Is there scale-dependent bias in single-field inflation?
- Creators
- de Putter, Roland
- Doré, Olivier
- Green, Daniel
Abstract
Scale-dependent halo bias due to local primordial non-Gaussianity provides a strong test of single-field inflation. While it is universally understood that single-field inflation predicts negligible scale-dependent bias compared to current observational uncertainties, there is still disagreement on the exact level of scale-dependent bias at a level that could strongly impact inferences made from future surveys. In this paper, we clarify this confusion and derive in various ways that there is exactly zero scale-dependent bias in single-field inflation. Much of the current confusion follows from the fact that single-field inflation does predict a mode coupling of matter perturbations at the level of f_(NL)^(local); ≈ −5/3, which naively would lead to scale-dependent bias. However, we show explicitly that this mode coupling cancels out when perturbations are evaluated at a fixed physical scale rather than fixed coordinate scale. Furthermore, we show how the absence of scale-dependent bias can be derived easily in any gauge. This result can then be incorporated into a complete description of the observed galaxy clustering, including the previously studied general relativistic terms, which are important at the same level as scale-dependent bias of order f_(NL)^(local) ~ 1. This description will allow us to draw unbiased conclusions about inflation from future galaxy clustering data.
Additional Information
© 2015 IOP Publishing Ltd and Sissa Medialab srl. Received 22 May 2015. Accepted 28 August 2015. Published 12 October 2015. We thank the participants of the workshop Testing Inflation with Large Scale Structure: Connecting Hopes with Reality held at CITA, University of Toronto in October 2015 for stimulating discussions. We particularly thank Matias Zaldarriaga for several insights and for highlighting the relevance of proper physical scales in this problem. Part of the research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. This work is supported by NASA ATP grant 11-ATP-090. D.G. is supported by a NSERC Discovery Grant.Attached Files
Submitted - 1504.05935v1.pdf
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Additional details
- Eprint ID
- 63315
- Resolver ID
- CaltechAUTHORS:20160104-085306816
- NASA/JPL/Caltech
- 11-ATP-090
- NASA
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- Created
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2016-01-04Created from EPrint's datestamp field
- Updated
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2023-03-15Created from EPrint's last_modified field