Primordial non-Gaussianity, statistics of collapsed objects, and the integrated Sachs-Wolfe effect

Journal Article · Mon Dec 15 04:00:00 EST 2008 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.78.123507· OSTI ID:21251096

Afshordi, Niayesh; Tolley, Andrew J ^[1]

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1. Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario, N2L 2Y5 (Canada)

Any hint of non-Gaussianity in the cosmological initial conditions will provide us with a unique window into the physics of the early Universe. We show that the impact of a small local primordial non-Gaussianity (generated on superhorizon scales) on the statistics of collapsed objects (such as galaxies or clusters) can be approximated by using slightly modified, but Gaussian, initial conditions, which we describe through simple analytic expressions. Given that numerical simulations with Gaussian initial conditions are relatively well studied, this equivalence provides us with a simple tool to predict signatures of primordial non-Gaussianity in the statistics of collapsed objects. In particular, we describe the predictions for non-Gaussian mass function, and also confirm the recent discovery of a nonlocal bias on large scales [N. Dalal, O. Dore, D. Huterer, and A. Shirokov, Phys. Rev. D 77, 123514 (2008).][S. Matarrese and L. Verde, Astrophys. J. 677, L77 (2008).], as a signature of primordial non-Gaussianity. We then study the potential of galaxy surveys to constrain non-Gaussianity using their autocorrelation and cross correlation with the cosmic microwave background (CMB) (due to the integrated Sachs-Wolfe effect), as a function of survey characteristics, and predict that they will eventually yield an accuracy of {delta}f{sub NL}{approx}0.1 and 3, respectively, which will be better than or competitive with (but independent of) the best predicted constraints from the CMB. Interestingly, the cross correlation of the CMB and the NRAO VLA Sky Survey galaxy survey already shows a hint of a large local primordial non-Gaussianity: f{sub NL}=236{+-}127.

• OSTI ID: 21251096
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 12 Vol. 78; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
CORRELATIONS
COSMOLOGICAL MODELS
FORECASTING
GALAXIES
GRAVITATIONAL COLLAPSE
MASS
POTENTIALS
RELICT RADIATION
SIMULATION
STATISTICS
UNIVERSE