Skip to main content

Research Repository

Advanced Search

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.

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


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


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.


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.

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
Keywords Black hole physics, Quasars: individual (PDS 456), X-rays: galaxies.


Published Journal Article (676 Kb)

Copyright Statement
© 2014. The American Astronomical Society. All rights reserved.

You might also like

Downloadable Citations