University of Hertfordshire

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From the same journal

By the same authors

Discovery of an Ultraviolet Counterpart to an Ultra-Fast X-ray Outflow in the Quasar PG1211+143

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  • Gerard A. Kriss
  • Julia C. Lee
  • Ashkbiz Danehkar
  • Michael A. Nowak
  • Taotao Fang
  • Martin J. Hardcastle
  • Joseph Neilsen
  • Andrew Young
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Original languageEnglish
Article number166
JournalThe Astrophysical Journal
Publication statusPublished - 2 Feb 2018


We observed the quasar PG 1211+143 using the Cosmic Origins Spectrograph on the Hubble Space Telescope in 2015 April as part of a joint campaign with the Chandra X-ray Observatory and the Jansky Very Large Array. Our ultraviolet spectra cover the wavelength range 912-2100 Å. We find a broad absorption feature () at an observed wavelength of 1240 Å. Interpreting this as H i Lyα, in the rest frame of PG 1211+143 (z = 0.0809), this corresponds to an outflow velocity of -16,980 (outflow redshift ), matching the moderate ionization X-ray absorption system detected in our Chandra observation and reported previously by Pounds et al. With a minimum H i column density of , and no absorption in other UV resonance lines, this Lyα absorber is consistent with arising in the same ultrafast outflow as the X-ray absorbing gas. The Lyα feature is weak or absent in archival ultraviolet spectra of PG 1211+143, strongly suggesting that this absorption is transient, and intrinsic to PG 1211+143. Such a simultaneous detection in two independent wavebands for the first time gives strong confirmation of the reality of an ultrafast outflow in an active galactic nucleus.


This is an author-created, un-copyedited version of an article published in The Astrophysical Journal. The Version of Record is available online at


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