| Title | Measurement of the Hubble Constant from X-Ray and 2.1 Millimeter Observations of Abell 2163 |
| Authors | Holzapfel, W. L.; Arnaud, M.; Ade, P. A. R.; Church, S. E.; Fischer, M. L.; Mauskopf, P. D.; Rephaeli, Y.; Wilbanks, T. M.; Lange, A. E. |
| Bibcode | 1997ApJ...480..449H Search ADS ↗ |
| Abstract | 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=1/2)=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 = 1/2) = 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=1/2)=78+60-40 km s-1 Mpc-1. |
| Objects | 1 Objects Search NED ↙ |
