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The Surprising Absence of Absorption in the Far-ultraviolet Spectrum of Mrk 231Mrk 231, the nearest (z = 0.0422) quasar, hosts both a galactic-scale wind and a nuclear-scale iron low-ionization broad absorption line (FeLoBAL) outflow. We recently obtained a far-ultraviolet (FUV) spectrum of this object covering approx. 1150-1470A with the Cosmic Origins Spectrograph on board the Hubble Space Telescope. This spectrum is highly peculiar, highlighted by the presence of faint (< or approx.2% of predictions based on H(alpha)), broad (> or approx.10,000 km/s at the base), and highly blueshifted (centroid at approx. 3500 km/s) Ly(aplpha) emission. The FUV continuum emission is slightly declining at shorter wavelengths (consistent with F(sub lambda) Alpha Lambda(sup 1.7)) and does not show the presence of any obvious photospheric or wind stellar features. Surprisingly, the FUV spectrum also does not show any unambiguous broad absorption features. It thus appears to be dominated by the AGN, rather than hot stars, and virtually unfiltered by the dusty FeLoBAL screen. The observed Ly(alpha) emission is best explained if it is produced in the outflowing BAL cloud system, while the Balmer lines arise primarily from the standard broad emission line region seen through the dusty (Av approx. 7 mag) broad absorption line region. Two possible geometric models are discussed in the context of these new results.
Document ID
Document Type
Reprint (Version printed in journal)
Veilleux, S.
(Maryland Univ. College Park, MD, United States)
Trippe, M.
(Maryland Univ. College Park, MD, United States)
Hamann, F.
(Florida Univ. Gainesville, FL, United States)
Rupke, D. S. N.
(Rhodes Coll. Memphis, TN, United States)
Tripp, T. M.
(Massachusetts Univ. Amherst, MA, United States)
Netzer, H.
(Tel-Aviv Univ. Israel)
Lutz, D.
(Max-Planck-Inst. fuer Extraterrestrische Physik Garching, Germany)
Sembach, K. R.
(Space Telescope Science Inst. Baltimore, MD, United States)
Krug, H.
(Maryland Univ. College Park, MD, United States)
Teng, Stacy H.
(Oak Ridge Associated Universities Greenbelt, MD, United States)
Genzel, R.
(Max-Planck-Inst. fuer Extraterrestrische Physik Garching, Germany)
Maiolino, R.
(Cambridge Univ. United Kingdom)
Sturm, E.
(Max-Planck-Inst. fuer Extraterrestrische Physik Garching, Germany)
Tacconi, L.
(Max-Planck-Inst. fuer Extraterrestrische Physik Garching, Germany)
Date Acquired
September 7, 2013
Publication Date
January 21, 2013
Publication Information
Publication: The Astrophysical Journal
Volume: 764
Issue: 1
Subject Category
Report/Patent Number
Funding Number(s)
Distribution Limits
Public Use Permitted.
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