Hard X-ray Emission from AGN and the Cosmic X-ray Background (CXB)

ORAL

Abstract

The CXB is believed to be caused by unresolved X-ray sources, and peaks around 30 keV. While the CXB below 20 keV is well understood, no all-sky survey has been available at the peak of the CXB before the INTEGRAL mission. Up to now more than 130 AGN have been detected by INTEGRAL above 20 keV. INTEGRAL can contribute to our understanding of the AGN phenomenon mainly in two ways. By deriving high signal to noise spectra up to several hundred keV to study the physical processes involved in this energy range, such as Compton reflection. And by looking at the statistical properties of AGN seen by INTEGRAL, one can study the contribution to the CXB and the role of heavily absorbed type II AGNs We have compiled a complete extragalactic sample based on $\sim 25,000$ square degrees in the 20-40 keV band with INTEGRAL and present the first luminosity function of AGN in this energy range. The objects explaining the peak in the cosmic X-ray background are likely to be either low luminosity AGN ($L_X < 10^{41} \rm \, ergs \, s^{-1}$) or of other type, such as intermediate mass black holes, clusters, and star forming regions. An alternative scenario is an evolution of the source population, with an increasing fraction of absorbed sources with redshift.

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Authors

  • Volker Beckmann

    ISDC and NASA/GSFC

  • Gerald Gabrielse

    Oak Ridge National Laboratory, Michigan State University, University of Maryland, Colorado School of Mines, ORAU, Tennessee Tech., University of Tennessee, ORNL, Rutgers University, Surrey, Rutgers, IFJ PAN Krakow, Rutgers, CSM, U. Tenn., Ohio U., Tenn. Tech. U., Tenn. Tech., Oak Ridge Assoc. U., Col. School of Mines, UNC - Chapel Hill, U. of Tenn., Oak Ridge Nat. Lab., Labratori Nazionali del Sud-INFN, Catania, Italy, Cyclotron Institute, Texas A\&M University, Dept. of Physics, Florida State University, U. North Carolina, Universidad de Buenos Aires, University of Texas, Lancaster University, Northwestern University, University of California, Riverside, Indiana University, Helmholtz Inst., Univ. Bonn, D-53115 Bonn, Forschungszentrum Juelich, IKP, D-52425 Juelich, Univ. of Michigan, Ann Arbor, MI 48109-1120, Department of Physics and Astronomy, Ursinus College, Pennsylvania, National Superconducting Cyclotron Laboratory, Michigan State University, Michigan, National Superconducting Cyclotron Laboratory at Michigan State University, Univ of Oslo, Mississippi St Univ, Univ. of Massachusetts-Lowell, Niels Bohr Institute, Univ of Tennessee, Argonne National Lab, Florida St Univ, US Naval Academy, A.F. Ioffe Phys. Techn. Inst., 198904 St. Petersburg, Russia, IKP, 52425 Julich, Germany; iThemba Labs, South Africa, JIHIR, Univ. of Tennessee, UNIRIB, Oak Ridge National Laboratory (supported by U.S. DOE contract \# DE-AC05-00OR22725), University of Edinburgh, Argonne National Laboratory, Department of Physics and Astronomy and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, Department of Chemistry, and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, Department of Chemistry, Michigan State University, East Lansing, MI 48824, Forschungszentrum Julich, IUSB, Hope College, Concordia College, NSCL/MSU, FSU, INP, Rez, Czech republic, Texas A\&M University, Yale University, University of North Carolina, Kyushu University, Japan, Michigan State University, USA, RCNP, Osaka, Japan, WITS, University of South Africa, Osaka University, Japan, KVI, Groningen, The Netherlands, University of Notre Dame, USA, Imperial College, Radboud University Nijmegen, LPNHE, Paris Universities VI and VII, Freiburg University, University of Michigan, University of Washington, McGill University, Brown University, Boston University, LLNL, LBNL, NSCL, MSU, NSCL \& Dept. of Chemistry, MSU, East Lansing, Dept. of Physics, FSU, Tallahassee, NSCL/Michigan State University, The Australian National University, Australian National University, Washington University, Lund University, University of Kentucky, Colorado State University, Los Alamos National Laboratory, University of South Carolina, Lawrence Berkeley National Laboratory, MPA, Germany, LSU, AEI, Germany, University of Southampton, UK, Aristotle University of Thessaloniki, Greece, Department of Physics, Florida Atlantic University, Pennsylvania State University, Andrews University, Department of Physics, Olabisi Onabanjo University, PMB 2002, Ago - Iwoye, Nigeria, University of Rochester, University of Wisconsin-Madison, University of California, Berkeley and Lawrence Berkeley National Laboratory, Observatoire de Strasbourg, Ohio University, Anglo-Australian Observatory, Rajshahi University, Rajshahi, Bangladesh, University