منابع مشابه
X-ray Observations of AGN at Intermediate to High Redshift
The cores of active galactic nuclei (AGN) harbor some of the most extreme conditions of matter and energy in the Universe. One of the major goals of high-energy astrophysics is to probe these extreme environments in the vicinity of supermassive black holes, which are intimately linked to the mechanisms that produce the continuum emission in AGN. X-ray studies seek to understand the physics resp...
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We apply a simple model, tested on local ULIRGs, to disentangle the active galactic nucleus (AGN) and starburst contributions in submillimiter and 24 μm-selected ULIRGs observed with the Spitzer-IRS spectrometer. We quantitatively estimate the average AGN contribution to the stacked 6−8 μm rest-frame spectra of these sources in different luminosity and redshift ranges, and, under the assumption...
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ASTRONOMY AND ASTROPHYSICS AGN and starbursts at high redshift: High resolution EVN radio observations of the Hubble Deep Field. Abstract. We present deep, wide-field European VLBI Network (EVN) 1.6 GHz observations of the Hubble Deep Field (HDF) region with a resolution of 0.025 arcseconds. Above the 210 µJy/beam (5σ) detection level, the EVN clearly detects two radio sources in a field that e...
متن کاملFirst Measurement of a Rapid Increase in the Agn Fraction in High-redshift Clusters of Galaxies
We present the first measurement of the AGN fraction in high-redshift clusters of galaxies (z ∼ 0.6) with spectroscopy of one cluster and archival data for three additional clusters. We identify 8 AGN in all four of these clusters from the Chandra data, which are sensitive to AGN with hard X-ray (2-10keV) luminosity LX ,H > 1043 erg s−1 in host galaxies more luminous than a rest frame MR < −20 ...
متن کاملOn the faint end of the high redshift AGN luminosity function
Using the results of recent optical surveys we conclude that the non-detection of quasars down to faint magnitudes implies a significant flattening of the high redshift (z ∼ 6) optical active galactic nuclei (AGN) luminosity function for M1450 > −26.7. We find that all the data are consistent with a faint-end slope for the optical AGN luminosity function of β = −2.2 and β = −2.8, at the 90% and...
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ژورنال
عنوان ژورنال: Advances in Astronomy
سال: 2012
ISSN: 1687-7969,1687-7977
DOI: 10.1155/2012/271502