The maximum energy of gamma rays emitted from solar flares typically reaches into the range of several giga-electron volts (GeV), with observations detecting gamma rays up to about 10 GeV. Solar flares are powerful explosions on the Sun that release enormous amounts of energy across the electromagnetic spectrum, including high-energy gamma radiation. The Fermi Large Area Telescope (LAT) has cataloged solar flares emitting gamma rays in the energy range from roughly 30 MeV (million electron volts) up to around 10 GeV during Solar Cycle 24, which is a significant extension beyond earlier detections[4].
These high-energy gamma rays arise primarily due to interactions involving accelerated protons and heavier ions within the flare environment. When these energetic particles collide with nuclei in the solar atmosphere, they produce nuclear reactions that emit gamma photons at very high energies. This process differs from lower-energy emissions dominated by electrons and X-rays; instead, it reflects proton and ion acceleration mechanisms occurring during magnetic reconnection events in solar flares.
Historically, nuclear gamma-ray lines were observed as early as the 1970s during major solar flare events, confirming that such energetic processes occur on our Sun[1]. More recent space-based observatories like Fermi-LAT have greatly improved sensitivity and have detected numerous flares producing sustained emission at GeV energies.
While typical maximum energies for solar flare-related gamma rays reach around 10 GeV, it is important to distinguish these from other cosmic sources of even higher energy gamma rays—such as those detected by ground-based observatories or specialized instruments like LHAASO—which can observe photons with energies up to quadrillions of electron volts (PeVs). These ultra-high-energy cosmic gamma rays come from distant astrophysical phenomena rather than our Sun[2].
Solar flare plasma temperatures can soar tens of millions Kelvin due to intense magnetic reconnection heating processes. This extreme environment accelerates particles efficiently enough to generate these very energetic photons[3]. The detection and study of such high-energy emissions provide crucial insights into particle acceleration physics near our star and help improve understanding not only of space weather impacts but also fundamental plasma processes.
In summary: Gamma-ray emissions measured directly from solar flares reach maximum photon energies on the order of about **10 giga-electron volts**, produced mainly through proton-induced nuclear interactions during intense magnetic activity on the Sun’s surface. These measurements represent some of the highest photon energies associated specifically with our star’s explosive events known so far.