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Register a new userMeasurement of the $T_{rm CMB}$ evolution from the Sunyaev-Zeldovich effect
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Hurier Guillaume Dr
Publication date
2013
fields
Physics
and research's language is
English
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In the standard hot cosmological model, the black-body temperature of the Cosmic Microwave Background (CMB), $T_{rm CMB}$, increases linearly with redshift. Across the line of sight CMB photons interact with the hot ($sim10^{7-8}$ K) and diffuse gas of electrons from galaxy clusters. This interaction leads to the well known thermal Sunyaev-Zeldovich effect (tSZ), which produces a distortion of the black-body emission law, depending on $T_{rm CMB}$. Using tSZ data from the ${it Planck}$ satellite it is possible to constrain $T_{rm CMB}$ below z=1. Focusing on the redshift dependance of $T_{rm CMB}$ we obtain $T_{rm CMB}(z)=(2.726pm0.001)times (1+z)^{1-beta}$ K with $beta=0.009pm0.017$, improving previous constraints. Combined with measurements of molecular species absorptions, we derive $beta=0.006pm0.013$. These constraints are consistent with the standard (i.e. adiabatic, $beta=0$) Big-Bang model.
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The Sunyaev-Zeldovich (SZ) effect introduces a specific distortion of the blackbody spectrum of the cosmic microwave background (CMB) radiation when it scatters off hot gas in clusters of galaxies. The frequency dependence of the distortion is only independent of the cluster redshift when the evolution of the CMB radiation is adiabatic. Using 370 clusters within the redshift range $0.07lesssim zlesssim1.4$ from the largest SZ-selected cluster sample to date from the Atacama Cosmology Telescope, we provide new constraints on the deviation of CMB temperature evolution from the standard model $alpha=0.017^{+0.029}_{-0.032}$, where $T(z)=T_0(1+z)^{1-alpha}$. This result is consistent with no deviation from the standard adiabatic model. Combining it with previous, independent datasets we obtain a joint constraint of $alpha=-0.001pm0.012$.
We propose a new analysis of small scale CMB data by introducing the cosmological dependency of the foreground signals, focusing first on the thermal Sunyaev-Zeldovich (tSZ) power spectrum, derived from the halo model. We analyse the latest observations by the South Pole Telescope (SPT) of the high-$ell$ power (cross) spectra at 90, 150 and 220 GHz, as the sum of CMB and tSZ signals, both depending on cosmological parameters, and remaining contaminants. In order to perform faster analyses, we propose a new tSZ modelling based on machine learning algorithms (namely Random Forest). We show that the additional information contained in the tSZ power spectrum tightens constraints on cosmological and tSZ scaling relation parameters. We combine for the first time the Planck tSZ data with SPT high-$ell$ to derive even stronger constraints. Finally, we show how the amplitude of the remaining kSZ power spectrum varies depending on the assumptions made on both tSZ and cosmological parameters.
We present a detection of the unnormalized skewness <T^3> induced by the thermal Sunyaev-Zeldovich (tSZ) effect in filtered Atacama Cosmology Telescope (ACT) 148 GHz cosmic microwave background temperature maps. Contamination due to infrared and radio sources is minimized by template subtraction of resolved sources and by constructing a mask using outlying values in the 218 GHz (tSZ-null) ACT maps. We measure <T^3>= -31 +- 6 mu K^3 (measurement error only) or +- 14 mu K^3 (including cosmic variance error) in the filtered ACT data, a 5-sigma detection. We show that the skewness is a sensitive probe of sigma_8, and use analytic calculations and tSZ simulations to obtain cosmological constraints from this measurement. From this signal alone we infer a value of sigma_8= 0.79 +0.03 -0.03 (68 % C.L.) +0.06 -0.06 (95 % C.L.). Our results demonstrate that measurements of non-Gaussianity can be a useful method for characterizing the tSZ effect and extracting the underlying cosmological information.
We consider the effect of the cosmic microwave background (CMB) frequency spectral distortions arising due to the Compton scattering of the anisotropic radiation on Sunyaev-Zeldovich (SZ) clusters. We derive the correction to the thermal SZ effect due to the presence of multipoles with $ell=1,2,3$ in the anisotropy of the CMB radiation. We show that this effect gives us an opportunity for an independent evaluation of the CMB dipole, quadrupole and octupole angular anisotropy in our location using distorted signal from the nearby galaxy clusters and to distinguish between the Sachs-Wolfe (SW) and the Integrated Sachs-Wolfe (ISW) effects by combining such signals from distant and nearby clusters. The future space mission Millimetron will have unprecedented sensitivity, which will make it possible to observe the spectral distortion we are considering.
The epoch of reionization is one of the major phase transitions in the history of the universe, and is a focus of ongoing and upcoming cosmic microwave background (CMB) experiments with improved sensitivity to small-scale fluctuations. Reionization also represents a significant contaminant to CMB-derived cosmological parameter constraints, due to the degeneracy between the Thomson-scattering optical depth, $tau$, and the amplitude of scalar perturbations, $A_s$. This degeneracy subsequently hinders the ability of large-scale structure data to constrain the sum of the neutrino masses, a major target for cosmology in the 2020s. In this work, we explore the kinematic Sunyaev-Zeldovich (kSZ) effect as a probe of reionization, and show that it can be used to mitigate the optical depth degeneracy with high-sensitivity, high-resolution data from the upcoming CMB-S4 experiment. We discuss the dependence of the kSZ power spectrum on physical reionization model parameters, as well as on empirical reionization parameters, namely $tau$ and the duration of reionization, $Delta z$. We show that by combining the kSZ two-point function and the reconstructed kSZ four-point function, degeneracies between $tau$ and $Delta z$ can be strongly broken, yielding tight constraints on both parameters. We forecast $sigma(tau) = 0.003$ and $sigma(Delta z) = 0.25$ for a combination of CMB-S4 and Planck data, including detailed treatment of foregrounds and atmospheric noise. The constraint on $tau$ is nearly identical to the cosmic-variance limit that can be achieved from large-angle CMB polarization data. The kSZ effect thus promises to yield not only detailed information about the reionization epoch, but also to enable high-precision cosmological constraints on the neutrino mass.
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