TY - JOUR

T1 - 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

AU - Vallinotto, Alberto

AU - Viel, Matteo

AU - Das, Sudeep

AU - Spergel, David N.

PY - 2011/7/1

Y1 - 2011/7/1

N2 - 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.

AB - 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.

KW - cosmic background radiation

KW - gravitational lensing: weak

KW - intergalactic medium

KW - large-scale structure of universe

KW - neutrinos

UR - http://www.scopus.com/inward/record.url?scp=79959951068&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=79959951068&partnerID=8YFLogxK

U2 - 10.1088/0004-637X/735/1/38

DO - 10.1088/0004-637X/735/1/38

M3 - Article

AN - SCOPUS:79959951068

SN - 0004-637X

VL - 735

JO - Astrophysical Journal

JF - Astrophysical Journal

IS - 1

M1 - 38

ER -