of Rajshahi, Rajshahi, Bangladesh, MIT, M.I.T., PPPL, University of Kansas, Div. of General Education, Namseoul University, Dept. of Advanced Materials, Sunmoon University, Dept. of Computer and Applied Physics, Hanseo University, Texas A\&M University, Commerce, TUNL, University of South Dakota, LANL, Florida State University, Fermi National Accelerator Laboratory, Columbia University, Defense Trade Controls Policy, U.S. Department of State, Deutsches Elektronen-Synchrotron, Hamburg, Germany, Case Western Reserve University, American Physical Society and City College of New York, Dipartimento di Scienze Fisiche, Universita Federico II, Napoli and INFN, Napoli, Italy, Experimentalphysik III, Ruhr Universit\&#034;at Bochum, Germany, University of Connecticut, Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH), Romania, Fakult\&#034;at f\&#034;ur Physik und Astronomie, Ruhr Universit\&#034;at Bochum, Germany, Chinese Institute of Atomic Energy, Beijing, China, Experimentalphysik III, Ruhr Universit\&#034;{a}t Bochum, Germany, U. of Kostanz, McMaster U., Simon Fraser U., TRIUMF, University of Notre Dame, Yale, York, IFIN-HH, Bucharest, Romania, Department of Physics, University of North Texas, Denton, Tx 76203, Depertment of Chemistry and Biochemistry, 607 Charles E Young Dr, UCLA, Los Angeles, Ca 90095, CBH Technologies, 4727 Wilshire Blvd, Los Angeles, Ca 90010, Iowa State University, UCLA, Washington Univ., Iowa State Univ., National Knowledge Commission of India, Centre for Policy Research, Lawrence Livermore National Laboratory, Stanford University, Lockheed-Martin Corp, NVI, Inc./NASA GSFC, Harvard-Smithsonian CfA, York University, Observatoire de Paris, Erskine College, KTH, Royal Institute of Technology, NIKHEF, State University of New York, Stony Brook, University of Florida, Harvard University, UC San Diego, Northwest Analysis, Apache Point Observatory, Humboldt State University, Purdue University, Saint Joseph&#039;s College, University of Aarhus, Denmark, M. I. T., Department of Physics, University of North Carolina at Charlotte, Polish Academy of Sciences, Mississippi State University, IEP Warsaw University, IFGA, University of Milan and INFN, Vanderbilt University, Louisianna State, Warsaw University, UNIRIB/ORAU, U. of Tennessee, Mississippi State, Florida State Unversity, Flordia State University, The University of Surrey, Ivan Allen College, Georgia Institute of Technology, NPR Radio, Temple U/JLAB, U Saskatchewan, U Cyprus, U Virginia, Canadian Light Source, LPSC Grenoble, University of Texas at Dallas, The Ohio State University, INFN Ferrara, University of Oregon, Bruy\`{e}res-le-Ch\^{a}tel, T.U.Munchen, Maryland University, Miss State University, Vanderbilt, University of Liverpool, Oak Ridge Associated Universities, Tennessee Tech University, University of Oslo, University of Massachusetts, The Niels Bohr Institute, U.S. Naval Academy, CCLRC Daresbury Laboratory, United States Naval Academy, Cornell University, JLAB, Johns Hopkins University, Royal Holloway University of London, University of California at Santa Cruz, University of Rome, La Sapienza, University of California at Irvine, University of Perugia, INFN Milano, INTEGRAL Science Data Centre, NASA/GSFC, MPE, Garching, Germany, Steward Observatory, Tucson, AZ, USA, Centre d&#039;Etude Spatiale des Rayonnements, Toulouse, France, Undersecretary for Science, Department of Energy, WNSL, Yale University, University of Surrey, UK and WNSL, Yale University, University of Paris VI and VII, Massachusetts Institute of Technology, Jefferson Lab, Thomas Jefferson National Accelerator Facility, Duke University, LLNL, Univ. of Notre Dame, Univ. of Notre Dame, Union College, Algarve University, National Science Foundation, California Institution of Technology, Director, Domestic Nuclear Detection Office, Transformational R\&D Directorate, Department of Homeland Security, NASA, IFGA - University of Milan and INFN, NCSU, VT, ISU, CEA-Saclay, DSM/DAPNIA/SPhN, NGCSU \& TUNL, Sandia National Lab, Duke U. \& TUNL, Fermilab, Harvard-Smithsonian Center for Astrophysics, ICRANet and Dipartimento di Fisica - Universit\`a di Roma ``La Sapienza&#039;&#039;, Ursinus College, Purdue University Calumet, GSI, Ohio Wesleyan University, University of Cincinnati, Universidad de Antioquia, ICRA and Dipartimento di Fisica - Universit\`a di Roma ``La Sapienza&#039;&#039;, Facolt\`a di Ingegneria, Universit\`a Campus Bio-Medico, and ICRA, Facolt\`a di Ingegneria, Universit\`a Campus Bio - Medico, Istituto per le Applicazioni del Calcolo ``M. Picone&#039;&#039;, CNR, and ICRA, JPL, Pasadena, CA, 91109, NASA/GSFC Greenbelt, MD 20771, Caltech, Pasadena, CA 91125, Washington University, St. Louis, MO 63130, The Pennsylvania State University

