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Probing Dark Matter, Distant Galaxies

Megan Donahue, professor, Department of Physics and Astronomy, has taken a sneak peek at the distant, early universe and its newborn galaxies, and at the same time she and her colleagues are learning about the dark matter inside clusters of galaxies.

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Megan Donahue

Donahue and her team are collaborating with CLASH (Cluster Lensing And Supernova survey with Hubble) – an international group of scientists who are conducting “an innovative survey to place new constraints on the fundamental components of the cosmos using the Hubble Space Telescope.” They have been been awarded the equivalent of one month of observing time with the Hubble Space Telescope (HST), almost 800 hours of telescope time, spread over three years, to study 25 of the most massive clusters of galaxies in the universe.

The research team takes advantage of the fact that the Hubble Space Telescope takes multiple images of a cluster that originate from the same background source. The locations and distortions of the images indicate how the “lens” is bending or distorting the light that passes through. So these lensed versions of background galaxies reveal not only how much dark matter exists there, but also where dark matter is located within the cluster of galaxies.

The goal is to measure this effect with as many multiple-lensed background systems as possible. Since the scientists wish to measure exactly where dark matter is residing at a resolution similar to the resolution of NASA’s Hubble Space Telescope, over a large field, manipulations of millions of pixels are required in each computational step.

For this massive calculation, they use both the Institute for Theoretical Astrophyiscs at Heidelberg University and the MSU High Performance Computing Center machinery to perform many parallel calculations. In particular, multiple cores and GPU (a graphics processing unit, rather than simple CPU) capabilities enabled them to speed up these massive calculations. This computational power has helped them analyze about 20 gravitational lenses, uncovering many multiple images of different sources, and producing high-end scientific results and dark matter maps. In fact, few of the farthest galaxies known to date have been found behind the clusters we analyzed, allowing a deep magnified view into the early universe.

Photo: The Hubble Space Telescope as seen from the departing Space Shuttle Atlantis, flying STS-125, HST Servicing Mission 4, May 19, 2009; Source http://spaceflight.nasa.gov/gallery/images/shuttle/sts-119/hires/s125e011848.jpg
Author: Ruffnax (Crew of STS-125)

Related Story – Megan Donahue: Galaxy Quest

– Institute for Cyber-Enabled Research (iCER)

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