NASA Fermi Space Telescope Discovers Odd Supernova 'SN 2023ixf' With No Gamma Rays

As they used NASA's Fermi space telescope to examine a nearby supernova, scientists ended up uncovering a more peculiar mystery.

SN 2023ixf: Supernova With No Gamma Rays

The scientists found that the SN 2023ixf supernova completely lacked gamma rays that are typically present when cosmic ray particles accelerate to speeds that are near light. Such a discovery could end up challenging supernova understanding since scientists have believed for a long time that supernovae are factories of cosmic rays that pump out gamma rays in incredible quantities.

The supernova is a recent discovery found on May 18, 2023. It is located close to the Messier 101 (M101) galaxy called the pinwheel galaxy, situated roughly 21 million light-years away from the planet. It is caused by the collapse and death of a supergiant star that had a mass that was thought to be roughly 12 times the Sun's.

SN 2023ixf is considered the brightest supernova relatively close to the planet, which the space telescope has spotted since the beginning of its similar operations in 2008.

The absence of the key ingredient makes the supernova incredibly odd. Guillem Marti-Devesa, a researcher from the University of Trieste and a team member, explains that previously, astrophysicists estimated that supernovas transform roughly 10% of their full energy into cosmic ray acceleration. However, such a process was never observed directly.

With the supernova's new observations, the calculations show that the energy conversion is as low as 1% within a few days post-explosion. The researcher notes that this does not discredit the fact that supernovas are factories for cosmic rays. Rather, it means that much remains to be uncovered regarding their production.

Factories For Cosmic Rays

Each day, trillions of cosmic rays crash into Earth's atmosphere. Roughly 90% of the charged particles are hydrogen's atomic nuclei, while the remains are heavier-element nuclei or free electrons.

However, the cosmic ray source has been hard to investigate. This is because as the particles move through millions of light years to arrive on Earth, they meet various magnetic fields that divert them. Due to endless bouncing, the cosmic rays' trajectory is almost impossible to reconstruct. Protons or gamma rays of higher energy do not undergo such deflections. Hence, they could be used as cosmic ray production tracers.

Elizabeth Hays, the project scientist of the Fermi space telescope at NASA's Goddard Space Flight Center, explains that gamma rays travel directly to the Earth. When cosmic rays interact with environmental matter, they produce gamma rays.

Since Fermi is a gamma-ray telescope with the highest sensitivity in orbit, scientists should shed light on the absence of it if it does not detect an expected signal. Shedding light on such a mystery could help construct a more comprehensive and accurate picture of the origins of cosmic rays.

Scientists think there are some possible explanations for why the supernova produces cosmic rays but not gamma rays that Fermi can detect. One hypothesis claims that the debris of the supernova is distributed unevenly and aligns so that gamma rays do not stream toward the planet. Another explanation is that the debris surrounding the supernova could absorb the produced gamma rays.

Moving forward, astronomers will further examine the supernova in other light wavelengths and construct computer models to learn more about the mechanisms behind its peculiar appearance.

The team's research has been accepted for publication in the Astronomy and Astrophysics journal.

Check out more news and information on Space in Science Times.