Using the sun to illuminate a basic mystery of matter

While antiparticles can be created and then detected with costly and complex particle-accelerator experiments, such particles are otherwise very difficult to study. However, Fleishman and the two co-researchers have reported the first remote detection of relativistic antiparticles — positrons — produced in nuclear interactions of accelerated ions in solar flares through the analysis of readily available microwave and magnetic-field data obtained from solar-dedicated facilities and spacecraft. That such particles are created in solar flares is not a surprise, but this is the first time their immediate effects have been detected.

The results of this research have 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 we live in.

Electrons and their antiparticles, positrons, 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 Fleishman and his colleagues used to distinguish them. To do that required knowledge of the magnetic field direction in the solar flare, provided by NASA's Solar and Heliospheric Observatory (SOHO), and radio images at two frequencies from Japan's Nobeyama Radioheliograph. Fleishman and his colleagues found that the radio emission from the flare was polarized in the normal sense (due to more numerous electrons) at the lower frequency (lower energy) 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 (higher energy) where positrons can dominate.

Fleishman, who is affiliated with the NJIT Center for Solar-Terrestrial Research, worked with Alexander T. Altyntsev and Natalia S. Meshalkina, Institute of Solar-Terrestrial Physics, Siberian Branch of the Russian Academy of Sciences. They are presenting their research in a paper titled “Discovery of Relativistic Positrons in Solar Flares” at the 44th meeting of the Solar Physics Division of the American Astronomical Society, held in Bozeman, Montana, July 8-11.

NJIT, New Jersey's science and technology university, enrolls approximately 10,000 students pursuing bachelor's, master's and doctoral degrees in 120 programs. The university consists of six colleges: Newark College of Engineering, College of Architecture and Design, College of Science and Liberal Arts, School of Management, College of Computing Sciences and Albert Dorman Honors College. U.S. News & World Report's 2012 Annual Guide to America's Best Colleges ranked NJIT in the top tier of national research universities. NJIT is internationally recognized for being at the edge in knowledge in architecture, applied mathematics, wireless communications and networking, solar physics, advanced engineered particulate materials, nanotechnology, neural engineering and e-learning. Many courses and certificate programs, as well as graduate degrees, are available online through the Division of Continuing Professional Education.