Reeves, JN, Braito, V, Nardini, E, Hamann, F, Chartas, G, Lobban, AP ORCID: 0000-0002-6433-1357, Brien, PTO and Turner, TJ (2018) Resolving the X-Ray Obscuration in a Low-flux Observation of the Quasar PDS 456. Astrophysical Journal, 867 (1). 38 -38. ISSN 0004-637X

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Abstract

Simultaneous XMM-Newton , NuSTAR , and HST observations, performed in 2017 March, of the nearby ( z = 0.184) luminous quasar PDS 456 are presented. PDS 456 had a low X-ray flux compared to past observations, where the first of the two new XMM-Newton observations occurred during a pronounced dip in the X-ray light curve. The broadband X-ray spectrum is highly absorbed, attenuated by a soft X-ray absorber of column density N H = 6 × 10 22 cm −2 . An increase in obscuration occurs during the dip, which may be due to an X-ray eclipse. In addition, the persistent, fast Fe K outflow is present, with velocity components of −0.25 c and −0.4 c . The soft absorber is less ionized ( ##IMG## [http://ej.iop.org/images/0004-637X/867/1/38/apjaae30cieqn1.gif] $\mathrmlogξ =3$ ) compared to the iron K outflow ( ##IMG## [http://ej.iop.org/images/0004-637X/867/1/38/apjaae30cieqn2.gif] $\mathrmlogξ =5$ ) and is outflowing with a velocity of approximately −0.2 c . A soft X-ray excess is present below 1 keV against the highly absorbed continuum and can be attributed to the re-emission from a wide-angle wind. The complex X-ray absorption present in PDS 456 suggests that the wind is inhomogeneous, whereby the soft X-ray absorber originates from denser clumps or filaments that may form farther out along the outflow. In contrast to the X-ray observations, the simultaneous UV spectrum of PDS 456 is largely unabsorbed, where only a very weak broad absorption trough is present blueward of Ly α , compared to a past observation in 2000 when the trough was significantly stronger. The relative weakness of the UV absorption may be due to the soft X-ray absorber being too highly ionized and almost transparent in the UV band.

Item Type: Article
Additional Information: © 2018 The American Astronomical Society. All rights reserved. This is the final published version of the article (version of record). It first appeared online via American Astronomical Society and IOP at http://doi.org/10.3847/1538-4357/aae30c - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: black hole physics, galaxies, active, quasars, individual (PDS 456), X-rays, galaxies
Depositing User: Symplectic
Date Deposited: 06 Nov 2018 09:38
Last Modified: 14 Nov 2018 09:21
URI: http://eprints.keele.ac.uk/id/eprint/5480

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