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Large-scale velocities and primordial non-Gaussianity

Schmidt, Fabian (2010) Large-scale velocities and primordial non-Gaussianity. Physical Review D, 82 (6). Art. No. 063001 . ISSN 2470-0010.

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We study the peculiar velocities of density peaks in the presence of primordial non-Gaussianity. Rare, high-density peaks in the initial density field can be identified with tracers such as galaxies and clusters in the evolved matter distribution. The distribution of relative velocities of peaks is derived in the large-scale limit using two different approaches based on a local biasing scheme. Both approaches agree, and show that halos still stream with the dark matter locally as well as statistically, i.e. they do not acquire a velocity bias. Nonetheless, even a moderate degree of (not necessarily local) non-Gaussianity induces a significant skewness (~0.1–0.2) in the relative velocity distribution, making it a potentially interesting probe of non-Gaussianity on intermediate to large scales. We also study two-point correlations in redshift space. The well-known Kaiser formula is still a good approximation on large scales, if the Gaussian halo bias is replaced with its (scale-dependent) non-Gaussian generalization. However, there are additional terms not encompassed by this simple formula which become relevant on smaller scales (k ≳ 0.01h/Mpc). Depending on the allowed level of non-Gaussianity, these could be of relevance for future large spectroscopic surveys.

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Additional Information:© 2010 The American Physical Society. Received 1 June 2010; published 1 September 2010. I am grateful to V. Desjacques for very helpful discussions and providing important insights in the initial stages of this project. Thanks also goes to U. Seljak and the Institute for Theoretical Physics at the University of Zürich for their hospitality. Further, I would like to thank M. Kamionkowski, N. Afshordi, T. Baldauf, N. Dalal, U. Seljak, R. Scoccimarro, and especially O. Doré for enlightening discussions. This work was supported by the Gordon and Betty Moore Foundation at Caltech.
Group:Moore Center for Theoretical Cosmology and Physics
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Issue or Number:6
Classification Code:PACS: 95.30.Sf, 95.36.+x, 98.80.-k, 98.80.Jk
Record Number:CaltechAUTHORS:20100920-090928112
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:20032
Deposited By: Tony Diaz
Deposited On:20 Sep 2010 16:44
Last Modified:03 Oct 2019 02:04

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