Reeves, JN, Braito, V, Nardini, E, Behar, E, O'Brien, P, Tombesi, F, Turner, TJ and Costa, M (2016) Discovery of Broad Soft X-ray Absorption Lines from the Quasar Wind in PDS 456. Astrophysical Journal, 824 (1). ISSN 0004-637X

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High resolution soft X-ray spectroscopy of the prototype accretion disk wind quasar, PDS 456, is presented. Here, the XMM-Newton RGS spectra are analyzed from the large 2013-2014 XMM-Newton campaign, consisting of 5 observations of approximately 100 ks in length. During the last observation (hereafter OBS. E), the quasar is at a minimum flux level and broad absorption line profiles are revealed in the soft X-ray band, with typical velocity widths of $\sigma_{\rm v}\sim 10,000$ km s$^{-1}$. During a period of higher flux in the 3rd and 4th observations (OBS. C and D, respectively), a very broad absorption trough is also present above 1 keV. From fitting the absorption lines with models of photoionized absorption spectra, the inferred outflow velocities lie in the range $\sim 0.1-0.2c$. The absorption lines likely originate from He and H-like neon and L-shell iron at these energies. Comparison with earlier archival data of PDS 456 also reveals similar absorption structure near 1 keV in a 40 ks observation in 2001, and generally the absorption lines appear most apparent when the spectrum is more absorbed overall. The presence of the soft X-ray broad absorption lines is also independently confirmed from an analysis of the XMM-Newton EPIC spectra below 2 keV. We suggest that the soft X-ray absorption profiles could be associated with a lower ionization and possibly clumpy phase of the accretion disk wind, where the latter is known to be present in this quasar from its well studied iron K absorption profile and where the wind velocity reaches a typical value of 0.3$c$.

Item Type: Article
Additional Information: © IOP Science; This is the accepted author manuscript (AAM). The final published version Reeves, J.N. et al., 2016. DISCOVERY OF BROAD SOFT X-RAY ABSORPTION LINES FROM THE QUASAR WIND IN PDS 456. The Astrophysical Journal, 824(1), p.20 is available online via IOP Science at Please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: black hole physics, quasars, individual (PDS 456), X-rays, galaxies
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Faculty of Natural Sciences > School of Physical and Geographical Sciences
Related URLs:
Depositing User: Symplectic
Date Deposited: 09 Dec 2016 12:19
Last Modified: 14 Nov 2017 15:34

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