Probing cosmology with weak lensing peak counts

Journal Article · Mon Feb 15 00:00:00 EST 2010 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.81.043519· OSTI ID:21409273

Kratochvil, Jan M ^[1]; Haiman, Zoltan ^[1]; May, Morgan ^[2]

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1. Institute for Strings, Cosmology, and Astroparticle Physics (ISCAP), Columbia University, New York, New York 10027 (United States)
2. Physics Department, Brookhaven National Laboratory, Upton, New York 11973 (United States)

We propose counting peaks in weak lensing (WL) maps, as a function of their height, to probe models of dark energy and to constrain cosmological parameters. Because peaks can be identified in two-dimensional WL maps directly, they can provide constraints that are free from potential selection effects and biases involved in identifying and determining the masses of galaxy clusters. As a pilot study, we have run cosmological N-body simulations to produce WL convergence maps in three models with different constant values of the dark energy equation-of-state parameter, w=-0.8, -1, and -1.2, with a fixed normalization of the primordial power spectrum (corresponding to present-day normalizations of {sigma}{sub 8}=0.742, 0.798, and 0.839, respectively). By comparing the number of WL peaks in eight convergence bins in the range of -0.1<{kappa}<0.4, in multiple realizations of a single simulated 3x3 degree field, we show that the first (last) pair of models differ at the 95% (85%) confidence level. A survey with depth and area comparable to those expected from the Large Synoptic Survey Telescope should have a factor of {approx_equal}50 better parameter sensitivity. These results warrant further investigation, in order to assess the constraints available when marginalization over other uncertain parameters is included, and with the specifications of a realistic survey folded into the analysis. Here we find that relatively low-amplitude peaks ({kappa}{approx}0.03), which typically do not correspond to a single collapsed halo along the line of sight, account for most of the parameter sensitivity. We study a range of smoothing scales and source galaxy redshifts (z{sub s}). With a fixed source galaxy density of 15 arcmin{sup -2}, the best results are provided by the smallest scale we can reliably simulate, 1 arcmin, and z{sub s}=2 provides substantially better sensitivity than z{sub s{<=}}1.5.

• OSTI ID: 21409273
• Journal Information: Physical Review. D, Particles Fields, Vol. 81, Issue 4; Other Information: DOI: 10.1103/PhysRevD.81.043519; (c) 2010 The American Physical Society; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
CONVERGENCE
COSMOLOGY
DENSITY
EQUATIONS OF STATE
GALAXIES
GALAXY CLUSTERS
MASS
NONLUMINOUS MATTER
RED SHIFT
SENSITIVITY
SIMULATION
SPECTRA
TELESCOPES
TWO-DIMENSIONAL CALCULATIONS
EQUATIONS
MATTER
PHYSICAL PROPERTIES