Researchers from the United States and Russia analyzing microwave and magnetic-field data from solar-dedicated facilities and spacecraft have reported the first detection of positrons in solar flares.

Associated with solar magnetic storms, solar flares are giant explosions on the Sun that send energy, light and particles into space. Their number increases approximately every 11 years.

Positrons are antimatter counterparts of the electron. Positrons and electrons have the same physical behavior, except that electrons have a negative charge while positrons, as their name implies, have a positive charge. This charge difference causes positrons to emit the opposite sense of circularly polarized radio emission, which Prof Gregory Fleishman from the New Jersey Institute of Technology and his colleagues from the Russia’s Institute of Solar-Terrestrial Physics used to distinguish them.

Using data from NASA’s Solar and Heliospheric Observatory and radio images at two frequencies from Japan’s Nobeyama Radioheliograph, the American-Russian team found that the radio emission from the solar flare was polarized in the normal sense at the lower frequency where the effect of positrons is expected to be small, but reversed to the opposite sense at the same location, although at the higher frequency where positrons can dominate.

The findings were presented July 8 at the 44th meeting of the American Astronomical Society’s Solar Physics Division in Bozeman, Montana.

The study has far-reaching implications for gaining valuable knowledge through remote detection of relativistic antiparticles at the Sun and, potentially, other astrophysical objects by means of radio-telescope observations.

The ability to detect these antiparticles in an astrophysical source promises to enhance our understanding of the basic structure of matter and high-energy processes such as solar flares, which regularly have a widespread and disruptive terrestrial impact, but also offer a natural laboratory to address the most fundamental mysteries of the Universe.

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Bibliographic information: Fleishman GD et al. 2013. Discovery of Relativistic Positrons in Solar Flares with Microwave Imaging and Polarimetry. 44th meeting of the Solar Physics Division of the American Astronomical Society. Paper # 100.79