Obscured AGN and the X-ray background |
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| Institution: | 1. Institute for Astronomy, Blackford Hill, Edinburgh EH9 3HJ, Scotland;1. Center for Alzheimer’s and Related Dementias (CARD), National Institute on Aging and National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20814, USA;2. Data Tecnica LLC, Washington, DC 20037, USA;3. Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, MD 20814, USA;4. Department of Clinical and Movement Neurosciences, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK;5. UCL Movement Disorders Centre, University College London, London WC1N 3BG, UK;6. German Center for Neurodegenerative Diseases (DZNE), Tübingen, Germany;1. Department of Earth Sciences (Geochemistry), Faculty of Geosciences, Utrecht University, P.O. Box 80.021, 3508 TA Utrecht, The Netherlands;2. Department of Estuarine and Delta Systems, Royal Netherlands Institute for Sea Research, Yerseke, The Netherlands;3. Dutch-Belgian Beamline (DUBBLE), ESRF – The European Synchrotron, CS 40220, 38043 Grenoble Cedex 9, France;4. Department of Analytical, Environmental- and Geo-chemistry, Vrije Universiteit Brussel (VUB), Pleinlaan 2, 1050 Brussels, Belgium;1. Universidad de Castilla-La Mancha, Faculty of Pharmacy, Calle Almansa 14 – Edif. Bioincubadora, 02008, Albacete, Spain;2. Ruprecht-Karls-Universität Heidelberg, Organisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120, Heidelberg, Germany;1. Department of Microbiology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran;2. Venom and Biotherapeutics Molecules Lab, Medical Biotechnology Department, Biotechnology Research Center, Pasteur Institute of Iran, Tehran, Iran;3. Department of Biology, Sofian Branch, Islamic Azad University, Sofian, Iran;4. Department of Microbiology, North Tehran Branch, Islamic Azad University, Tehran, Iran;5. Gastrointestinal and Liver Diseases Research Center, Iran University of Medical Sciences, Tehran, Iran;6. Department of Biochemistry, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran;7. Research Center for Molecular Medicine, Hamadan University of Medical Sciences, Hamadan, Iran;8. Department of Virology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran |
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| Abstract: | There is growing evidence that the hard X-ray background (XRB) can be explained by a large population of obscured AGN. I review some of the results of recent deep X-ray surveys, and in particular I discuss the nature of the X-ray luminous emission-line galaxies which have emerged at the faintest X-ray fluxes. If obscured AGN do explain the XRB, a direct implication is that the majority of the energy produced by accretion in the universe is absorbed and not emitted directly. Deep submillimetre surveys with SCUBA have recently attracted a lot of attention, with the potential to allow us an unobscured view dust-enshrouded starformation at high redshift. It has generally been assumed that these sources are purely high redshift starforming galaxies, but if models for the XRB are correct then a significant fraction (∼20%) could contain a luminous AGN. |
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