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تسجيل مستخدم جديدPeculiar Velocity Limits from Measurements of the Spectrum of the Sunyaev-Zeldovich Effect in Six Clusters of Galaxies
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We have made measurements of the Sunyaev-Zeldovich (SZ) effect in six galaxy clusters at z > 0.2 using the Sunyaev-Zeldovich Infrared Experiment (SuZIE II) in three frequency bands between 150 and 350 GHz. Simultaneous multi-frequency measurements have been used to distinguish between thermal and kinematic components of the SZ effect, and to significantly reduce the effects of variations in atmospheric emission which can otherwise dominate the noise. We have set limits to the peculiar velocities of each cluster with respect to the Hubble flow, and have used the cluster sample to set a 95% confidence limit of < 1410 km/s to the bulk flow of the intermediate-redshift universe in the direction of the CMB dipole. This is the first time that SZ measurements have been used to constrain bulk flows. We show that systematic uncertainties in peculiar velocity determinations from the SZ effect are likely to be dominated by submillimeter point sources and we discuss the level of this contamination.
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We present new measurements of the Sunyaev-Zeldovich (SZ) effect from clusters of galaxies using the Sunyaev-Zeldovich Infrared Experiment (SuZIE II). We combine these new measurements with previous cluster observations with the SuZIE instrument to f
orm a sample of 15 clusters of galaxies. For this sample we calculate the central Comptonization, y, and the integrated SZ flux decrement, S, for each of our clusters. We find that the integrated SZ flux is a more robust observable derived from our measurements than the central Comptonization due to inadequacies in the spatial modelling of the intra-cluster gas with a standard Beta model. This is highlighted by comparing our central Comptonization results with values calculated from measurements using the BIMA and OVRO interferometers. On average, the SuZIE calculated central Comptonizations are approximately 60% higher in the cooling flow clusters than the interferometric values, compared to only approximately 12% higher in the non-cooling flow clusters. We believe this discrepancy to be in large part due to the spatial modelling of the intra-cluster gas. From our cluster sample we construct y-T and S-T scaling relations. The y-T scaling relation is inconsistent with what we would expect for self-similar clusters; however this result is questionable because of the large systematic uncertainty in the central Comptonization. The S-T scaling relation has a slope and redshift evolution consistent with what we expect for self-similar clusters with a characteristic density that scales with the mean density of the universe. We rule out zero redshift evolution of the S-T relation at 90% confidence.
Starting from a covariant formalism of the Sunyaev-Zeldovich effect for the thermal and non-thermal distributions, we derive the frequency redistribution function identical to Wrights method assuming the smallness of the photon energy (in the Thomson
limit). We also derive the redistribution function in the covariant formalism in the Thomson limit. We show that two redistribution functions are mathematically equivalent in the Thomson limit which is fully valid for the cosmic microwave background photon energies. We will also extend the formalism to the kinematical Sunyaev-Zeldovich effect. With the present formalism we will clarify the situation for the discrepancy existed in the higher order terms of the kinematical Sunyaev-Zeldovich effect.
We present an interferometric measurement of the Sunyaev-Zeldovich effect (SZE) at 1 cm for the galaxy cluster Abell 2163. We combine this data point with previous measurements at 1.1, 1.4, and 2.1 mm from the SuZIE experiment to construct the most c
omplete SZE spectrum to date. The intensity in four wavelength bands is fit to determine the central Compton y-parameter (y_c) and the peculiar velocity (v_p) for this cluster. Our results are y_c=3.56(+0.41/-0.41)(+0.27/-0.19) x 10^-4 and v_p=410(+1030/-850)(+460/-440) km/s where we list statistical and systematic uncertainties, respectively, at 68% confidence. These results include corrections for contamination by Galactic dust emission. We find less contamination by dust emission than previously reported. The dust emission is distributed over much larger angular scales than the cluster signal and contributes little to the measured signal when the details of the SZE observing strategy are taken into account.
We study the influence of intracluster large scale magnetic fields on the thermal Sunyaev-Zeldovich (SZ) effect. In a macroscopic approach we complete the hydrostatic equilibrium equation with the magnetic field pressure component. Comparing the resu
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