Thursday, February 18, 2010
The Atacama Cosmology Telescope: Mapping out Structure in the Depths of our Observable Universe
Danica Marsden
Dept. of Physics and Astronomy, University of Pennsylvania
Cosmologists are modern day explorers, building instruments that turn their “eyes”, arrays of photon detectors, on space. By scanning the sky and collecting the photons that arrive at Earth we learn ever more about what exactly is out there, answering the questions: What makes up our Solar System, Milky Way Galaxy, and beyond? With the Cosmic Microwave Background (the afterglow of the Big Bang) as a backlight, the Sunyaev-Zel'dovich Effect (SZE) is the effect of extremely hot intra-galaxy cluster gas giving the CMB photons which happen to pass through them an extra energy kick on their way to us.
The Atacama Cosmology Telescope makes use of the SZE to find these groups of galaxies in sky maps at three radio frequencies. The strength of the SZE is distance independent, allowing us to seek out galaxy clusters as they first formed long ago. Compare this to telescopes such as the Hubble Space Telescope, whose ability to detect very far objects is extremely limited by the objects’ intrinsic brightness. From our maps and catalogs, like Magellan's maps of new lands, we can learn about the lay of the observable Universe. Combining this information with observations by other instruments helps us pin down the exact mixture of "normal" (Baryonic) matter, Dark Matter, Radiation and Dark Energy. I will discuss these concepts and show how we built the Atacama Cosmology Telescope in the Atacama desert of Chile at ~17,000 feet to achieve these ends.
Refreshments at 11:00 AM. Seminar begins at 11:10 AM.
Building 8, Room 241
For further information, please call (909) 869-4014
