The Ultra-Fast Outflow of the Quasar PG 1211+143 as Viewed by Time-Averaged Chandra Grating Spectroscopy

Ashkbiz Danehkar, Michael A. Nowak, Julia C. Lee, Gerard A. Kriss, Andrew J. Young, Martin J. Hardcastle, Susmita Chakravorty, Taotao Fang, Joseph Neilsen, Farid Rahoui, Randall K. Smith

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We present a detailed X-ray spectral study of the quasar PG 1211+143 based on Chandra High Energy Transmission Grating Spectrometer (HETGS) observations collected in a multi-wavelength campaign with UV data using the Hubble Space Telescope Cosmic Origins Spectrograph (HST-COS) and radio bands using the Jansky Very Large Array (VLA). We constructed a multi-wavelength ionizing spectral energy distribution using these observations and archival infrared data to create xstar photoionization models specific to the PG 1211+143 flux behavior during the epoch of our observations. Our analysis of the Chandra-HETGS spectra yields complex absorption lines from H-like and He-like ions of Ne, Mg, and Si, which confirm the presence of an ultra-fast outflow (UFO) with a velocity of approximately -17,300 km s -1 (outflow redshift z out ∼ -0.0561) in the rest frame of PG 1211+143. This absorber is well described by an ionization parameter and column density. This corresponds to a stable region of the absorber's thermal stability curve, and furthermore its implied neutral hydrogen column is broadly consistent with a broad Lyα absorption line at a mean outflow velocity of approximately -16,980 km s -1 detected by our HST-COS observations. Our findings represent the first simultaneous detection of a UFO in both X-ray and UV observations. Our VLA observations provide evidence for an active jet in PG 1211+143, which may be connected to the X-ray and UV outflows; this possibility can be evaluated using very-long-baseline interferometric observations.

Original languageEnglish
Article number165
JournalThe Astrophysical Journal
Issue number2
Publication statusPublished - 2 Feb 2018


  • X-rays: galaxies
  • galaxies: Seyfert
  • galaxies: active
  • quasars: absorption lines
  • quasars: individual (PG 1211+143)


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