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Weak lensing and CMB: Parameter forecasts including a running spectral index

Ishak, Mustapha and Hirata, Christopher M. and McDonald, Patrick and Seljak, Uroš (2004) Weak lensing and CMB: Parameter forecasts including a running spectral index. Physical Review D, 69 (8). Art. No. 083514. ISSN 1550-7998.

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We use statistical inference theory to explore the constraints from future galaxy weak lensing (cosmic shear) surveys combined with the current CMB constraints on cosmological parameters, focusing particularly on the running of the spectral index of the primordial scalar power spectrum, αs. Recent papers have drawn attention to the possibility of measuring αs by combining the CMB with galaxy clustering and/or the Lyman-α forest. Weak lensing combined with the CMB provides an alternative probe of the primordial power spectrum. We run a series of simulations with variable runnings and compare them to semianalytic nonlinear mappings to test their validity for our calculations. We find that a “reference” cosmic shear survey with fsky=0.01 and 6.6 × 10^8 galaxies per steradian can reduce the uncertainty on ns and αs by roughly a factor of 2 relative to the CMB alone. We investigate the effect of shear calibration biases on lensing by including the calibration factor as a parameter, and show that for our reference survey, the precision of cosmological parameter determination is only slightly degraded even if the amplitude calibration is uncertain by as much as 5%. We conclude that in the near future weak lensing surveys can supplement the CMB observations to constrain the primordial power spectrum.

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Hirata, Christopher M.0000-0002-2951-4932
Additional Information:© 2004 The American Physical Society. Received 25 August 2003; published 20 April 2004. M.I. thanks K.F. Huffenberger and R.E. Smith for useful comments on the nonlinear mapping procedures. We thank Alexey Makarov for providing the CMB covariance matrix of current data. We thank Paul Bode for the TPM code. The simulations were performed at the National Center for Supercomputing Applications (NCSA). M.I. acknowledges the support of the Natural Sciences and Engineering Research Council of Canada (NSERC) PDF Program. C.H. acknowledges the support of the National Aeronautics and Space Administration (NASA) Graduate Student Researchers Program (GSRP). U.S. acknowledges support from Packard and Sloan Foundations, NASA NAG5-11983 and NSF CAREER-0132953.
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Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
NASA Graduate Student Research FellowshipUNSPECIFIED
David and Lucille Packard FoundationUNSPECIFIED
Alfred P. Sloan FoundationUNSPECIFIED
Issue or Number:8
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ID Code:11096
Deposited By: Archive Administrator
Deposited On:14 Jul 2008 23:44
Last Modified:03 Oct 2019 00:15

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