  • Gerald Gabrielse

    Oak Ridge National Laboratory, Michigan State University, University of Maryland, Colorado School of Mines, ORAU, Tennessee Tech., University of Tennessee, ORNL, Rutgers University, Surrey, Rutgers, IFJ PAN Krakow, Rutgers, CSM, U. Tenn., Ohio U., Tenn. Tech. U., Tenn. Tech., Oak Ridge Assoc. U., Col. School of Mines, UNC - Chapel Hill, U. of Tenn., Oak Ridge Nat. Lab., Labratori Nazionali del Sud-INFN, Catania, Italy, Cyclotron Institute, Texas A\&M University, Dept. of Physics, Florida State University, U. North Carolina, Universidad de Buenos Aires, University of Texas, Lancaster University, Northwestern University, University of California, Riverside, Indiana University, Helmholtz Inst., Univ. Bonn, D-53115 Bonn, Forschungszentrum Juelich, IKP, D-52425 Juelich, Univ. of Michigan, Ann Arbor, MI 48109-1120, Department of Physics and Astronomy, Ursinus College, Pennsylvania, National Superconducting Cyclotron Laboratory, Michigan State University, Michigan, National Superconducting Cyclotron Laboratory at Michigan State University, Univ of Oslo, Mississippi St Univ, Univ. of Massachusetts-Lowell, Niels Bohr Institute, Univ of Tennessee, Argonne National Lab, Florida St Univ, US Naval Academy, A.F. Ioffe Phys. Techn. Inst., 198904 St. Petersburg, Russia, IKP, 52425 Julich, Germany; iThemba Labs, South Africa, JIHIR, Univ. of Tennessee, UNIRIB, Oak Ridge National Laboratory (supported by U.S. DOE contract \# DE-AC05-00OR22725), University of Edinburgh, Argonne National Laboratory, Department of Physics and Astronomy and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824, Department of Chemistry, and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, Department of Chemistry, Michigan State University, East Lansing, MI 48824, Forschungszentrum Julich, IUSB, Hope College, Concordia College, NSCL/MSU, FSU, INP, Rez, Czech republic, Texas A\&M University, Yale University, University of North Carolina, Kyushu University, Japan, Michigan State University, USA, RCNP, Osaka, Japan, WITS, University of South Africa, Osaka University, Japan, KVI, Groningen, The Netherlands, University of Notre Dame, USA, Imperial College, Radboud University Nijmegen, LPNHE, Paris Universities VI and VII, Freiburg University, University of Michigan, University of Washington, McGill University, Brown University, Boston University, LLNL, LBNL, NSCL, MSU, NSCL \& Dept. of Chemistry, MSU, East Lansing, Dept. of Physics, FSU, Tallahassee, NSCL/Michigan State University, The Australian National University, Australian National University, Washington University, Lund University, University of Kentucky, Colorado State University, Los Alamos National Laboratory, University of South Carolina, Lawrence Berkeley National Laboratory, MPA, Germany, LSU, AEI, Germany, University of Southampton, UK, Aristotle University of Thessaloniki, Greece, Department of Physics, Florida Atlantic University, Pennsylvania State University, Andrews University, Department of Physics, Olabisi Onabanjo University, PMB 2002, Ago - Iwoye, Nigeria, University of Rochester, University of Wisconsin-Madison, University of California, Berkeley and Lawrence Berkeley National Laboratory, Observatoire de Strasbourg, Ohio University, Anglo-Australian Observatory, Rajshahi University, Rajshahi, Bangladesh, University of Rajshahi, Rajshahi, Bangladesh, MIT, M.I.T., PPPL, University of Kansas, Div. of General Education, Namseoul University, Dept. of Advanced Materials, Sunmoon University, Dept. of Computer and Applied Physics, Hanseo University, Texas A\&M University, Commerce, TUNL, University of South Dakota, LANL, Florida State University, Fermi National Accelerator Laboratory, Columbia University, Defense Trade Controls Policy, U.S. Department of State, Deutsches Elektronen-Synchrotron, Hamburg, Germany, Case Western Reserve University, American Physical Society and City College of New York, Dipartimento di Scienze Fisiche, Universita Federico II, Napoli and INFN, Napoli, Italy, Experimentalphysik III, Ruhr