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Reddening, Emission-Line, and Intrinsic Absorption Properties in the Narrow-Line Seyfert 1 Galaxy Akn 564

D. M. Crenshaw·S. B. Kraemer·T. J. Turner·S. Collier·B. M. Peterson·W. N. Brandt·J. Clavel·I. M. George·K. Horne·G. A. Kriss·S. Mathur·H. Netzer·R. W. Pogge·K. A. Pounds·P. Romano·O. Shemmer·W. Wamsteker
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Abstract

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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D. M. Crenshaw, S. B. Kraemer, T. J. Turner, S. Collier, B. M. Peterson, W. N. Brandt, J. Clavel, I. M. George, K. Horne, G. A. Kriss, S. Mathur, H. Netzer, R. W. Pogge, K. A. Pounds, P. Romano, O. Shemmer, W. Wamsteker. 2001-10-12. Reddening, Emission-Line, and Intrinsic Absorption Properties in the Narrow-Line Seyfert 1 Galaxy Akn 564. https://doi.org/10.1086/338058

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