Multiwavelength Monitoring of the Narrow-Line Seyfert 1 Galaxy Akn 564. II. Ultraviolet Continuum and Emission-line Variability

S. Collier; D. M. Crenshaw; B. M. Peterson; W. N. Brandt; J. Clavel; R. Edelson; I. M. George; K. Horne; G. A. Kriss; S. Mathur; H. Netzer; P. T. O'Brien; R. W. Pogge; K. A. Pounds; P. Romano; O. Shemmer; T. J. Turner; W. Wamsteker

doi:10.1086/323234

arXiv · astro-ph/0107059

Multiwavelength Monitoring of the Narrow-Line Seyfert 1 Galaxy Akn 564. II. Ultraviolet Continuum and Emission-line Variability

S. Collier·D. M. Crenshaw·B. M. Peterson·W. N. Brandt·J. Clavel·R. Edelson·I. M. George·K. Horne·G. A. Kriss·S. Mathur·H. Netzer·P. T. O'Brien·R. W. Pogge·K. A. Pounds·P. Romano·O. Shemmer·T. J. Turner·W. Wamsteker

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Abstract

We present results of an intensive two-month campaign of approximately daily spectrophotometric monitoring of the narrow-line Seyfert 1 galaxy Akn 564 with HST. The fractional variability amplitude of the continuum variations between 1365-3000 A is ~6%, about a factor 3 less than that found in typical Seyfert 1 galaxies over a similar period of time. However, large amplitude, short time-scale flaring behavior is evident, with trough-to-peak flux changes of about 18% in approximately 3 days. We present evidence for wavelength-dependent continuum time delays, with the variations at 3000 A lagging behind those at 1365 A by about 1 day. These delays may be interpreted as evidence for a stratified continuum reprocessing region, possibly an accretion-disk structure. The Lyman-alpha 1216 emission-line exhibits flux variations of about 1% amplitude.

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S. Collier, D. M. Crenshaw, B. M. Peterson, W. N. Brandt, J. Clavel, R. Edelson, I. M. George, K. Horne, G. A. Kriss, S. Mathur, H. Netzer, P. T. O'Brien, R. W. Pogge, K. A. Pounds, P. Romano, O. Shemmer, T. J. Turner, W. Wamsteker. 2001-07-03. Multiwavelength Monitoring of the Narrow-Line Seyfert 1 Galaxy Akn 564. II. Ultraviolet Continuum and Emission-line Variability. https://doi.org/10.1086/323234

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