Primordial Non-Gaussianity in the Forest: 3D Bispectrum of Lyman-αFlux Spectra along Multiple Lines of Sight

2012/05/31 by Dhiraj Kumar Hazra, Tapomoy Guha Sarkar
Mathematics · Physics and Astronomy · #Anisotropy #Astrophysics #Bispectrum #Cosmic microwave background #Cosmology and Gravitation Theories #Field (mathematics) #Flux (metallurgy) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Lyman-alpha forest #Mathematics #Noise (video) #Non-Gaussianity #Physics #Quantum mechanics #Quasar #Redshift #Spectral density #Statistics #Stellar, planetary, and galactic studies #astro-ph.CO

paper · pdf · doi:10.1103/physrevlett.109.121301

published as Phys. Rev. Lett. 109, 121301 (2012) · 4 pages, 1 figure, 1 table. Accepted for publication in Physical Review Letters

arxiv created 2012/08/19 · openalex publication_date 2012/09/18 · arxiv updated 2012/09/19 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

We investigate the possibility of constraining primordial non-Gaussianity using the 3D bispectrum of the Lyman (Ly)-\ensuremathα forest. The strength of the quadratic non-Gaussian correction to an otherwise Gaussian primordial gravitational field is assumed to be dictated by a single parameter f_NL. We present the first prediction for bounds on f_NL using Ly-\ensuremathα flux spectra along multiple lines of sight. The 3D Ly-\ensuremathα transmitted flux field is modeled as a biased tracer of the underlying matter distribution sampled along 1D skewers corresponding to quasar sight lines. The precision to which f_NL can be constrained depends on the survey volume, pixel noise, and aliasing noise (arising from discrete sampling of the density field). We consider various combinations of these factors to predict bounds on f_NL. We find that in an idealized situation of full sky survey and negligible Poisson noise one may constrain f_NL\ensuremath∼23 in the equilateral limit. Assuming a Ly-\ensuremathα survey covering large parts of the sky (k_min=8\ifmmode×\else\texttimes\fi10^\ensuremath-4 Mpc^\ensuremath-1) and with a quasar density of n=5\ifmmode×\else\texttimes\fi10^\ensuremath-3 Mpc^\ensuremath-2, it is possible to constrain f_NL\ensuremath∼100 for equilateral configurations. The possibility of measuring f_NL at a precision comparable to large scale structure studies maybe useful for joint constraining of inflationary scenarios using different data sets.

Citations

• Primordial non-Gaussianities in the intergalactic medium
• The Power Spectrum of Mass Fluctuations Measured from the Lyα Forest at Redshiftz = 2.5
• Non-Gaussian features of primordial fluctuations in single field inflationary models
• Non-Gaussianity from Inflation: Theory and Observations
• Probing primordial non-Gaussianity with large-scale structure