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Frequentist comparison of CMB local extrema statistics in the five-year WMAP data with two anisotropic cosmological models

Hou, Zhen and Banday, A. J. and Górski, K. M. and Groeneboom, N. E. and Eriksen, H. K. (2010) Frequentist comparison of CMB local extrema statistics in the five-year WMAP data with two anisotropic cosmological models. Monthly Notices of the Royal Astronomical Society, 401 (4). pp. 2379-2387. ISSN 0035-8711. https://resolver.caltech.edu/CaltechAUTHORS:20100217-153020288

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Abstract

We present local extrema studies of two models that introduce a preferred direction into the observed cosmic microwave background temperature field. In particular, we make a frequentist comparison of the one- and two-point statistics for the dipole modulation and ACW models with data from the five-year Wilkinson Microwave Anisotropy Probe (WMAP). This analysis is motivated by previously revealed anomalies in the WMAP data, and particularly the difference in the statistical nature of the temperature anisotropies when analysed in hemispherical partitions. The analysis of the one-point statistics indicates that the previously determined hemispherical variance difficulties can be apparently overcome by a dipole modulation field, but new inconsistencies arise if the mean and the ℓ-dependence of the statistics are considered. The two-point correlation functions of the local extrema, ξTT (the temperature pair product) and ξPP (point–point spatial pair count), demonstrate that the impact of such a modulation is to over-'asymmetrise' the temperature field on smaller scales than the wavelength of the dipole or quadrupole, and this is disfavoured by the observed data. The results from the ACW model predictions, however, are consistent with the standard isotropic hypothesis. The two-point analysis confirms that the impact of this type of violation of isotropy on the temperature extrema statistics is relatively weak. From this work, we conclude that a model with more spatial structure than the dipole modulated or rotational-invariance breaking models are required to fully explain the observed large-scale anomalies in the WMAP data.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1111/j.1365-2966.2009.15866.xDOIUNSPECIFIED
http://www3.interscience.wiley.com/journal/123214427/abstractPublisherUNSPECIFIED
Additional Information:© 2009 The Authors. Journal compilation © 2009 RAS. Accepted 2009 October 14. Received 2009 October 13; in original form 2009 September 7. ZH acknowledges the support by Max-Planck-Gesellschaft Chinese Academy of Sciences Joint Doctoral Promotion Programme (MPG-CAS-DPP).Most of the computations were performed at the Rechenzentrum Garching (RZG) of Max-Planck-Gesellschaft and the IPP. Some of the results in this paper have been derived using the HEALPIX (G´orski et al. 2005) software and analysis package. We acknowledge use of the Legacy Archive for Microwave Background Data Analysis (LAMBDA) supported by the NASA Office of Space Science.
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Max-Planck-Gesellschaft Chinese Academy of Sciences Joint Doctoral Promotion Programme (MPG-CAS-DPP)UNSPECIFIED
Subject Keywords:methods: data analysis; cosmic microwave background
Issue or Number:4
Record Number:CaltechAUTHORS:20100217-153020288
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20100217-153020288
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17510
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:19 Feb 2010 17:57
Last Modified:03 Oct 2019 01:29

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