54619228
Joint reconstruction of galaxy clusters from gravitational lensing and thermal gas - I. Outline of a non-parametric method
We present a method to estimate the lensing potential from massive galaxy clusters for given observational X-ray data. The concepts developed and applied in this work can easily be combined with other techniques to infer the lensing potential, e.g. weak gravitational lensing or galaxy kinematics, to obtain an overall best fit model for the lensing potential. After elaborating on the physical details and assumptions the method is based on, we explain how the numerical algorithm itself is implemented with a Richardson-Lucy algorithm as a central part. Our reconstruction method is tested on simulated galaxy clusters with a spherically symmetric NFW density profile filled with gas in hydrostatic equilibrium. We describe in detail how these simulated observational data sets are created and how they need to be fed into our algorithm. We test the robustness of the algorithm against small parameter changes and estimate the quality of the reconstructed lensing potentials. As it turns out we achieve a very high degree of accuracy in reconstructing the lensing potential. The statistical errors remain below 2.0% whereas the systematical error does not exceed 1.0%.
118653169
Joint reconstruction of galaxy clusters from gravitational lensing and thermal gas II. Inversion of the thermal Sunyaev-Zel'dovich effect
This paper continues a series in which we intend to show how all observables of galaxy clusters can be combined to recover the twodimensional, projected gravitational potential of individual clusters. Our goal is to develop a non-parametric algorithm for joint cluster reconstruction taking all cluster observables into account. In this paper, we begin with the relation between the Compton-y parameter and the Newtonian gravitational potential, assuming hydrostatic equilibrium and a polytropic stratification of the intracluster gas. We show how Richardson-Lucy deconvolution can be used to convert the intensity change of the CMB due to the thermal SunyaevZel’dovich e ect into an estimate for the two-dimensional gravitational potential. Synthetic data simulated with characteristics of the ALMA telescope show that the two-dimensional potential of a cluster with mass 5 10 14 h 1 M at redshift 0:2 is possible with an error of . 5 % between the cluster centre and a radius r . 0:9h 1 Mpc.
9905254
Three-Year Wilkinson Microwave Anisotropy Probe (WMAP)* Observations: Beam Profiles, Data Processing, Radiometer Characterization, and Systematic Error Limits
The WMAP satellite has completed 3 years of observations of the cosmic microwave background radiation. The 3yeardataproductsincludeseveralsetsof fullskymapsoftheStokesI,Q,andUparametersinfivefrequencybands, spanning 23Y94 GHz, and supporting items such as beam window functions and noise covariance matrices. The processing used to produce the current sky maps and supporting products represents a significant advancement over the first-year analysis and is described herein. Improvements to the pointing reconstruction, radiometer gain modeling, window function determination, and radiometer spectral noise parameterization are presented. A detailed description of the updated data processing that produces maximum likelihood sky map estimates is presented, along withthemethodsusedtoproducereducedresolutionmapsandcorrespondingnoisecovariancematrices.Finally,two methods used to evaluate the noise of the full resolution sky maps are presented along with several representativeyear-to-yearnulltests,demonstratingthatskymapsproducedfromdatafromdifferentobservationalepochsare consistent. Subject headingg cosmic microwave background — instrumentation: detectors — space vehicles: instruments
119071757
First-Year Wilkinson Microwave Anisotropy Probe (WMAP)* Observations: Galactic Signal Contamination from Sidelobe Pickup
Since the Galactic center is ~1000 times brighter than fluctuations in the cosmic microwave background (CMB), CMB experiments must carefully account for stray Galactic pickup. We present the level of contamination due to sidelobes for the first-year CMB maps produced by the Wilkinson Microwave Anisotropy Probe (WMAP) observatory. For each radiometer, full 4π sr antenna gain patterns are determined from a combination of numerical prediction and ground-based and space-based measurements. These patterns are convolved with the WMAP first-year sky maps and observatory scan pattern to generate the expected sidelobe signal contamination, for both intensity and polarized microwave sky maps. When the main beams are outside of the Galactic plane, we find rms values for the expected sidelobe pickup of 15, 2.1, 2.0, 0.3, and 0.5 μK for the K, Ka, Q, V, and W bands, respectively. Except for at the K band, the rms polarized contamination is 1 μK. Angular power spectra of the Galactic pickup are presented.
14291665
THE SPECTRUM OF INTEGRATED MILLIMETER FLUX OF THE MAGELLANIC CLOUDS AND 30 DORADUS FROM TOPHAT AND DIRBE DATA
We present measurements of the integrated flux relative to the local background of the Large and Small Magellanic Clouds and the region 30 Doradus (the Tarantula Nebula) in the LMC in four frequency bands centered at 245, 400, 460, and 630 GHz, based on observations made with the TopHat telescope. We combine these observations with the corresponding measurements for the DIRBE bands 8, 9, and 10 to cover the frequency range 245-3000 GHz (100-1220 μm) for these objects. We present spectra for all three objects and fit these spectra to a single-component graybody emission model and report best-fit dust temperatures, optical depths, and emissivity power-law indices, and we compare these results with other measurements in these regions and elsewhere. Using published dust grain opacities, we estimate the mass of the measured dust component in the three regions.