Galaxy-CMB and galaxy-galaxy lensing on large scales: Sensitivity to primordial non-Gaussianity
- Texas Cosmology Center and Department of Astronomy, University of Texas at Austin, 1 University Station, C1400, Austin, Texas 78712 (United States)
A convincing detection of primordial non-Gaussianity in the local form of the bispectrum, whose amplitude is given by the f{sub NL} parameter, offers a powerful test of inflation. In this paper, we calculate the modification of two-point cross-correlation statistics of weak lensing--galaxy-galaxy lensing and galaxy-cosmic microwave background (CMB) crosscorrelation--due to f{sub NL}. We derive and calculate the covariance matrix of galaxy-galaxy lensing, including cosmic variance terms. We focus on large scales (l<100) for which the shape noise of the shear measurement becomes irrelevant and cosmic variance dominates the error budget. For a modest degree of non-Gaussianity, f{sub NL}={+-}50 modifications of the galaxy-galaxy-lensing signal at the 10% level are seen on scales R{approx}300 Mpc, and grow rapidly toward larger scales as {proportional_to}R{sup 2}. We also see a clear signature of the baryonic acoustic oscillation feature in the matter power spectrum at {approx}150 Mpc, which can be measured by next-generation lensing experiments. In addition, we can probe the local-form primordial non-Gaussianity in the galaxy-CMB lensing signal by correlating the lensing potential reconstructed from CMB with high-z galaxies. For example, for f{sub NL}={+-}50, we find that the galaxy-CMB lensing cross-power spectrum is modified by {approx}10% at l{approx}40, and by a factor of 2 at l{approx}10, for a population of galaxies at z=2 with a bias of 2. The effect is greater for more highly biased populations at larger z; thus, high-z galaxy surveys cross correlated with CMB offer a yet another probe of primordial non-Gaussianity.
- OSTI ID:
- 21313582
- Journal Information:
- Physical Review. D, Particles Fields, Vol. 80, Issue 12; Other Information: DOI: 10.1103/PhysRevD.80.123527; (c) 2009 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0556-2821
- Country of Publication:
- United States
- Language:
- English
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