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RE: High Luminosity Quasar PDS 456
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Title: Black hole feedback in the luminous quasar PDS 456
Author: E. Nardini, J. N. Reeves, J. Gofford, F. A. Harrison, G. Risaliti, V. Braito, M. T. Costa, G. A. Matzeu, D. J. Walton, E. Behar, S. E. Boggs, F. E. Christensen, W. W. Craig, C. J. Hailey, G. Matt, J. M. Miller, P. T. O'Brien, D. Stern, T. J. Turner, M. J. Ward

The evolution of galaxies is connected to the growth of supermassive black holes in their centers. During the quasar phase, a huge luminosity is released as matter falls onto the black hole, and radiation-driven winds can transfer most of this energy back to the host galaxy. Over five different epochs, we detected the signatures of a nearly spherical stream of highly ionized gas in the broadband X-ray spectra of the luminous quasar PDS 456. This persistent wind is expelled at relativistic speeds from the inner accretion disk, and its wide aperture suggests an effective coupling with the ambient gas. The outflow's kinetic power larger than 10^46 ergs per second is enough to provide the feedback required by models of black hole and host galaxy co-evolution.

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Black hole's blast stunts birth of stars

Winds blasted out by the giant black holes found at the centre of galaxies are strong enough to stunt the birth of new stars, astronomers have found.
By training two space telescopes on a supermassive black hole with the mass of a billion Suns, they measured the strength of its ferocious winds.

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PDS 456
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Title: Remarkable Spectral Variability of PDS 456
Authors: Ehud Behar, Shai Kaspi, James Reeves, T.J. Turner, Richard Mushotzky, Paul T. O'Brien

We report on the highest to date signal-to-noise-ratio X-ray spectrum of the luminous quasar PDS 456, as obtained during two XMM-Newton orbits in September 2007. The present spectrum is considerably different from several previous X-ray spectra recorded for PDS 456 since 1998. The ultra-high-velocity outflow seen as recently as February 2007 is not detected in absorption. Conversely, a significant reflection component is detected. The reflection model suggests the reflecting medium may be outflowing at a velocity v/c = -0.06 0.02. The present spectrum is analysed in the context of the previous ones in an attempt to understand all spectra within the framework of a single model. We examine whether an outflow with variable partial covering of the X-ray source along the line of sight that also reflects the source from other lines of sight can explain the dramatic variations in the broad-band spectral curvature of PDS 456. It is established that absorption plays a major role in shaping the spectrum of other epochs, while the 2007 XMM-Newton spectrum is dominated by reflection, and the coverage of the source by the putative outflow is small (< 20%).

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High Luminosity Quasar PDS 456
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Title: A Compton-thick Wind in the High Luminosity Quasar, PDS 456
Authors: J.N. Reeves, P.T. O'Brien, V. Braito, E. Behar, L. Miller, T.J. Turner, A.C. Fabian, S. Kaspi, R. Mushotzky, M. Ward

PDS 456 is a nearby (z=0.184), luminous (L_bol ~10^47 erg/s) type I quasar. A deep 190 ks Suzaku observation in February 2007 revealed the complex, broad band X-ray spectrum of PDS 456. The Suzaku spectrum exhibits highly statistically significant absorption features near 9 keV in the quasar rest--frame. We show that the most plausible origin of the absorption is from blue-shifted resonance (1s-2p) transitions of hydrogen-like iron (at 6.97 keV in the rest frame). This indicates that a highly ionised outflow may be present moving at near relativistic velocities (~0.25c). A possible hard X-ray excess is detected above 15 keV with HXD (at 99.8% confidence), which may arise from high column density gas (Nh>10^24cm^-2) partially covering the X-ray emission, or through strong Compton reflection. Here we propose that the iron K-shell absorption in PDS 456 is associated with a thick, possibly clumpy outflow, covering about 20% of 4\pi steradian solid angle. The outflow is likely launched from the inner accretion disk, within 15-100 gravitational radii of the black hole. The kinetic power of the outflow may be similar to the bolometric luminosity of PDS 456. Such a powerful wind could have a significant effect on the co-evolution of the host galaxy and its supermassive black hole, through feedback.

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