Position-dependent power spectrum of the large-scale structure : a novel method to measure the squeezed-limit bispectrum

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalNot applicablepeer-review

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Author(s)

Detail(s)

Original languageEnglish
Journal / PublicationJournal of Cosmology and Astroparticle Physics
Volume2014
Issue number5
Early online date29 May 2014
StatePublished - May 2014
Externally publishedYes

Abstract

The influence of large-scale density fluctuations on structure formation on small scales is described by the three-point correlation function (bispectrum) in the so-called "squeezed configurations," in which one wavenumber, say k3, is much smaller than the other two, i.e.,  k3 << k1 ≈ k2. This bispectrum is generated by non-linear gravitational evolution and possibly also by inflationary physics. In this paper, we use this fact to show that the bispectrum in the squeezed configurations can be measured without employing three-point function estimators. Specifically, we use the "position-dependent power spectrum," i.e., the power spectrum measured in smaller subvolumes of the survey (or simulation box), and correlate it with the mean overdensity of the corresponding subvolume. This correlation directly measures an integral of the bispectrum dominated by the squeezed configurations. Measuring this correlation is only slightly more complex than measuring the power spectrum itself, and sidesteps the considerable complexity of the full bispectrum estimation. We use cosmological N-body simulations of collisionless particles with Gaussian initial conditions to show that the measured correlation between the position-dependent power spectrum and the long-wavelength overdensity agrees with the theoretical expectation. The position-dependent power spectrum thus provides a new, efficient, and promising way to measure the squeezed-limit bispectrum from large-scale structure observations such as galaxy redshift surveys.

Research Area(s)

  • power spectrum, cosmological simulations, PERTURBATION-THEORY, INITIAL CONDITIONS, MATTER, UNIVERSE, SIMULATIONS, EVOLUTION, GALAXIES, DENSITY, HALOES, MODEL

Citation Format(s)

Position-dependent power spectrum of the large-scale structure : a novel method to measure the squeezed-limit bispectrum. / Chiang, Chi-Ting; Wagner, Christian; Schmidt, Fabian; Komatsu, Eiichiro.

In: Journal of Cosmology and Astroparticle Physics, Vol. 2014, No. 5, 05.2014.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalNot applicablepeer-review