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Signals of statistical anisotropy in WMAP foreground-cleaned maps

Samal, Pramoda Kumar and Saha, Rajib and Jain, Pankaj and Ralston, John P. (2009) Signals of statistical anisotropy in WMAP foreground-cleaned maps. Monthly Notices of the Royal Astronomical Society, 396 (1). pp. 511-522. ISSN 0035-8711.

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Recently, a symmetry-based method to test for statistical isotropy of the cosmic microwave background was developed. We apply the method to template-cleaned 3- and 5-years Wilkinson Microwave Anisotropy Probe-Differencing Assembly maps. We examine a wide range of angular multipoles from 2 < l < 300. The analysis detects statistically significant signals of anisotropy inconsistent with an isotropic cosmic microwave background in some of the foreground-cleaned maps. We are unable to resolve whether the anomalies have a cosmological, local astrophysical or instrumental origin. Assuming the anisotropy arises due to residual foreground contamination, we estimate the residual foreground power in the maps. For the W-band maps, we also find a highly improbable degree of isotropy we cannot explain. We speculate that excess isotropy may be caused by faulty modelling of detector noise.

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Additional Information:© 2009 The Authors. Journal compilation. © 2009 RAS. Accepted 2009 March 2. Received 2008 November 12. We acknowledge the use of Legacy Archive for Microwave Background Data Analysis. Some of the results of this work are derived using the publicly available HEALPIx package (Gorski et al. 2005). PKS acknowledges CSIR, India for financial support under the research grant CSIR-SRF-9/92(340)/2004-EMR-I. JPR is supported in part under DOE Grant Number DE-FG02-04ER14308. A portion of the research described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.
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CSIR, IndiaCSIR-SRF-9/92(340)/2004-EMR-I
Department of EnergyDE-FG02-04ER14308
Subject Keywords:methods: data analysis; cosmic microwave background; cosmology: miscellaneous
Issue or Number:1
Record Number:CaltechAUTHORS:20090908-082946715
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:15637
Deposited By: Tony Diaz
Deposited On:14 Sep 2009 16:41
Last Modified:03 Oct 2019 01:00

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