Abstract
We have performed a sequence of high-resolution hydrodynamic simulations of structure formation in a ΛCDM model to study the thermal and kinetic Sunyaev-Zeldovich (SZ) effects. Including only adiabatic gas physics, we demonstrate that our simulations for the thermal effect are converged down to subarcminute scales. In this model, the angular power spectrum of cosmic microwave background (CMB) anisotropies induced by the thermal effect peaks at l ≃ 104, and reaches an amplitude just below current observational upper limits. Fluctuations due to the kinetic effect are a factor of ≃30 lower in power and peak at slightly smaller angular scales. We identify individual SZ sources and compute their counts as a function of source strength and angular size. We present a preliminary investigation of the consequences of an early epoch of energy injection, which tends to suppress power on small angular scales, while giving rise to additional power on large scales from the reheated intergalactic matter (IGM) at high redshift.
Highlights
The kinetic SZ effect arises from the motion of ionizedOn angular scales below 10′, the microwave sky carries the imprint of large-scale structure in the low-z universe.gas with respect to the rest-frame of the cosmic microwave background (CMB)
We have performed a sequence of high resolution hydrodynamic simulations of structure formation in a ΛCDM model to study the thermal and kinetic Sunyaev-Zel’dovich (SZ) effects
Including only adiabatic gas physics, we demonstrate that our simulations for the thermal effect are converged down to sub-arcminute scales
Summary
On angular scales below 10′, the microwave sky carries the imprint of large-scale structure in the low-z universe. Cosmic microwave background (CMB) photons propagating through the universe are inverse Compton or Doppler scattered by hot electrons along their path, b ≡ σT dl ne vr c (4). Doppler scattering induces an intensity fluctuation with the same spectral shape as the CMB itself. These effects were first described by Sunyaev & Zel’dovich (1972, 1980) and are known as the thermal and kinetic SZ effects, respectively (for recent reviews see Rephaeli 1995 and Birkinshaw 1999). The change in the (thermodynamic) temperature of the CMB resulting from scattering off non-relativistic electrons is measures the magnitude of the effect along the line of sight if vr is the radial peculiar velocity of the gas.
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