X-RAY SPECTRAL VARIABILITY IN NGC-7469

We present analyses of two Ginga observations and two observations fro m the ROSAT database of NGC 7469, focusing on the spectral variability observed on timescales of days and longer. During the 3 day 1988 Giny a observation, the hardness ratio (8-21 keV/3.4-5.7 keV) increased sig nificantly as the total flux decreased by 30%. As the spectrum is well fit by the reflection model and since the spectral variability domina tes the higher energy band, this could be explained by either a variat ion in the power-law index or in the effective covering fraction of th e reflecting material. This ambiguity is inherent in reflection modeli ng of Ginga spectra from moderate flux Seyfert 1 galaxies. Assuming th at the power-law index did not change, we find that the reflected flux is consistent with being constant, suggesting that much of the reflec ting material may be located more than 3 light-days from the continuum source with the molecular torus being a plausible site. This scenario is also supported by the report of a narrow rather than broad iron K alpha line in the ASCA data by Guainazzi et al. NGC 7469 was faint dur ing the 1989 Ginga observation, but variability was observed with doub ling timescale of 5 hr, and the spectrum was harder. A reflection comp onent could not be constrained, and the change in the spectrum could b e explained by an increase in neutral absorption. The brighter of two ROSAT spectra was significantly softer, and in both spectra there was evidence of spectral complexity, as has been previously reported by Tu rner, George, & Mushotzky and Brandt et al. The spectrum could be fit by a variety of two-component models, including a warm absorber model, an ionized disk model, and a thermal model with single-component blac kbody spectrum, but joint fitting of the 1988 average Ginya spectrum a nd the nonsimultaneous ROSAT spectra favored thermal models, as other models required an anomalously high reflection ratio. This model is su pported by the observation of a soft excess component and the lack of ionized absorption edges in the ASCA spectrum by Guainazzi et al. The long-term spectral variability could be explained by relative variabil ity between the power-law and soft excess component normalizations, pe rhaps implying that hard X-ray reprocessing in thermal material does n ot dominate on long timescales.