Planck early results. XIII. Statistical properties of extragalactic radio sources in the Planck Early Release Compact Source Catalogue^⋆

¹ Aalto University Metsähovi Radio Observatory, Metsähovintie 114, 02540 Kylmälä, Finland
² Agenzia Spaziale Italiana Science Data Center, c/o ESRIN, via Galileo Galilei, Frascati, Italy
³ Astroparticule et Cosmologie, CNRS (UMR7164), Université Denis Diderot Paris 7, Bâtiment Condorcet, 10 rue A. Domon et Léonie Duquet, Paris, France
⁴ Astrophysics Group, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK
⁵ Atacama Large Millimeter/submillimeter Array, ALMA Santiago Central Offices, Alonso de Cordova 3107, Vitacura, Casilla 763 0355, Santiago, Chile
⁶ Australia Telescope National Facility, CSIRO, PO Box 76, Epping, NSW 1710, Australia
⁷ CITA, University of Toronto, 60 St. George St., Toronto, ON M5S 3H8, Canada
⁸ CNRS, IRAP, 9 Av. Colonel Roche, BP 44346, 31028 Toulouse Cedex 4, France
⁹ California Institute of Technology, Pasadena, California, USA
¹⁰ Centre of Mathematics for Applications, University of Oslo, Blindern, Oslo, Norway
¹¹ DAMTP, University of Cambridge, Centre for Mathematical Sciences, Wilberforce Road, Cambridge CB3 0WA, UK
¹² DSM/Irfu/SPP, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
¹³ DTU Space, National Space Institute, Juliane Mariesvej 30, Copenhagen, Denmark
¹⁴ Departamento de Física, Universidad de Oviedo, Avda. Calvo Sotelo s/n, Oviedo, Spain
¹⁵ Departamento de Matemáticas, Universidad de Oviedo, Avda. Calvo Sotelo s/n, Oviedo, Spain
¹⁶ Department of Astronomy and Astrophysics, University of Toronto, 50 Saint George Street, Toronto, Ontario, Canada
¹⁷ Department of Physics & Astronomy, The Open University, Milton Keynes, MK7 6AA, UK
¹⁸ Department of Physics & Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, British Columbia, Canada
¹⁹ Department of Physics and Astronomy, University of Southern California, Los Angeles, California, USA
²⁰ Department of Physics, Gustaf Hällströmin katu 2a, University of Helsinki, Helsinki, Finland
²¹ Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, Indiana, USA
²² Department of Physics, University of California, Berkeley, California, USA
²³ Department of Physics, University of California, One Shields Avenue, Davis, California, USA
²⁴ Department of Physics, University of California, Santa Barbara, California, USA
²⁵ Department of Physics, University of Illinois at Urbana-Champaign, 1110 West Green Street, Urbana, Illinois, USA
²⁶ Dipartimento di Fisica G. Galilei, Universitàdegli Studi di Padova, via Marzolo 8, 35131 Padova, Italy
²⁷ Dipartimento di Fisica, Università La Sapienza, P. le A. Moro 2, Roma, Italy
²⁸ Dipartimento di Fisica, Università degli Studi di Milano, via Celoria, 16, Milano, Italy
²⁹ Dipartimento di Fisica, Università degli Studi di Trieste, via A. Valerio 2, Trieste, Italy
³⁰ Dipartimento di Fisica, Università di Ferrara, via Saragat 1, 44122 Ferrara, Italy
³¹ Dipartimento di Fisica, Università di Roma Tor Vergata, via della Ricerca Scientifica, 1, Roma, Italy
³² Discovery Center, Niels Bohr Institute, Blegdamsvej 17, Copenhagen, Denmark
³³ Dpto. Astrofísica, Universidad de La Laguna (ULL), 38206 La Laguna, Tenerife, Spain
³⁴ European Southern Observatory, ESO Vitacura, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago, Chile
³⁵ European Space Agency, ESAC, Planck Science Office, Camino bajo del Castillo, s/n, Urbanización Villafranca del Castillo, Villanueva de la Cañada, Madrid, Spain
³⁶ European Space Agency, ESTEC, Keplerlaan 1, 2201 AZ Noordwijk, The Netherlands
³⁷ Haverford College Astronomy Department, 370 Lancaster Avenue, Haverford, Pennsylvania, USA
³⁸ Helsinki Institute of Physics, Gustaf Hällströmin katu 2, University of Helsinki, Helsinki, Finland
³⁹ IFSI/INAF, via del Fosso Cavaliere 100, 00133, Roma, Italy
⁴⁰ INAF – Osservatorio Astrofisico di Catania, via S. Sofia 78, Catania, Italy
⁴¹ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, Padova, Italy
⁴² INAF – Osservatorio Astronomico di Roma, via di Frascati 33, Monte Porzio Catone, Italy
⁴³ INAF – Osservatorio Astronomico di Trieste, via G.B. Tiepolo 11, Trieste, Italy
⁴⁴ INAF/IASF Bologna via Gobetti 101, Bologna, Italy
⁴⁵ INAF/IASF Milano, via E. Bassini 15, Milano, Italy
⁴⁶ INRIA, Laboratoire de Recherche en Informatique, Université Paris-Sud 11, Bâtiment 490, 91405 Orsay Cedex, France
