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arXiv · 1712.08850

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

Gerard A. Kriss·Julia C. Lee·Ashkbiz Danehkar·Michael A. Nowak·Taotao Fang·Martin J. Hardcastle·Joseph Neilsen·Andrew Young
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Abstract

We observed the quasar PG1211+143 using the Cosmic Origins Spectrograph on the Hubble Space Telescope in April 2015 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 A. We find a broad absorption feature (~1080 km/s) at an observed wavelength of 1240 A. Interpreting this as HI Ly alpha, in the rest frame of PG1211+143 (z=0.0809), this corresponds to an outflow velocity of -16,980 km/s (outflow redshift z_out ~ -0.0551), matching the moderate ionization X-ray absorption system detected in our Chandra observation and reported previously by Pounds et al. (2016). With a minimum HI column density of log N_HI > 14.5, and no absorption in other UV resonance lines, this Ly alpha absorber is consistent with arising in the same ultra-fast outflow as the X-ray absorbing gas. The Ly alpha feature is weak or absent in archival ultraviolet spectra of PG1211+143, strongly suggesting that this absorption is transient, and intrinsic to PG1211+143. Such a simultaneous detection in two independent wavebands for the first time gives strong confirmation of the reality of an ultra-fast outflow in an active galactic nucleus.

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Gerard A. Kriss, Julia C. Lee, Ashkbiz Danehkar, Michael A. Nowak, Taotao Fang, Martin J. Hardcastle, Joseph Neilsen, Andrew Young. 2017-12-23. Discovery of an Ultraviolet Counterpart to an Ultra-Fast X-ray Outflow in the Quasar PG1211+143. https://doi.org/10.3847/1538-4357%2Faaa42b

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