Fast Fourier transform telescope
Author(s)Tegmark, Max Erik; Zaldarriaga, Matias
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We propose an all-digital telescope for 21 cm tomography, which combines key advantages of both single dishes and interferometers. The electric field is digitized by antennas on a rectangular grid, after which a series of fast Fourier transforms recovers simultaneous multifrequency images of up to half the sky. Thanks to Moore’s law, the bandwidth up to which this is feasible has now reached about 1 GHz, and will likely continue doubling every couple of years. The main advantages over a single dish telescope are cost and orders of magnitude larger field-of-view, translating into dramatically better sensitivity for largearea surveys. The key advantages over traditional interferometers are cost (the correlator computational cost for an N-element array scales as Nlog[subscript 2]N rather than N[superscript 2]) and a compact synthesized beam. We argue that 21 cm tomography could be an ideal first application of a very large fast Fourier transform telescope, which would provide both massive sensitivity improvements per dollar and mitigate the off-beam point source foreground problem with its clean beam. Another potentially interesting application is cosmic microwave background polarization.
DepartmentKavli Institute for Astrophysics and Space Research; Massachusetts Institute of Technology. Department of Physics
Physical Review D
American Physical Society
Tegmark, Max , and Matias Zaldarriaga. “Fast Fourier transform telescope.” Physical Review D 79.8 (2009): 083530. (C) 2010 The American Physical Society.
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