Probing dark matter caustics with weak lensing

Abstract

Caustics are high-density structures that form frequently in collisionless media. Under self-gravity, cold dark matter flows focus onto caustics which are yet to be resolved in numerical simulations and or observed in the real world. If detected, caustics would provide a strong evidence for dark matter and would rule out alternative models such as those with modified dynamics. Here, we demonstrate how they might be observed in the weak lensing data. We evaluate the shear distortion and show that its radial profile is marked by a characteristic sawtooth pattern due to the caustics in dark matter haloes that form by selfsimilar accretion. We discuss the observational complications, mainly due to the poor knowledge of the virial radii of the haloes and demonstrate that a superposition of about 300 cluster-size haloes would give a signal-to-noise ratio which is sufficiently large for the detection of caustics with ground-based observations. This number is reduced to 100 for space-based observations. These bounds can be easily achieved by the ongoing wide field optical surveys such as CFHTLS and the future space-based projects SNAP and DUNE which have to be accompanied by a X-ray follow-up of the selected clusters for a precise determination of their virial radii.

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Cited by in corpus (11)

• The Caustic Ring Model of the Milky Way Halo
• Satellite Galaxies and Fossil Groups in the Millennium Simulation
• Caustics in growing Cold Dark Matter Haloes
• Dark matter caustics and the enhancement of self-annihilation flux
• A further look at particle annihilation in dark matter caustics
• Hierarchical Phase Space Structure of Dark Matter Haloes: Tidal debris, Caustics, and Dark Matter annihilation
• WIMP annihilation in caustics
• Gravitational Lensing and Structural Stability of Dark Matter Caustic Rings
• Caustics, cold flows, and annual modulation
• Anisotropy and characteristic scales in halo density gradient profiles
• Probing Cold Dark Matter Cusps by Gravitational Lensing