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Measurement of the Hubble constant from X-Ray and 2.1 millimeter observations of Abell 2163

Holzapfel, W. L., Arnaud, M., Ade, Peter A. R., Church, S. E., Fischer, M. L., Mauskopf, Philip Daniel, Rephaeli, Y., Wilbanks, T. M. and Lange, A. E. 1997. Measurement of the Hubble constant from X-Ray and 2.1 millimeter observations of Abell 2163. The Astrophysical Journal 480 (2) , pp. 449-465. 10.1086/303979

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We report 2.1 mm observations of the Sunyaev-Zeldovich (S-Z) effect; these observations confirm our previous detection of a decrement in the cosmic microwave background intensity toward the cluster Abell 2163. The S-Z data are analyzed using the relativistically correct expression for the Comptonization. We begin by assuming the intracluster (IC) gas to be isothermal at the emission-weighted average temperature determined by a combined analysis of the ASCA and Ginga X-ray satellite observations. The results of ROSAT/PSPC observations are used to determine an isothermal model for the S-Z surface brightness. Fitting to this model, we determine the peak Comptonization to be y0 = 3.73+ 0.47−0.61×10−4. The uncertainty includes contributions due to statistical uncertainty in the detection, instrumental baseline, calibration, and density model. Combining the X-ray and S-Z measurements, we determine the Hubble constant to be H0(q0=½)=60+ 40−23 km s-1 Mpc-1, where the uncertainty is dominated by the systematic difference in the ASCA- and Ginga-determined IC gas temperatures. ASCA observations suggest the presence of a significant thermal gradient in the IC gas. We determine H0 as a function of the assumed IC gas thermal structure. Using the ASCA-determined thermal structure and keeping the emission-weighted average temperature the same as in the isothermal case, we find H0(q0 = ½) = 78+ 54−28 km s-1 Mpc-1. Including additional uncertainties due to cluster asphericity, peculiar velocity, IC gas clumping, and astrophysical confusion, we find H0(q0=½)=78+ 60−40 km s-1 Mpc-1.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Subjects: Q Science > QB Astronomy
Publisher: IOP Publishing
ISSN: 0004-637X
Last Modified: 23 Jan 2020 04:01

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