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Tidal alignments as a contaminant of the galaxy bispectrum

Krause, Elisabeth and Hirata, Christopher M. (2011) Tidal alignments as a contaminant of the galaxy bispectrum. Monthly Notices of the Royal Astronomical Society, 410 (4). pp. 2730-2740. ISSN 0035-8711.

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If the orientations of galaxies are correlated with large-scale structure, then anisotropic selection effects such as preferential selection of face-on disc galaxies can contaminate large-scale structure observables. Here we consider the effect on the galaxy bispectrum, which has attracted interest as a way to break the degeneracy between galaxy bias and the amplitude of matter fluctuations σ_8. We consider two models of intrinsic galaxy alignments: one where the probability distribution for the galaxy’s orientation contains a term linear in the local tidal field, appropriate for elliptical galaxies; and one with a term quadratic in the local tidal field, which may be applicable to disc galaxies. We compute the correction to the redshift space bispectrum in the quasi-linear regime, and then focus on its effects on parameter constraints from the transverse bispectrum, i.e. using triangles (k_1, k_2, k_3) in the plane of the sky. We show that in the linear alignment model, intrinsic alignments result in an error in the galaxy bias parameters, but do not affect the inferred value of σ8. In contrast, the quadratic alignment model results in a systematic error in both the bias parameters and σ8. However, the quadratic alignment effect has a unique configuration dependence that should enable it to be removed in upcoming surveys.

Item Type:Article
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Hirata, Christopher M.0000-0002-2951-4932
Additional Information:© 2010 Royal Astronomical Society. Accepted 2010 September 5. Received 2010 August 31; in original form 2010 April 20. EK and CMH are supported by the U.S. Department of Energy (DE-FG03-92-ER40701) and the National Science Foundation (AST-0807337). CMH is supported by the Alfred P. Sloan Foundation.
Funding AgencyGrant Number
Department of Energy (DOE)DE-FG03-92-ER40701
Alfred P. Sloan FoundationUNSPECIFIED
Subject Keywords:cosmology: theory; large-scale structure of Universe
Issue or Number:4
Record Number:CaltechAUTHORS:20110303-095335768
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:22622
Deposited By: Ruth Sustaita
Deposited On:03 Mar 2011 19:34
Last Modified:03 Oct 2019 02:39

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