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 = 3.73-0.61+0.47 × 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) = 60-23+40 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) = 78-28+54 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) = 78-40+60 km s-1 Mpc-1.
Original language | English (US) |
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Pages (from-to) | 449-465 |
Number of pages | 17 |
Journal | Astrophysical Journal |
Volume | 480 |
Issue number | 2 PART I |
DOIs | |
State | Published - 1997 |
Externally published | Yes |
Keywords
- Cosmic microwave background
- Cosmology: observations
- Distance scale
- Galaxies: clusters: individual (Abell 2163)
- X-rays: galaxies
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science