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Physical Society Colloquium
David Helfand Columbia University We began collecting Faint Images of the Radio Sky at Twenty-cm with the Very Large Array radio interferometer in April of 1993. The goal is to construct the centimetric equivalent of the Palomar Observatory Sky Survey (POSS -- the standard archive of the optical sky) over the 10,000 square degrees of the northern sky that will be covered by the Sloan Digital Sky Survey. The 23,000 two-million pixel images we have produced to date cover 8000 square degrees and contain 720,000 radio sources with subarcsecond positions. Both the sensitivity and resolution of the survey are fifty times better than heretofore available. Approximately 20% of these sources have optical counterparts on the POSS I plates; identified objects range from stars within 10 ly to quasars at z4. Following a brief precis of the survey's design and implementation, I will discuss our use of the survey to define the large-scale structure of the Universe on scales not yet explored. In particular, we have calculated the first angular correlation function for radio sources, have demonstrated the value of bent-double radio sources as tracers of the high-density Universe at high redshift, have found an efficient method of discovering gravitational lenses, and we are constraining the total (dark plus luminous) matter distribution through its weak gravitational lensing effect on the background radio sources.
Friday, October 5th 2001, 15:30 |