Fast Fourier transform telescope

Max Tegmark and Matias Zaldarriaga
Phys. Rev. D 79, 083530 – Published 28 April 2009


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 large-area surveys. The key advantages over traditional interferometers are cost (the correlator computational cost for an N-element array scales as Nlog2N rather than N2) 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.

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  • Received 2 June 2008


©2009 American Physical Society

Authors & Affiliations

Max Tegmark

  • Department of Physics & MIT Kavli Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA

Matias Zaldarriaga

  • Center for Astrophysics, Harvard University, Cambridge, Massachusetts 02138, USA

See Also

Omniscopes: Large area telescope arrays with only NlogN computational cost

Max Tegmark and Matias Zaldarriaga
Phys. Rev. D 82, 103501 (2010)

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Vol. 79, Iss. 8 — 15 April 2009

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