Cosmic Microwave Background Temperature at Galaxy Clusters

Abstract

We have deduced the cosmic microwave background (CMB) temperature in the Coma cluster (A1656, $z=0.0231$), and in A2163 ($z=0.203$) from spectral measurements of the Sunyaev-Zel'dovich (SZ) effect over four passbands at radio and microwave frequencies. The resulting temperatures at these redshifts are $T_{Coma} = 2.789^{+0.080}_{-0.065}$ K and $T_{A2163} = 3.377^{+0.101}_{-0.102}$ K, respectively. These values confirm the expected relation $T(z)=T_{0}(1+z)$, where $T_{0}= 2.725 \pm 0.002$ K is the value measured by the COBE/FIRAS experiment. Alternative scaling relations that are conjectured in non-standard cosmologies can be constrained by the data; for example, if $T(z) = T_{0}(1+z)^{1-a}$ or $T(z)=T_{0}[1+(1+d)z]$, then $a=-0.16^{+0.34}_{-0.32}$ and $d = 0.17 \pm 0.36$ (at 95% confidence). We briefly discuss future prospects for more precise SZ measurements of $T(z)$ at higher redshifts.Comment: 13 pages, 1 figure, ApJL accepted for publicatio

Measurement of theTCMBevolution from the Sunyaev-Zel’dovich effect

“…with respect to the standard adiabatic evolution with T CMB = 2.726 ± 0.001 K and β = 0. (a) using data samples from Cui et al (2005); Ge et al (1997);Srianand et al (2000) and Molaro et al (2002); (b) using data samples from Srianand et al (2008) and Noterdaeme et al (2011); (c) using data samples from Muller et al (2013); (d) using data samples from Battistelli et al (2002) and Luzzi et al (2009); (e) the present analysis.…”

“…We found β = 0.006 ± 0.013. It is worth noting that (Battistelli et al 2002;Luzzi et al 2009). Dark-blue triangles represent measurements from C I and C II absorption (Cui et al 2005;Ge et al 1997;Srianand et al 2000;Molaro et al 2002) at z = (1.8, 2.0, 2.3, 3.0).…”

“…They predicted, in an optimistic case, an uncertainty on the T CMB evolution of Δβ ∼ 0.011. Actual measurements were already performed (Battistelli et al 2002;Luzzi et al 2009) and provided ΔT ≤ 0.3 K on a small number of clusters of galaxies. The Planck satellite now offers a new and large sample of galaxy clusters (Planck Collaboration 2014i) observed via the tSZ effect that allows us to derive much tighter constraints on the evolution of the CMB temperature.…”

The density, the cosmic microwave background, and the proton-to-electron mass ratio in a cloud at redshift 0.9

“…According to the standard model of cosmology, the cosmic microwave background (CMB) should follow a Planck curve of temperature T CMB = (2.725 ± 0.001) × (1 + z), with 0 ≤ z ≤ 1088 +1 −2 denoting redshift (e.g., Battistelli et al 2002;Fixsen & Mather 2002;Spergel et al 2003). Determining deviations from this relation would be a powerful tool to challenge the standard model of cosmology, highlighting possible mechanisms acting upon the photons of the cosmic microwave background (e.g., Lima et al 2000).…”

The evolution of the cosmic microwave background temperature

“…The first one relies on the measurement of a small change in the spectral intensity of the CMB towards clusters of galaxies owing to inverse Compton scattering of photons by the hot intra-cluster gas: the so-called Sunyaev-Zel'dovich (S-Z) effect (Fabbri et al 1978;Rephaeli 1980). Although this technique permits precise measurements (ΔT ∼ 0.3 K; Battistelli et al 2002;Luzzi et al 2009), the method is essentially limited to z < 0.6 because of the scarcity of known clusters at higher redshifts. The other technique uses the excitation of interstellar atomic or molecular species that have transition energies in the sub-millimetre range and can be excited by CMB photons.…”