Candidate high-z proto-clusters among the Planck compact sources, as revealed by Herschel-SPIRE

Greenslade, J. and Clements, D.L. and Cheng, T. and De Zotti, G. and Scott, D. and Valiante, E. and Eales, S. and Bremer, M.N. and Dannerbauer, H. and Birkinshaw, M. and Farrah, D. and Harrison, D.L. and Michałowski, M.J. and Valtchanov, I. and Oteo, I. and Baes, M. and Cooray, A. and Negrello, M. and Wang, L. and van der Werf, P. and Dunne, L. and Dye, S. (2018) Candidate high-z proto-clusters among the Planck compact sources, as revealed by Herschel-SPIRE. Monthly Notices of the Royal Astronomical Society . ISSN 1365-2966

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By determining the nature of all the Planck compact sources within 808.4 deg2 of large Herschel surveys, we have identified 27 candidate proto-clusters of dusty star forming galaxies (DSFGs) that are at least 3σ overdense in either 250, 350 or 500 μm sources. We find roughly half of all the Planck compact sources are resolved by Herschel into multiple discrete objects, with the other half remaining unresolved by Herschel. We find a significant difference between versions of the Planck catalogues, with earlier releases hosting a larger fraction of candidate proto-clusters and Galactic Cirrus than later releases, which we ascribe to a difference in the filters used in the creation of the three catalogues. We find a surface density of DSFG candidate proto-clusters of (3.3 ± 0.7) × 10−2 sources deg−2, in good agreement with previous similar studies. We find that a Planck colour selection of S857/S545 < 2 works well to select candidate proto-clusters, but can miss proto-clusters at z < 2. The Herschel colours of individual candidate proto-cluster members indicate our candidate proto-clusters all likely all lie at z > 1. Our candidate proto-clusters are a factor of 5 times brighter at 353 GHz than expected from simulations, even in the most conservative estimates. Further observations are needed to confirm whether these candidate proto-clusters are physical clusters, multiple proto-clusters along the line of sight, or chance alignments of unassociated sources.

Item Type: Article
Keywords: galaxies: clusters: general; submillimetre: galaxies; infrared: galaxies; galaxies: evolution
Schools/Departments: University of Nottingham, UK > Faculty of Science > School of Physics and Astronomy
Identification Number: 10.1093/mnras/sty023
Depositing User: Eprints, Support
Date Deposited: 08 Mar 2018 11:40
Last Modified: 08 Mar 2018 16:59

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