Reddening, Emission-Line and Intrinsic Absorption Properties in the Narrow-Line Seyfert 1 Galaxy Akn 564.
| Authors:
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Crenshaw, D.M.,
Kraemer, S.,
Turner, T.J.,
Collier, S.,
Peterson, B.M.,
Brandt, W.N.,
Clavel, J.
George, I.M.
Horne, K.,
Kriss, G.A.,
Mathur, S.,
Netzer, H.
Pogge, R.W., Pounds, K.A.,
Romano, P.,
Shemmer, O.,
Wamsteker, W.
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| Affiltns:
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incomplete
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| Journal:
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ApJ
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| Publn Date:
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in press
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Summary
We use Hubble Space Telescope UV and optical spectra of the narrow-line Seyfert 1 (NLS1) galaxy Akn 564 to investigate its
internal reddening and properties of its emission-line and intrinsic UV absorption gas. We find that the extinction curve of Akn
564, derived from a comparison of its UV/optical continuum to that of an unreddened NLS1, lacks a 2200 A bump and turns up
towards the UV at a longer wavelength (4000 A) than the standard Galactic, LMC, and SMC curves. However, it does not show
the extremely steep rise to 1200 A that characterizes the extinction curve of the Seyfert 1 galaxy NGC 3227. The emission-lines
and continuum experience the same amount of reddening, indicating the presence of a dust screen that is external to the
narrow-line region (NLR). Echelle spectra from the Space Telescope Imaging Spectrograph show intrinsic UV absorption lines
due to Ly-alpha, N V, C IV, Si IV, and Si III, centered at a radial velocity of -190 km/s (relative to the host galaxy).
Photoionization models of the UV absorber indicate that it has a sufficient columnand is at a sufficient distance from the nucleus
(D > 95 pc) to be the source of the dust screen. Thus, Akn 564 contains a dusty ``lukewarm absorber'' similar to that seen in
NGC 3227.
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