Lead investigators
Lincoln Greenhill (Harvard Faculty of Arts and Sciences, Harvard-Smithsonian Center for Astrophysics)
Description
The Murchison Wide-field Array is a next-generation radio telescope being built in Australia to study the early universe, the sun, space weather, and time variability of the radio sky. Cosmologists will use the MWA to map matter in the Universe during the Epoch of Reionization soon after the Big Bang, when the earliest stars, galaxies, and quasars formed. That is the MWA’s job by night, when the environment is most radio quiet. The MWA’s job by day will be mapping the Sun, with particular focus on solar storms and the ever-changing solar magnetic field that shapes those storms and in turn determines space weather around Earth. And when not looking at the early universe or the Sun, the MWA will map the radio sky in the first systematic search for variability, as from supernovae, planets, etc. The discovery space is huge.
To a degree unmatched byany other telescope, the MWA is a flexible, reprogrammable “software telescope,” depending entirely on real-time high-performance computing. The array will be a kilometer across. Rather than employ large-diameter reflectors, the MWA will use inexpensive “TV-like” antennas en masse. (There will be thousands.) And rather than track the sky by mechanically steering steel structures as for conventional radio telescopes, the MWA will comprise antennas fixed to the ground and will track the sky using electronics and software to manipulate the signals from each element. Creating camera-like images of the sky will require a supercomputer, on site, in the Australian outback. Absent this innovation, the MWA would be unaffordable.
The challenge of MWA computing is daunting; hundreds of billions of bits per second must be processed on the spot. No comparable system has ever been assembled for astronomy. Development of this real-time system for calibration and imaging is being led by Harvard-Smithsonian researchers in collaboration with the IIC. Construction and testing uses the IIC HPC cluster and in-house knowledge. Investigation of architecture choices and trade-offs in design of the actual MWA on-site cluster is also anticipated. The key to success will be speed, i.e., keeping up with the input data stream. There are conventional solutions. However, MWA and IIC researchers are also working to harness the power of graphics processors (developed to serve gaming). If used appropriately, these processors can run tens or hundreds of times faster than conventional computers that rely on CPUs. Over the long run, use of graphics processors may change paradigms for data processing in astronomy and the (billion-dollar) arrays that may be built on the same site by 2020, for which the MWA is effectively a science and technology pathfinder.
