TY - JOUR

T1 - Measuring distance ratios with CMB-galaxy lensing cross-correlations

AU - Das, Sudeep

AU - Spergel, David N.

N1 - Copyright:
Copyright 2009 Elsevier B.V., All rights reserved.

PY - 2009/2/6

Y1 - 2009/2/6

N2 - We propose a method for cosmographic measurements by combining gravitational lensing of the cosmic microwave background (CMB) with cosmic shear surveys. We cross-correlate the galaxy counts in the lens plane with two different source planes: the CMB at z∼1100 and galaxies at an intermediate redshift. The ratio of the galaxy count/CMB lensing cross-correlation to the galaxy count/galaxy lensing cross-correlation is shown to be a purely geometric quantity, depending only on the distribution function of the source galaxies. By combining Planck, the Advanced Dark Energy Physics Telescope, and the Large Synoptic Survey Telescope, the ratio can be measured to ∼4% accuracy, whereas a future polarization-based experiment like CMBPOL can make a more precise (∼1%) measurement. For cosmological models where the curvature and the equation of state parameter are allowed to vary, the direction of degeneracy defined by the measurement of this ratio is different from that traced out by baryon acoustic oscillation measurements. Combining this method with the stacked cluster mass reconstruction cosmography technique as proposed by Hu, Holz, and Vale (2007), the uncertainty in the ratio can be further reduced, improving the constraints on cosmological parameters. We also study the implications of the lensing-ratio measurement for early dark energy models, in the context of the parametrization proposed by Doran and Robbers (2006). For models which are degenerate with respect to the CMB, we find both baryon acoustic oscillation and lensing-ratio measurements to be insensitive to the early component of the dark energy density.

AB - We propose a method for cosmographic measurements by combining gravitational lensing of the cosmic microwave background (CMB) with cosmic shear surveys. We cross-correlate the galaxy counts in the lens plane with two different source planes: the CMB at z∼1100 and galaxies at an intermediate redshift. The ratio of the galaxy count/CMB lensing cross-correlation to the galaxy count/galaxy lensing cross-correlation is shown to be a purely geometric quantity, depending only on the distribution function of the source galaxies. By combining Planck, the Advanced Dark Energy Physics Telescope, and the Large Synoptic Survey Telescope, the ratio can be measured to ∼4% accuracy, whereas a future polarization-based experiment like CMBPOL can make a more precise (∼1%) measurement. For cosmological models where the curvature and the equation of state parameter are allowed to vary, the direction of degeneracy defined by the measurement of this ratio is different from that traced out by baryon acoustic oscillation measurements. Combining this method with the stacked cluster mass reconstruction cosmography technique as proposed by Hu, Holz, and Vale (2007), the uncertainty in the ratio can be further reduced, improving the constraints on cosmological parameters. We also study the implications of the lensing-ratio measurement for early dark energy models, in the context of the parametrization proposed by Doran and Robbers (2006). For models which are degenerate with respect to the CMB, we find both baryon acoustic oscillation and lensing-ratio measurements to be insensitive to the early component of the dark energy density.

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U2 - 10.1103/PhysRevD.79.043509

DO - 10.1103/PhysRevD.79.043509

M3 - Article

AN - SCOPUS:62549125083

SN - 1550-7998

VL - 79

JO - Physical Review D - Particles, Fields, Gravitation and Cosmology

JF - Physical Review D - Particles, Fields, Gravitation and Cosmology

IS - 4

M1 - 043509

ER -