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An ultrafast inflow in the luminous Seyfert PG1211+143

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journal contribution
posted on 12.07.2019, 14:59 by KA Pounds, C Nixon, A Lobban, AR King
Blueshifted absorption lines in the X-ray spectra of an active galactic nucleus (AGN) show that ultrafast outflows with typical velocities v ∼ 0.1c are a common feature of these luminous objects. Such powerful AGN winds offer an explanation of the observed M–σ relation linking the mass of the supermassive black hole and the velocity dispersion in the galaxy’s stellar bulge. An extended XMM–Newton study of the luminous Seyfert galaxy PG1211+143 recently revealed a variable multivelocity wind. Here we report the detection of a short-lived, ultrafast inflow during the same observation. Previous reports of inflows used single absorption lines with uncertain identifications, but this new result identifies an array of resonance absorption lines of highly ionized Fe, Ca, Ar, S, and Si, sharing a common redshift when compared with a grid of realistic photoionization spectra. The redshifted absorption arises in a column of highly ionized matter close to the black hole, with a line-of-sight velocity, v ∼ 0.3c, inconsistent with the standard picture of a plane circular accretion disc. This may represent the first direct evidence for chaotic accretion in an AGN, where accretion discs are generally misaligned to the black hole spin. For sufficient inclinations, the Lense–Thirring effect can break the discs into discrete rings, which then precess, collide, and shock, causing near free-fall of gas towards the black hole. The observed accretion rate for the reported infall is comparable to the hard X-ray luminosity in PG1211+143, suggesting that direct infall may be a significant contributor to inner disc accretion.

Funding

CN holds an Ernest Rutherford Fellowship (ST/M005917/1) and AL is supported by a consolidated grant to Keele, both funded by the UK Science and Technology Facilities Council.

History

Citation

Monthly Notices of the Royal Astronomical Society, 2018, 481 (2), pp. 1832-1838

Author affiliation

/Organisation/COLLEGE OF SCIENCE AND ENGINEERING/Department of Physics and Astronomy

Version

VoR (Version of Record)

Published in

Monthly Notices of the Royal Astronomical Society

Publisher

Oxford University Press (OUP), Royal Astronomical Society

issn

0035-8711

eissn

1365-2966

Acceptance date

28/08/2018

Copyright date

2018

Available date

12/07/2019

Publisher version

https://academic.oup.com/mnras/article/481/2/1832/5090165

Language

en