Multiwavelength Monitoring of the Narrow-Line Seyfert 1 Galaxy Akn 564.
II. Ultraviolet Continuum and Emission-line Variability
| Authors:
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Collier, S.J.,
Crenshaw, D.M.,
Peterson, B.M.,
Brandt, W.N.,
Clavel, J.,
Edelson, R.,
George, I.M.,
Horne, K.,
Kriss, G.A.,
Mathur, S.,
Netzer, H.,
O'Brien, P.T., Pogge, R.W.,
Pounds, K.A.,
Romano, P.,
Shemmer, O.,
Turner, T.J.,
Wamsteker, W.,
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| Affiltns:
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incomplete
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| Journal:
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ApJ, 561, 146
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| Publn Date:
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Summary
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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