Gamma rays produced by solar flares typically have energies ranging from tens of millions of electron volts (MeV) up to several billion electron volts (GeV). Observations from instruments like the Fermi Large Area Telescope (Fermi-LAT) have detected solar flare gamma rays in the energy range of about 30 MeV to 10 GeV. This wide energy range indicates that solar flares can accelerate particles—especially protons and ions—to very high energies, which then produce gamma rays through processes such as pion decay.
Solar flares are intense bursts of radiation caused by the sudden release of magnetic energy stored in the Sun’s atmosphere. When magnetic reconnection occurs, it accelerates charged particles to near-relativistic speeds. These energetic particles collide with the solar atmosphere, producing gamma rays. The gamma rays observed are often modeled by a curved spectrum, such as a power-law with an exponential cutoff or a pion decay spectrum, which reflects the underlying proton and ion acceleration mechanisms rather than just electron emissions.
The detection of gamma rays with energies reaching into the GeV range from solar flares is significant because it reveals that solar flares are capable of accelerating particles to energies much higher than previously thought. For example, the first solar gamma-ray flare was observed in 1991, but more recent observations have expanded the catalog of such events, showing that gamma-ray emission from solar flares is more common and energetic than once believed.
The energy of these gamma rays is important not only for understanding the physics of solar flares themselves but also for studying the Sun’s magnetic environment and particle acceleration processes. High-energy gamma rays can serve as probes into the magnetic fields beneath the solar surface, offering insights into solar activity and space weather phenomena that can affect Earth’s space environment.
In summary, gamma rays produced by solar flares span a broad energy spectrum from about 30 MeV to 10 GeV, reflecting the powerful acceleration of protons and ions during these explosive solar events. This high-energy radiation is a key signature of the extreme physical processes occurring in the Sun’s atmosphere during flares.