1. Min-zhi Kong Physical Parameters Related to AGN Variability ---- especially for NGC 5548

2. outline parameters of AGN variability Observations and theoretical models for NGC 5548 Fitting the correlation between the variation of the optical spectral index and the continuum luminosity for NGC 5548 summary

3.  Flux density variation of continuum or lines I AGN variability parameters (Ulrich et al. 1997)(Kollatschny & Dietrich 1996) NGC 4151 NGC 5548

4.  continuum and line shape (Ulrich et al. 1997)  Correlations (Shapovalova et al. 2004) High state Low state

5.  Time delay between variations at different continuum or lines  Variation time scale (peterson et al. 2002)

6. Ⅱ Introduction for NGC5548 Observation for NGC 5548 in radio, infrared, UV, optical, X-ray,γ-ray The flux of the continuum and line are variable, correlated different time-delay existed Theoretical models

7.  X-ray reprocessing mode (Mushotzky Done & Pounds 1993; Utterly et al. 2003;Chiang et al. 2002, 2003; Czerny et al. 1999;Molendi et al. 1992) (Utterly et al. 2003)

8.  A model from the spectral decomposition of the variable multi-wavelength continuum (Magdziarz et al. 1998) 1) A cool multitemperature blackbody (dot-shot- dashed) 2) An EUV/soft x-ray component (short- dashed) 3) A hard thermal comptonized component (long- dashed)

9.  The spectral index increasing with the monochromatic luminosity result from the radiation temperature changes of an emitting blackbody (Trevese et al. 2001; Kawaguchi et al. 1998) (Trevese & Vagnetti 2001)

10. Ⅲ correlation of α opt, L 5100 and fitting Continuum luminosity at 5100Å http://www.astronomy.ohio- state.edu/~agnwatch http://www.astronomy.ohio- state.edu/~agnwatch Host galaxy contributions : 3.4*10 -15 ergs -1 Å -1 (Romainishin et al. 1995) Galaxy extinction : 0.020 Redshift correction : 0.017 α opt Optical spectral index α opt Fit in line free regions 3700~3715Å, 3740~3800Å, 4041~4043Å, 4150~4250Å, 5550~5850Å, 6000~6290Å, 6400~6450 No considering host galaxy effect Wavelength range : ≥ 4000Å and ≥ 6000Å

11. 431 data points The coefficient is –0.8 The optical continuum slope becomes flatter when it becomes more bright The light curves for λL λ and α opt

12. Accretion disk model The five free parameters M BH =12.3×10 7 M sun (Kaspi et al. 2000) i=45 0 (Chiang et al. 2003; Wu & Han 2001) Rout ~ 10 5 Rs The possible mechanisms, the accretion rate, the inner edge of the disk A co-variable mode

13. Results

14. A = 12.5 The accretion rate ranges: 0.05~0.16 the inner radius of the accretion disk changes: 133.9~55.5R s

15. conclusions can fit the correlation between the optical index and continuum luminosity well The accretion rate ranges: 0.05~0.16; the inner radius of the accretion disk changes: 133.9~55.5R s Consistent with the following works: Support a physical phenomenon : for NGC55448, ADAF + SSD

16. Thanks