⁴⁷ IPAG: Institut de Planétologie et d’Astrophysique de Grenoble, Université Joseph Fourier, Grenoble 1/CNRS-INSU, UMR 5274, 38041 Grenoble, France
⁴⁸ ISDC Data Centre for Astrophysics, University of Geneva, Ch. d’Écogia 16, Versoix, Switzerland
⁴⁹ Imperial College London, Astrophysics group, Blackett Laboratory, Prince Consort Road, London, SW7 2AZ, UK
⁵⁰ Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA
⁵¹ Institut d’Astrophysique Spatiale, CNRS (UMR 8617) Université Paris-Sud 11, Bâtiment 121, Orsay, France
⁵² Institut d’Astrophysique de Paris, CNRS UMR 7095, Université Pierre & Marie Curie, 98bis boulevard Arago, Paris, France
⁵³ Institute of Astronomy and Astrophysics, Academia Sinica, Taipei, Taiwan
⁵⁴ Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
⁵⁵ Institute of Theoretical Astrophysics, University of Oslo, Blindern, Oslo, Norway
⁵⁶ Instituto de Astrofísica de Canarias, C/Vía Láctea s/n, La Laguna, Tenerife, Spain
⁵⁷ Instituto de Física de Cantabria (CSIC-Universidad de Cantabria), Avda. de los Castros s/n, Santander, Spain
⁵⁸ Istituto di Fisica del Plasma, CNR-ENEA-EURATOM Association, via R. Cozzi 53, Milano, Italy
⁵⁹ Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California, USA
⁶⁰ Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester, M13 9PL, UK
⁶¹ Kavli Institute for Cosmology Cambridge, Madingley Road, Cambridge, CB3 0HA, UK
⁶² LERMA, CNRS, Observatoire de Paris, 61 avenue de l’Observatoire, Paris, France
⁶³ Laboratoire AIM, IRFU/Service d’Astrophysique – CEA/DSM – CNRS – Université Paris Diderot, Bât. 709, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
⁶⁴ Laboratoire Traitement et Communication de l’Information, CNRS (UMR 5141) and Télécom ParisTech, 46 rue Barrault, 75634 Paris Cedex 13, France
⁶⁵ Laboratoire de Physique Subatomique et de Cosmologie, CNRS, Université Joseph Fourier Grenoble I, 53 rue des Martyrs, Grenoble, France
⁶⁶ Laboratoire de l’Accélérateur Linéaire, Université Paris-Sud 11, CNRS/IN2P3, Orsay, France
⁶⁷ Lawrence Berkeley National Laboratory, Berkeley, California, USA
⁶⁸ Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany
⁶⁹ MilliLab, VTT Technical Research Centre of Finland, Tietotie 3, Espoo, Finland
⁷⁰ National University of Ireland, Department of Experimental Physics, Maynooth, Co. Kildare, Ireland
⁷¹ Niels Bohr Institute, Blegdamsvej 17, Copenhagen, Denmark
⁷² Observational Cosmology, Mail Stop 367-17, California Institute of Technology, Pasadena, CA, 91125, USA
⁷³ SISSA, Astrophysics Sector, via Bonomea 265, 34136, Trieste, Italy
⁷⁴ SUPA, Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ, UK
⁷⁵ School of Physicsand Astronomy, Cardiff University, Queens Buildings, The Parade, Cardiff, CF24 3AA, UK
⁷⁶ Space Sciences Laboratory, University of California, Berkeley, California, USA
⁷⁷ Spitzer Science Center, 1200 E. California Blvd., Pasadena, California, USA
⁷⁸ Stanford University, Dept of Physics, Varian Physics Bldg, 382 via Pueblo Mall, Stanford, California, USA
⁷⁹ Université de Toulouse, UPS-OMP, IRAP, 31028 Toulouse Cedex 4, France
⁸⁰ University of Granada, Departamento de Física Teórica y del Cosmos, Facultad de Ciencias, Granada, Spain
⁸¹ University of Miami, Knight Physics Building, 1320 Campo Sano Dr., Coral Gables, Florida, USA
⁸² Warsaw University Observatory, Aleje Ujazdowskie 4, 00-478 Warszawa, Poland

Received: 8 January 2011
Accepted: 21 February 2011

Abstract

The data reported in Planck’s Early Release Compact Source Catalogue (ERCSC) are exploited to measure the number counts (dN/dS) of extragalactic radio sources at 30, 44, 70, 100, 143 and 217 GHz. Due to the full-sky nature of the catalogue, this measurement extends to the rarest and brightest sources in the sky. At lower frequencies (30, 44, and 70 GHz) our counts are in very good agreement with estimates based on WMAP data, being somewhat deeper at 30 and 70 GHz, and somewhat shallower at 44 GHz. Planck’s source counts at 143 and 217 GHz join smoothly with the fainter ones provided by the SPT and ACT surveys over small fractions of the sky. An analysis of source spectra, exploiting Planck’s uniquely broad spectral coverage, finds clear evidence of a steepening of the mean spectral index above about 70 GHz. This implies that, at these frequencies, the contamination of the CMB power spectrum by radio sources below the detection limit is significantly lower than previously estimated.