The Structure of Cosmic String Wakes

Abstract

The clustering of baryons and cold dark matter induced by a single moving string is analyzed numerically making use of a new three-dimensional Eulerian cosmological hydro code${}^{1)}$ which is based on the PPM method to track the baryons and the PIC method to evolve the dark matter particles. A long straight string moving with a speed comparable to $c$ induces a planar overdensity (a``wake"). Since the initial perturbation is a velocity kick towards the plane behind the string and there is no initial Newtonian gravitational line source, the baryons are trapped in the center of the wake, leading to an enhanced baryon to dark matter ratio. The cold coherent flow leads to very low post--shock temperatures of the baryonic fluid. In contrast, long strings with a lot of small-scale structure (which can be described by adding a Newtonian gravitational line source) move slowly and form filamentary objects. The large central pressure due to the gravitational potential causes the baryons to be expelled from the central regions and leads to a relative deficit in the baryon to dark matter ratio. In this case, the velocity of the baryons is larger, leading to high post-shock temperatures.

36 pages (including 19 figures), TeX (with phyzzx) type, mpeg simulations available at http://www.damtp.cam.ac.uk/user/ats25/

References in corpus (3)

• Large Angular Scale CMB Anisotropy Induced by Cosmic Strings
• Accretion of Cold and Hot Dark Matter onto Cosmic String Filaments
• An Eulerian PPM & PIC Code for Cosmological Hydrodynamics

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• Lensing and CMB Anisotropies by Cosmic Strings at a Junction
• The 21 cm Signature of Shock Heated and Diffuse Cosmic String Wakes
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• Searching for Signatures of Cosmic String Wakes in 21cm Redshift Surveys using Minkowski Functionals
• Disruption of Cosmic String Wakes by Gaussian Fluctuations
• Extracting the Signal of Cosmic String Wakes from 21-cm Observations
• Note on Structure Formation from Cosmic String Wakes
• The bispectrum of matter perturbations from cosmic strings
• Reionization by active sources and its effects on the cosmic microwave background
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• The Flow Around a Cosmic String, Part I: Hydrodynamic Solution
• Particle motion in weak relativistic gravitational fields
• Primordial Non-Gaussianity: Baryon Bias and Gravitational Collapse of Cosmic String Wakes
• Inflation, Topological Defects and Baryogenesis: Selected Topics at the Interface between Particles & Fields and Cosmology
• Magnetic field amplification and decay in cosmic string wakes
• The Structure of Cosmic String Wakes (Proceedings)