The contribution of the Warm-Hot Intergalactic Medium to the CMB anisotropies via the Sunyaev-Zeldovich effect

Abstract

Cosmological hydrodynamical simulations predict that a large fraction of all baryons reside within mildly non-linear structures with temperatures in the range $10^5-10^7$K. As the gas is highly ionized, it could be detected by the temperature anisotropies generated on the Cosmic Microwave Background radiation. We refine our previous estimates of the thermal Sunyaev-Zeldovich effect by introducing a non-polytropic equation of state to model the temperature distribution of the shock heated gas derived from temperature-density phase diagrams of different hydrodynamical simulations. Depending on the specific model, the Comptonization parameter varies in the range $10^{-7}\le y_c\le 2\times 10^{-6}$, compatible with the FIRAS upper limit. This amplitude is in agreement with a simple toy model constructed to estimate the average effect induced by filaments of ionized gas. Using the log-normal probability density function we calculate the correlation function and the power spectrum of the temperature anisotropies generated by the WHIM filaments. For a wide range of the parameter space, the maximum amplitude of the radiation power spectrum is $(\ell +1)\ell C_{\ell }/2\pi =0.7-70(\mu K{)}^2$ at $\ell \approx 200-500$. This amplitude scales with baryon density, Hubble constant and the amplitude of the matter power spectrum ${\sigma }_8$ as $[(\ell +1)\ell C_{\ell }{]}_{\max }/2\pi \propto {\sigma }_8^{2.6}({\Omega }_{b}h{)}^2$. Since the thermal Sunyaev-Zeldovich effect has a specific frequency dependence, we analyze the possibility of detecting this component with the forthcoming Planck data.

7 pages, 7 figures, Accepted for publication in MNRAS

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Cited by in corpus (6)

• Gravitational Instability of Exotic Compact Objects
• Constraining the baryon fraction in the Warm Hot Intergalactic Medium at low redshifts with PLANCK data
• Constraining the intracluster pressure profile from the thermal SZ power spectrum
• X-ray and Sunyaev-Zeldovich properties of the WHIM
• Constraints on the Sunyaev-Zel'dovich signal from the Warm Hot Intergalactic Medium from WMAP and SPT data
• Lensing and the Warm Hot Intergalactic Medium