Deep-space flashes light up a new face of Nature

CSIRO’s Parkes radio telescope has detected brief flashes of radio emission from the distant Universe. Their origin is unknown.

CSIRO’s Parkes radio telescope in eastern Australia has detected mysterious ‘flashes’ of radio energy from the distant Universe that may open up a whole new area of astrophysics. The surprising finding, made by a team of scientists from ten institutions in Australia, the USA, UK, Germany and Italy, is published in today’s issue of the journal Science.

“A single burst of radio emission of unknown origin was detected outside our galaxy about six years ago but no one was certain what it was or even if it was real.”

Dan Thornton, PhD student with the University of Manchester and CSIRO.

“Staggeringly, we estimate there could be one of these flashes going off every ten seconds somewhere in the sky,” said research team member Dr Simon Johnston, Head of Astrophysics at CSIRO Astronomy and Space Science.

Four flashes were detected, each from a different direction and each lasting for only a millisecond (a thousandth of a second).

The characteristics of the radio signal — how it is ‘smeared out’ in frequency from travelling through space — indicate that the flashes came from up to 11 billion light-years away.

No gamma rays or X-rays were detected in association with the flashes, and the astronomers have ruled out the flashes being from phenomena such as gamma-ray bursts, the merger of two neutron stars, merging black holes, or evaporating black holes.

Dan Thornton, a PhD student with the University of Manchester and CSIRO, is the lead author on the Science paper. “A single burst of radio emission of unknown origin was detected outside our galaxy about six years ago but no one was certain what it was or even if it was real,” he said. “So we have spent the last four years searching for more of these explosive, short-duration radio bursts.”

That original radio flash, known as the ‘Lorimer burst’ after its discoverer, was also found with CSIRO’s Parkes telescope.

“Finding these things requires both a sensitive telescope and spending enough time looking, and that’s what we’ve done with Parkes,” said Dr Johnston.

CSIRO’s Australian SKA Pathfinder telescope, now under construction in Western Australia, will be running a major survey for transient radio sources like the ones just found with Parkes.

“With the ability to detect these very fast sources we are opening up a whole new area of astrophysics,” said Dr Johnston.

Contact: Sheryl Weinstein
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New Jersey Institute of Technology
Using the sun to illuminate a basic mystery of matter

Antimatter has been detected in solar flares via microwave and magnetic-field data, according to a presentation by NJIT Research Professor of Physics Gregory D. Fleishman and two co-researchers at the 44th meeting of the American Astronomical Society’s Solar Physics Division. This research sheds light on the puzzling strong asymmetry between matter and antimatter by gathering data on a very large scale using the Sun as a laboratory.

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.

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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.