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Posts: 131433
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SDSS J093620.52+004649.2
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Case of missing quasar gas clouds now solved

The case of the missing quasar gas clouds has been solved by a worldwide research team led by Penn State astronomers Nurten Filiz Ak and Niel Brandt. The discovery was announced Oct. 1 in a paper published in The Astrophysical Journal, which describes 19 distant quasars whose giant clouds of gas seem to have disappeared in just a few years.
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Mini-BAL Quasar
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Title: X-Ray Insights Into the Physics of Mini-BAL Quasar Outflows
Authors: Robert R. Gibson, W. N. Brandt, S. C. Gallagher, Donald P. Schneider

We examine the UV and X-ray properties of 256 radio-quiet SDSS quasars (QSOs) observed in X-rays with Chandra and/or XMM-Newton in order to study the relationship between QSOs with broad CIV absorption lines (BALs; width >2000 km/s) and those with CIV mini-BALs (here defined to have widths of 1000--2000 km/s). Our sample includes 42 BAL and 48 mini-BAL QSOs. The relative X-ray brightness and hard spectral slopes of the mini-BAL population are, on average, intermediate between those of BAL and non-BAL QSOs, as might be expected if narrower and broader absorption line outflows are physically related. However, a significant population of mini-BALs has outflow velocities higher than would be expected for BAL QSOs of the same relative X-ray brightness. Consistently strong X-ray absorption is apparently not required to accelerate at least some mini-BALs to high outflow velocities. Assuming the mini-BAL features are correctly attributed to intrinsic CIV absorption, we suggest that their observed properties may be explained if mini-BALs are "seeds" which can be accelerated to form BALs when sufficient X-ray shielding is present.
We also examine several QSOs with broad CIV absorption that have been recently reported to be unusually X-ray bright. Such cases are frequently mini-BAL QSOs, which as a population are generally brighter in X-rays than BAL QSOs. Pointed XMM-Newton observations also suggest that these sources (or unresolved neighbours) may have been previously observed in a high flux state.

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Posts: 131433
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BAL quasars
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XMM-Newton has been surprised by a rare type of galaxy, from which it has detected a higher number of X-rays than thought possible. The observation gives new insight into the powerful processes shaping galaxies during their formation and evolution.
 Scientists working with XMM-Newton were looking into the furthest reaches of the universe, at celestial objects called quasars. These are vast cosmic engines that pump energy into their surroundings. It is thought an enormous black hole drives each quasar.

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