Multiwavelength Monitoring of the Narrow-Line Seyfert 1 Galaxy Akn 564.
I. ASCA Observations and the Variability of the X-ray Spectral Components
| Authors:
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Turner, T.J.,
Romano, P.,
George, I.M.,
Edelson, R.,
Collier, S.J.,
Mathur, S.,
Peterson, B.M.,
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| Affiltns:
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incomplete
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| Journal:
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ApJ, 561, 131
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| Publn Date:
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Summary
We present a 35 day ASCA observation of the NLS1 Akn 564, which was part of a multiwavelength AGN Watch
monitoring
campaign. Akn 564 shows a photon index varying across the range 2.45--2.72.
The presence of the soft hump component below 1
keV, previously detected in ASCA data, is confirmed. Time-resolved spectroscopy with ~daily
sampling reveals a distinction in
the variability of the soft hump and power-law components over a timescale of weeks, with the
hump varying by a factor of 6
across the 35-day observation compared to a factor 4 in the power-law. Flux variations in the
power-law component are
measured down to a timescale of ~1000s and accompanying spectral variability suggests the soft
hump is not well-correlated
with the power-law on such short timescales. We detect Fe Ka and a blend of Fe Kb plus Ni Ka,
indicating an origin in highly
ionized gas. Variability measurements constrain the bulk of the Fe Ka to originate within a
light week of the nucleus. The large
EW of the emission lines may be due to high metallicity in NLS1s, supporting some evolutionary
models for AGN.
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