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Colloquium: Measuring the Large Scale Structure and Dynamics of the Universe with the Atacama Cosmology Telescope

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Suzanne Staggs, Princeton University
When
30 January 2014 from 4:00 PM to 5:00 PM
Where
117 Osmond Laboratory
Contact Name
Contact Phone
814-863-9595
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The cosmic microwave background (CMB) probes the large scale structure and dynamics of the universe in a myriad of ways.  
The Atacama Cosmology Telescope (ACT) is a 6 m telescope specifically designed to measure the CMB  at millimeter wavelengths.  ACT has an angular resolution of better than 1.4', which means it measures not only the primordial fluctuations in the CMB (tracing the seeds of large scale structure), but is also sensitive to the intervening universe in several ways.  ACT observes from a site at 5300 m in the Atacama Desert in Chile.  This midlatitude site allows ACT to map regions of the sky in which there exist substantial data from surveys at other wavelengths.   ACT detects clusters of galaxies through their Sunyaev-Zeldovich effect (a spectral effect due to scattering off the hot electrons in the clusters).  ACT measures clusters directly, in blind surveys, and also makes statistical measurements based on stacking analyses and by measuring the 3-point function in the maps.  Furthermore, gravitational lensing by all the intervening matter from the primordial epoch to now leads to signatures in the 4-point functions in the ACT maps.  Cross-correlating the ACT lensing deflection field with other optical surveys in the same region is a particularly fruitful way of deriving cosmological information on the dynamics of the universe, namely its expansion history.
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