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Non-Gaussianity in the Very Small Array cosmic microwave background maps with smooth goodness-of-fit tests

Rubiño-Martín, José Alberto and Aliaga, Antonio M. and Barreiro, R. B. and Battye, Richard A. and Carreira, Pedro and Cleary, Kieran and Davies, Rod D. and Davis, Richard J. and Dickinson, Clive and Genova-Santos, Ricardo and Grainge, Keith and Gutiérrez, Carlos M. and Hafez, Yaser A. and Hobson, Michael P. and Jones, Michael E. and Kneissl, Rüdiger and Lancaster, Katy and Lasenby, Anthony and Leahy, J. P. and Maisinger, Klaus and Martínez-González, Enrique and Pooley, Guy G. and Rajguru, Nutan and Rebolo, Rafael and Sanz, José Luis and Saunders, Richard D. E. and Savage, Richard S. and Scaife, Anna and Scott, Paul and Slosar, Anže and Taylor, Angela C. and Titterington, David and Waldram, Elizabeth and Watson, Robert A. (2006) Non-Gaussianity in the Very Small Array cosmic microwave background maps with smooth goodness-of-fit tests. Monthly Notices of the Royal Astronomical Society, 369 (2). pp. 909-920. ISSN 0035-8711.

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We have used the Rayner and Best smooth tests of goodness-of-fit to study the Gaussianity of the Very Small Array (VSA) data. These tests are designed to be sensitive to the presence of ‘smooth’ deviations from a given distribution, and are applied to the data transformed into normalized signal-to-noise eigenmodes. In a previous work, they have been already adapted and applied to simulated observations of interferometric experiments. In this paper, we extend the practical implementation of the method to deal with mosaiced observations, by introducing the Arnoldi algorithm. This method permits us to solve large eigenvalue problems with low computational cost. Out of the 41 published VSA individual pointings dedicated to cosmological [cosmic microwave background (CMB)] observations, 37 are found to be consistent with Gaussianity, whereas four pointings show deviations from Gaussianity. In two of them, these deviations can be explained as residual systematic effects of a few visibility points which, when corrected, have a negligible impact on the angular power spectrum. The non-Gaussianity found in the other two (adjacent) pointings seems to be associated to a local deviation of the power spectrum of these fields with respect to the common power spectrum of the complete data set, at angular scales of the third acoustic peak (ℓ = 700–900). No evidence of residual systematics is found in this case, and unsubtracted point sources are not a plausible explanation either. If those visibilities are removed, the differences of the new power spectrum with respect to the published one only affect three bins. A cosmological analysis based on this new VSA power spectrum alone shows no differences in the parameter constraints with respect to our published results, except for the physical baryon density, which decreases by 10 per cent. Finally, the method has been also used to analyse the VSA observations in the Corona Borealis supercluster region. Our method finds a clear deviation (99.82 per cent) with respect to Gaussianity in the second-order moment of the distribution, and which cannot be explained as systematic effects. A detailed study shows that the non-Gaussianity is produced in scales of ℓ ≈ 500, and that this deviation is intrinsic to the data (in the sense that cannot be explained in terms of a Gaussian field with a different power spectrum). This result is consistent with the Gaussianity studies in the Corona Borealis data presented in Génova-Santos et al. which show a strong decrement that cannot be explained as primordial CMB.

Item Type:Article
Related URLs:
URLURL TypeDescription
Rubiño-Martín, José Alberto0000-0001-5289-3021
Barreiro, R. B.0000-0002-6139-4272
Battye, Richard A.0000-0002-4269-515X
Dickinson, Clive0000-0002-0045-442X
Genova-Santos, Ricardo0000-0001-5479-0034
Grainge, Keith0000-0002-6780-1406
Jones, Michael E.0000-0003-3564-6680
Lancaster, Katy0000-0001-7296-128X
Lasenby, Anthony0000-0002-8208-6332
Rebolo, Rafael0000-0003-3767-7085
Savage, Richard S.0000-0003-3317-1036
Scaife, Anna0000-0002-5364-2301
Slosar, Anže0000-0002-8713-3695
Additional Information:© 2006 The Authors. Journal compilation © 2006 RAS. Accepted 2006 March 17. Received 2006 February 9; in original form 2005 November 4. Published: 26 May 2006. We thank the staff of the Mullard Radio Astronomy Observatory, the Jodrell Bank Observatory and the Teide Observatory for invaluable assistance in the commissioning and operation of the VSA. The VSA is supported by PPARC and the IAC. Partial financial support was provided by the Spanish Ministry of Science and Technology project AYA2001-1657. We also acknowledge the Spanish project ESP2004-07067-C03-01.
Funding AgencyGrant Number
Particle Physics and Astronomy Research Council (PPARC)UNSPECIFIED
Instituto de Astrofisica de Canarias (IAC)UNSPECIFIED
Ministerio de Ciencia e Innovación (MCINN)AYA2001-1657
Ministerio de Ciencia e Innovación (MCINN)ESP2004-07067-C03-01
Subject Keywords:methods: data analysis – methods: statistical – cosmic microwave background – cosmology: observations
Issue or Number:2
Record Number:CaltechAUTHORS:20210309-150757078
Persistent URL:
Official Citation:José Alberto Rubiño-Martín, Antonio M. Aliaga, R. B. Barreiro, Richard A. Battye, Pedro Carreira, Kieran Cleary, Rod D. Davies, Richard J. Davis, Clive Dickinson, Ricardo Génova-Santos, Keith Grainge, Carlos M. Gutiérrez, Yaser A. Hafez, Michael P. Hobson, Michael E. Jones, Rüdiger Kneissl, Katy Lancaster, Anthony Lasenby, J. P. Leahy, Klaus Maisinger, Enrique Martínez-González, Guy G. Pooley, Nutan Rajguru, Rafael Rebolo, José Luis Sanz, Richard D. E. Saunders, Richard S. Savage, Anna Scaife, Paul Scott, Anže Slosar, Angela C. Taylor, David Titterington, Elizabeth Waldram, Robert A. Watson, Non-Gaussianity in the Very Small Array cosmic microwave background maps with smooth goodness-of-fit tests, Monthly Notices of the Royal Astronomical Society, Volume 369, Issue 2, June 2006, Pages 909–920,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108372
Deposited By: Tony Diaz
Deposited On:10 Mar 2021 20:31
Last Modified:10 Mar 2021 20:31

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