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تسجيل مستخدم جديدThe brightest ULIRG:watching the birth of a quasar
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The extreme ULIRG F00183-7111 has recently been found to have a radio-loud AGN with jets in its centre, representing an extreme example of the class of radio-loud AGNs buried within dusty star-forming galaxies. This source appears to be a rare example of a ULIRG glimpsed in the (presumably) brief period as it changes from quasar mode to radio mode activity. Such transition stages probably account for many of the high-redshift radio-galaxies and extreme high-redshift ULIRGs, and so this object at the relatively low redshift of 0.328 offers a rare opportunity to study this class of objects in detail. We have also detected the CO signal from this galaxy with the ATCA, and here describe the implications of this detection for future ULIRG studies.
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F00183-7111 is one of the most extreme Ultra-Luminous Infrared Galaxies known. Here we present a VLBI image which shows that F00183-7111 is powered by a combination of a radio-loud Active Galactic Nucleus surrounded by vigorous starburst activity. Al
though already radio-loud, the quasar jets are only 1.7 kpc long, boring through the dense gas and starburst activity that confine them. We appear to be witnessing this remarkable source in the brief transition period between merging starburst and radio-loud quasar-mode accretion.
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> 3*10^44 erg/s) in which AGN-jetted outflows are creating and sustaining clear Xray cavities. Our sample covers the redshift range 0 < z < 0.6 and reveals strong evolution in the nuclear X-ray luminosities, such that the black holes in these systems have become on average at least 10 times fainter over the last 5 Gyrs. Mindful of potential selection effects, we propose two possible scenarios to explain our results: 1) either that the AGNs in BCGs with X-ray cavities are steadily becoming fainter, or more likely, 2) that the fraction of these BCGs with radiatively efficient nuclei is decreasing with time from roughly 60 per cent at z=0.6 to 30 per cent at z=0.1. Based on this strong evolution, we predict that a significant fraction of BCGs in z=1 clusters may host quasars at their centres, potentially complicating the search for such clusters at high redshift. In analogy with black-hole binaries and based on the observed Eddington ratios of our sources, we further propose that the evolving AGN population in BCGs with X-ray cavities may be transiting from a canonical low/hard state, analogous to that of X-ray binaries, to a quiescent state over the last 5 Gyrs.
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