Iron K emission line time-lags in MCG-6-30-15 Original Research Article

We investigate spectral variations dependent on short timescale variations in the Seyfert galaxy MCG-6-30-15 using data obtained with ASCA in 1994. Spectral hardening of the continuum spectrum during a large flare lasting for ∼ 5 × 104 sec was observed. Such spectral hardening is commonly observed in stellar black hole candidates. This and other similarities in X-rays between these objects suggest their time variations have the same origin. We have also found that the narrow iron Kα line is more prominent in the decay phase of the flare than in the rise phase. This implies time lags of the narrow iron-line component behind the continuum component, which indicate that the narrow iron Kα line is present in the outer region (∼ 1000 rs) of the accretion disk.