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Centro de Astrofísica da Universidade do Porto

Estimating the bispectrum of the Very Small Array data

S. Smith, G. Rocha, A. Challinor, R. Battye, P. Carreira, K. Cleary, R. D. Davies, R. J. Davis, C. Dickinson, R. T. Génova-Santos, K. Grainge, C. M. Gutierrez, Y. A. Hafez, M. Hobson, M. E. Jones, R. Kneissl, K. Lancaster, A. Lasenby, P. Leahy, K. Maisinger, G. G. Pooley, N. Rajguru, R. Rebolo López, J. A. Rubiño-Martin, P. S. Molina, R. D. Saunders, R. Savage, P. Scott, A. Slozar, A. C. Taylor, D. Titterington, E. Waldram, R. A. Watson

We estimate the bispectrum of the Very Small Array data from the compact and extended configuration observations released in 2002 December, and compare our results with those obtained from Gaussian simulations. There is a slight excess of large bispectrum values for two individual fields, but this does not appear when the fields are combined. Given our expected level of residual point sources, we do not expect these to be the source of the discrepancy. Using the compact configuration data, we put an upper limit of 5400 on the value of fNL, the non-linear coupling parameter, at 95 per cent confidence. We test our bispectrum estimator using non-Gaussian simulations with a known bispectrum, and recover the input values.

Monthly Notices of the Royal Astronomical Society
Volume 352, Page 887
August 2004

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