NASA Explains Fermi Telescope Does Not Detect Gamma-Rays From Nearby Supernova
NASA’s Fermi Gamma-ray Space Telescope "detected none of the high-energy gamma-ray light" from a nearby supernova. NASA explains.
Credit: NASA Goddard Space Flight Center
Credit: NASA Goddard Space Flight Center
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TechTranscript
00:00NASA's Fermi Gamma-ray Space Telescope
00:04watches the sky for gamma rays, the highest energy form of light.
00:08These detections help scientists learn more about the most powerful
00:12events in the cosmos. However, a recent absence
00:16of gamma ray detection may have been just as informative.
00:20Cosmic rays are small particles like protons and helium nuclei
00:24traveling at nearly the speed of light. It takes a lot of energy to
00:28accelerate them to that speed, so scientists assume they're driven by
00:32powerful events like exploding stars, called supernovae.
00:36Because cosmic rays are charged particles, they interact with magnetic
00:40fields as they travel. These interactions mean they don't follow a
00:44straight line from their sources, and so scientists can't trace where they came from.
00:48But when cosmic rays smash into other particles, they produce gamma rays.
00:52And gamma rays do travel to us straight from their
00:56sources. Fermi has even detected such gamma rays from
01:00supernova remnants, which are thousands of years old.
01:04If supernovae and their remnants really are a key source of cosmic rays,
01:08then calculations tell astronomers how many gamma rays Fermi should detect.
01:12But so far, the telescope hasn't seen enough gamma
01:16rays from these sources. Scientists had suspected
01:20this was because the supernovae were too far away, or observations began
01:24too late, well after peak production.
01:28In May 2023, Fermi observed the most luminous nearby
01:32supernova seen since the mission launched 15 years ago.
01:36It captured data from the first few weeks of the explosion, when scientists
01:40anticipated the greatest production of cosmic rays. But Fermi
01:44didn't see any gamma rays from the explosion.
01:48Scientists aren't yet sure what this means for the link between cosmic rays and supernovae.
01:52There's still a lot of work left to do, but Fermi's non-detection
01:56has added a very important new piece to this high-energy
02:00puzzle.