Obscured clusters
نویسندگان
چکیده
منابع مشابه
Obscured Active Galactic Nuclei and Obscured Accretion
Most of the local active galactic nucleus (AGN) population is obscured and much of the Xray background originates in obscured AGNs. The contribution of obscured accretion to the growth of massive black holes is discussed here. The recent identification of significant samples of the X-ray sources that dominate the X-ray background intensity has shown a redshift peak at 0.7–0.8, rather than the r...
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The current census of, and stellar population in, massive Galactic star clusters is reviewed. In particular, we concentrate on a recent survey of obscured Galactic Giant H II (GHII) regions and the associated stellar clusters embedded in them. The regions have been selected as the most luminous radio continuum sources, and as such the stellar clusters appear to be among the youngest massive clu...
متن کاملObscured Active Galactic Nuclei
The properties of the absorption in type 2, narrow line AGNs are reviewed by focusing on the X-ray indicators. I discuss the properties of the cold absorbing medium (the putative torus) and of the reprocessed components, as well as their implications for the unified model. The relation between optical classification and X-ray absorption is examined. The case of “fossil” AGNs, whose type 2 class...
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Using mid-infrared and radio criteria, we select a sample of candidate z ∼ 2 obscured quasars. Optical spectroscopy confirms about half of these as type-2 quasars, and modelling the population suggests 50-80% of the quasars are obscured. We find some flat radio spectrum type-2 quasars, and tentative evidence for obscuration unrelated to the torus. Using a similar sample, we also find evidence f...
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Auger results on clustering of > ∼ 60 EeV ultra-high energy cosmic ray (UHECR) ions and the interpretation of the γ-ray spectra of TeV blazars are connected by effects from the extragalactic background light (EBL). The EBL acts as an obscuring medium for γ rays and a reprocessing medium for UHECR ions and protons, causing the GZK cutoff. The study of the physics underlying the coincidence betwe...
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ژورنال
عنوان ژورنال: Astronomy and Astrophysics
سال: 2010
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361/200913122