2005 (IPP)

Permanent URI for this collectionhttp://localhost:4000/handle/11007/443

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Subject: search.filters.subject.Cosmic microwave background

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    Estimating Cosmological Parameters from CMBR : Systematic effects
    (2005-01-01) Sinha, Rita; Souradeep, Tarun
    The fluctuations in the cosmic microwave background radiation depend on the cosmological parameters. We carry out Markov Chain Monte Carlo simulations to constrain the cosmological parameter space with the current CMB data for possible systematic effects! such as beam noncircularity in CMB measurements and incomplete sky coverage.
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    Blind estimation of the power spectrum of CMB anisotropy from WMAP
    (2005-06-01) Saha, Rajib; Jain, Pankaj; Souradeep, Tarun
    Accurate measurements of angular power spectrum of Cosmic Microwave Background (CMB) radiation has lead to marked improvement in the estimates of different cosmological parameters. This has required removal of foreground contamination as well as detector noise bias with reliability and precision. We present the estimation of CMB angular power spectrum from the multi-frequency observations ofWMAP using a novel model-independent method. The primary product of WMAP are the observations of CMB in 10 independent difference assemblies (DA) that have uncorrelated noise. Our method utilizes maximum information available within WMAP data by linearly combining all the DA maps to remove foregrounds and estimating the power spectrum from cross power spectra of clean maps with independent noise. We compute 24 cross power spectra which are the basis of the final power spectrum. The binned average power matches with WMAP team’s published power spectrum closely. A small systematic difference at large multipoles is accounted for by the correction for the expected residual power from unresolved point sources. The correction is small and significantly tempered. Previous estimates have depended on foreground templates built using extraneous observational input. This is the first demonstration that the CMB angular spectrum can be reliably estimated with precision from a self contained analysis of the WMAP data.