Variability of the High-velocity Outflow in the Quasar PDS 456

Reeves, J.N.; Braito, V.; Gofford, J.; Sim, S.A.; Behar, E.; Costa, M.; Kaspi, S.; Matzeu, G.; Miller, L.; O'Brien, P.; Turner, T.J.; Ward, M.

doi:10.1088/0004-637x/780/1/45

Variability of the High-velocity Outflow in the Quasar PDS 456

Reeves, J.N.; Braito, V.; Gofford, J.; Sim, S.A.; Behar, E.; Costa, M.; Kaspi, S.; Matzeu, G.; Miller, L.; O'Brien, P.; Turner, T.J.; Ward, M.

Authors

J.N. Reeves

V. Braito

J. Gofford

S.A. Sim

E. Behar

M. Costa

S. Kaspi

G. Matzeu

L. Miller

P. O'Brien

T.J. Turner

Professor Martin Ward martin.ward@durham.ac.uk
External Examiner (PGR)

Abstract

We present a comparison of two Suzaku X-ray observations of the nearby (z = 0.184), luminous (L bol ~ 1047 erg s–1) type I quasar, PDS 456. A new 125 ks Suzaku observation in 2011 caught the quasar during a period of low X-ray flux and with a hard X-ray spectrum, in contrast with a previous 190 ks Suzaku observation in 2007 when the quasar appeared brighter and had a steep (Γ > 2) X-ray spectrum. The 2011 X-ray spectrum contains a pronounced trough near 9 keV in the quasar rest frame, which can be modeled with blueshifted iron K-shell absorption, most likely from the He- and H-like transitions of iron. The absorption trough is observed at a similar rest-frame energy as in the earlier 2007 observation, which appears to confirm the existence of a persistent high-velocity wind in PDS 456, at an outflow velocity of 0.25-0.30c. The spectral variability between 2007 and 2011 can be accounted for by variations in a partial covering absorber, increasing in covering fraction from the brighter 2007 observation to the hard and faint 2011 observation. Overall, the low-flux 2011 observation can be explained if PDS 456 is observed at relatively low inclination angles through a Compton-thick wind, originating from the accretion disk, which significantly attenuates the X-ray flux from the quasar.

Citation

Reeves, J., Braito, V., Gofford, J., Sim, S., Behar, E., Costa, M., …Ward, M. (2014). Variability of the High-velocity Outflow in the Quasar PDS 456. Astrophysical Journal, 780(1), Article 45. https://doi.org/10.1088/0004-637x/780/1/45

Journal Article Type	Article
Publication Date	Jan 1, 2014
Deposit Date	May 29, 2014
Publicly Available Date	Jun 23, 2014
Journal	Astrophysical Journal
Print ISSN	0004-637X
Electronic ISSN	1538-4357
Publisher	American Astronomical Society
Peer Reviewed	Peer Reviewed
Volume	780
Issue	1
Article Number	45
DOI	https://doi.org/10.1088/0004-637x/780/1/45
Keywords	Black hole physics, Quasars: individual (PDS 456), X-rays: galaxies.