Formation of First Galaxies inside Density Peaks and Voids under the Influence of Dark Matter-Baryon Streaming Velocity, I: Initial Condition and Simulation Scheme

Abstract

We present a systematic study of the cosmic variance that existed in the formation of first stars and galaxies. We focus on the cosmic variance induced by the large-scale density and velocity environment engraved at the epoch of recombination. The density environment is predominantly determined by the dark-matter overdensity, and the velocity environment by the dark matter-baryon streaming velocity. Toward this end, we introduce a new cosmological initial condition generator BCCOMICS, which solves the quasi-linear evolution of small-scale perturbations under the large-scale density and streaming-velocity environment and generates the initial condition for dark matter and baryons, as either particles or grid data at a specific redshift. We also describe a scheme to simulate the formation of first galaxies inside density peaks and voids, where a local environment is treated as a separate universe. The resulting cosmic variance in the minihalo number density and the amount of cooling mass are presented as an application. Density peaks become a site for enhanced formation of first galaxies, which compete with the negative effect from the dark matter-baryon streaming velocity on structure formation.

in press for publication in ApJ; 16 pages, 7 figures, 1 table; BCCOMICS repository specified

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Cited by in corpus (10)

• The Influence of Streaming Velocities on the Formation of the First Stars
• The influence of streaming velocities and Lyman-Werner radiation on the formation of the first stars
• Robust Velocity-induced Acoustic Oscillations at Cosmic Dawn
• Cosmological advection flows in the presence of primordial black holes as dark matter and formation of first sources
• Large-scale variation in reionization history caused by Baryon-dark matter streaming velocity
• First Structure Formation under the Influence of Gas-Dark Matter Streaming Velocity and Density: Impact of the Baryons-trace-dark matter Approximation
• First estimate of the local value of the baryonic streaming velocity
• A Model-Insensitive Baryon Acoustic Oscillation Feature in the 21 cm Signal from Reionization
• Relative baryon-dark matter velocities in cosmological zoom simulations
• The influence of baryons on low-mass haloes