NASA’s “Fermi” telescope has made an intriguing discovery of an unusual supernova star, SN 2023IXF, which notably lacks gamma rays. Gamma rays are crucial in the acceleration of cosmic rays to near light speeds, challenging the traditional understanding of supernova mechanisms as factories of cosmic rays. The supernova SN 2023IXF was first detected on May 18, 2023, in the Galaxy Messier 101, also known as the “Galaxy Twal,” situated 21 million light years away from Earth.
Typically, it is believed that supernovae convert about 10% of their energy into cosmic ray acceleration, but observations of SN 2023IXF indicated that this conversion rate may only be at 1% in the initial days post-explosion. While this does not rule out the possibility of cosmic ray formation during a supernova event, it suggests the necessity for further investigation.
One key aspect that sets this supernova apart is the absence of gamma rays, which serve as direct evidence of cosmic ray production. In 2013, the Fermi telescope uncovered similar phenomena in supernova remnants within our own galaxy. However, data from SN 2023IXF contradicts these findings, as gamma rays have not been observed even several months after the supernova was first spotted in visible light.
Possible explanations for this anomaly include the uneven distribution of supernova fragments or the absorption of gamma rays by surrounding material. The research team intends to continue studying SN 2023IXF across different wavelengths and develop computational models to pinpoint the causes behind the supernova’s unconventional behavior.
The study, which has been accepted for publication in the journal Astronomy and Astrophysics, underscores that the absence of gamma rays does not necessarily equate to a lack of cosmic rays. This discovery paves the way for new insights into acceleration mechanisms and environmental factors that influence cosmic ray production.