter and dark energy, supernovas continue to be a key tool in our quest to understand the cosmos. For more details on the topic, visit NASA’s official page on the Pinwheel Galaxy.