Universit\&#034;at Bochum, Germany, University of Connecticut, Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH), Romania, Fakult\&#034;at f\&#034;ur Physik und Astronomie, Ruhr Universit\&#034;at Bochum, Germany, Chinese Institute of Atomic Energy, Beijing, China, Experimentalphysik III, Ruhr Universit\&#034;{a}t Bochum, Germany, U. of Kostanz, McMaster U., Simon Fraser U., TRIUMF, University of Notre Dame, Yale, York, IFIN-HH, Bucharest, Romania, Department of Physics, University of North Texas, Denton, Tx 76203, Depertment of Chemistry and Biochemistry, 607 Charles E Young Dr, UCLA, Los Angeles, Ca 90095, CBH Technologies, 4727 Wilshire Blvd, Los Angeles, Ca 90010, Iowa State University, UCLA, Washington Univ., Iowa State Univ., National Knowledge Commission of India, Centre for Policy Research, Lawrence Livermore National Laboratory, Stanford University, Lockheed-Martin Corp, NVI, Inc./NASA GSFC, Harvard-Smithsonian CfA, York University, Observatoire de Paris, Erskine College, KTH, Royal Institute of Technology, NIKHEF, State University of New York, Stony Brook, University of Florida, Harvard University, UC San Diego, Northwest Analysis, Apache Point Observatory, Humboldt State University, Purdue University, Saint Joseph&#039;s College, University of Aarhus, Denmark, M. I. T., Department of Physics, University of North Carolina at Charlotte, Polish Academy of Sciences, Mississippi State University, IEP Warsaw University, IFGA, University of Milan and INFN, Vanderbilt University, Louisianna State, Warsaw University, UNIRIB/ORAU, U. of Tennessee, Mississippi State, Florida State Unversity, Flordia State University, The University of Surrey, Ivan Allen College, Georgia Institute of Technology, NPR Radio, Temple U/JLAB, U Saskatchewan, U Cyprus, U Virginia, Canadian Light Source, LPSC Grenoble, University of Texas at Dallas, The Ohio State University, INFN Ferrara, University of Oregon, Bruy\`{e}res-le-Ch\^{a}tel, T.U.Munchen, Maryland University, Miss State University, Vanderbilt, University of Liverpool, Oak Ridge Associated Universities, Tennessee Tech University, University of Oslo, University of Massachusetts, The Niels Bohr Institute, U.S. Naval Academy, CCLRC Daresbury Laboratory, United States Naval Academy, Cornell University, JLAB, Johns Hopkins University, Royal Holloway University of London, University of California at Santa Cruz, University of Rome, La Sapienza, University of California at Irvine, University of Perugia, INFN Milano, INTEGRAL Science Data Centre, NASA/GSFC, MPE, Garching, Germany, Steward Observatory, Tucson, AZ, USA, Centre d&#039;Etude Spatiale des Rayonnements, Toulouse, France, Undersecretary for Science, Department of Energy, WNSL, Yale University, University of Surrey, UK and WNSL, Yale University, University of Paris VI and VII, Massachusetts Institute of Technology, Jefferson Lab, Thomas Jefferson National Accelerator Facility, Duke University, LLNL, Univ. of Notre Dame, Univ. of Notre Dame, Union College, Algarve University, National Science Foundation, California Institution of Technology, Director, Domestic Nuclear Detection Office, Transformational R\&D Directorate, Department of Homeland Security, NASA, IFGA - University of Milan and INFN, NCSU, VT, ISU, CEA-Saclay, DSM/DAPNIA/SPhN, NGCSU \& TUNL, Sandia National Lab, Duke U. \& TUNL, Fermilab, Harvard-Smithsonian Center for Astrophysics, ICRANet and Dipartimento di Fisica - Universit\`a di Roma ``La Sapienza&#039;&#039;, Ursinus College, Purdue University Calumet, GSI, Ohio Wesleyan University, University of Cincinnati, Universidad de Antioquia, ICRA and Dipartimento di Fisica - Universit\`a di Roma ``La Sapienza&#039;&#039;, Facolt\`a di Ingegneria, Universit\`a Campus Bio-Medico, and ICRA, Facolt\`a di Ingegneria, Universit\`a Campus Bio - Medico, Istituto per le Applicazioni del Calcolo ``M. Picone&#039;&#039;, CNR, and ICRA, JPL, Pasadena, CA, 91109, NASA/GSFC Greenbelt, MD 20771, Caltech, Pasadena, CA 91125, Washington University, St. Louis, MO 63130, The Pennsylvania State University