Cross-correlations of the Lyα forest with weak-lensing convergence. analytical estimates of signal-to-noise ratio and implications for neutrino mass and dark energy

Alberto Vallinotto, Matteo Viel, Sudeep Das, David N. Spergel

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

We expect a detectable correlation between two seemingly unrelated quantities: the four-point function of the cosmic microwave background (CMB) and the amplitude of flux decrements in quasar (QSO) spectra. The amplitude of CMB convergence in a given direction measures the projected surface density of matter. Measurements of QSO flux decrements trace the small-scale distribution of gas along a given line of sight. While the cross-correlation between these two measurements is small for a single line of sight, upcoming large surveys should enable its detection. This paper presents analytical estimates for the signal-to-noise ratio (S/N) for measurements of the cross-correlation between the flux decrement and the convergence, , and for measurements of the cross-correlation between the variance in flux decrement and the convergence, . For the ongoing BOSS (SDSS-III) and Planck surveys, we estimate an S/N of 30 and 9.6 for these two correlations. For the proposed BigBOSS and ACTPOL surveys, we estimate an S/N of 130 and 50, respectively. Since , the amplitude of these cross-correlations can potentially be used to measure the amplitude of σ8 at z 2%-2.5% with BOSS and Planck and even better with future data sets. These measurements have the potential to test alternative theories for dark energy and to constrain the mass of the neutrino. The large potential signal estimated in our analytical calculations motivates tests with nonlinear hydrodynamic simulations and analyses of upcoming data sets.

Original languageEnglish (US)
Article number38
JournalAstrophysical Journal
Volume735
Issue number1
DOIs
StatePublished - Jul 1 2011

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Keywords

  • cosmic background radiation
  • gravitational lensing: weak
  • intergalactic medium
  • large-scale structure of universe
  • neutrinos

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