The Enhancement and Decrement of the Sunyaev-Zeldovich Effect toward the ROSAT Cluster RX J0658-5557
Abstract
We report simultaneous observations of the X-ray cluster RX J0658-5557 at 1.2 and 2 mm made with a double-channel photometer on the Swedish ESO Submillimeter Telescope (SEST) in search of Sunyaev-Zeldovich (SZ) effect. The SZ data were analyzed using the relativistically correct expression for the Comptonization, and we find (2.60+/-0.79)×10-4 from the detected decrement, which is consistent with that computed using the X-ray (ROSAT and ASCA) observations. The uncertainty includes contributions from statistical uncertainties in the detection, systematics, and calibration. The 1.2 mm channel data alone give rise to a larger Comptonization parameter; this result is discussed in terms of contamination from foreground sources and/or dust in the cluster or from a possible systematic effect. We then make use of a combined analysis of the ROSAT and ASCA X-ray satellite observations to determine an isothermal model for the SZ surface brightness. Since the cluster is asymmetrical and probably in a merging process, models are only approximate. The associated uncertainty can, however, be estimated by exploring a set of alternative models. We then find a factor of 1.3 for the global uncertainty on the Comptonization parameter. Combining the SZ and the X-ray measurements, we determine a value for the Hubble constant. The 2 mm data are consistent with H0(q0=1/2)=53+38-28 km s-1 Mpc-1, where the uncertainty is dominated by the uncertainty in the models of the X-ray plasma halo.
Based on observations made with the ESO-Swedish SEST 15 m telescope (La Silla, Chile).- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1999
- DOI:
- 10.1086/306830
- Bibcode:
- 1999ApJ...513...23A
- Keywords:
-
- COSMOLOGY: COSMIC MICROWAVE BACKGROUND;
- COSMOLOGY: OBSERVATIONS;
- COSMOLOGY: DISTANCE SCALE;
- GALAXIES: CLUSTERS: INDIVIDUAL (RX J0658-5557);
- X-RAYS: GALAXIES;
- Cosmology: Cosmic Microwave Background;
- Cosmology: Observations;
- Cosmology: Distance Scale;
- galaxies: clusters: individual (RX J0658-5557);
- X-Rays: Galaxies