Reeves, JN and Braito, V and Nardini, E and Behar, E and O'Brien, P and Tombesi, F and 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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Abstract

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 http://dx.doi.org/10.3847/0004-637x/824/1/20 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
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Depositing User: Symplectic
Date Deposited: 09 Dec 2016 12:19
Last Modified: 14 Nov 2017 15:34
URI: http://eprints.keele.ac.uk/id/eprint/2588

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