Detection of a supervoid aligned with the cold spot of the cosmic microwave background
István Szapudi1,★, András Kovács2,3,4, Benjamin R. Granett5, Zsolt Frei2,3, Joseph Silk6, Will Burgett1, Shaun Cole7, Peter W. Draper7, Daniel J. Farrow7, Nicholas Kaiser1, Eugene A. Magnier1, Nigel Metcalfe7, Jeffrey S. Morgan1, Paul Price8, John Tonry1 and Richard Wainscoat1
- Author Affiliations
1Institute for Astronomy, University of Hawaii 2680 Woodlawn Drive, Honolulu, HI 96822, USA
2Institute of Physics, Eötvös Loránd University, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary
3MTA-ELTE EIRSA ‘Lendület’ Astrophysics Research Group, Pázmány Péter sétány 1/A, 1117 Budapest, Hungary
4Institut de Física d'Altes Energies, Universitat Autónoma de Barcelona, E-08193 Bellaterra (Barcelona), Spain
5INAF OA Brera, Via E. Bianchi 46, I-23807 Merate, Italy
6Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, MD 21218, USA
7Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
8Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544, USA
↵★E-mail: szapudi@ifa.hawaii.edu
- Accepted 2015 March 4.
- Received 2015 February 24.
- In original form 2014 May 6.
- First published online April 19, 2015.
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Abstract
We use the WISE-2MASS infrared galaxy catalogue matched with Pan-STARRS1 (PS1) galaxies to search for a supervoid in the direction of the cosmic microwave background (CMB) cold spot (CS). Our imaging catalogue has median redshift z ≃ 0.14, and we obtain photometric redshifts from PS1 optical colours to create a tomographic map of the galaxy distribution. The radial profile centred on the CS shows a large low-density region, extending over tens of degrees. Motivated by previous CMB results, we test for underdensities within two angular radii, 5°, and 15°. The counts in photometric redshift bins show significantly low densities at high detection significance, ≳5σ and ≳6σ, respectively, for the two fiducial radii. The line-of-sight position of the deepest region of the void is z ≃ 0.15–0.25. Our data, combined with an earlier measurement by Granett, Szapudi & Neyrinck, are consistent with a largeRvoid = (220 ± 50) h−1 Mpc supervoid with δm ≃ −0.14 ± 0.04 centred at z = 0.22 ± 0.03. Such a supervoid, constituting at least a ≃3.3σ fluctuation in a Gaussian distribution of the Λ cold dark matter model, is a plausible cause for the CS.
Key words
- © 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
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