Study of the spectral variability of MCG-6-30-15 during a remarkably strong flare period

The Seyfert 1 galaxy MCG-6-30-15 (z~=0.008, L_B~4×10⁴⁴ erg/s) was observed by XMM-Newton on 2000 June 11-12, for a total of 95 ks. The source shows high flux and spectral variability down to timescales of t ~300 s. This work presents the results of the time-resolved spectral analysis of the brightest flare (a factor of 2 variation in ~1000 s) which occurred during the observation. The analysis of such flare indicates: 1) a softening of the X-ray spectrum in phase with the flux, and 2) a soft-to-hard time lag of about ~ 600 s. A strong and complex Fe-Kαemission feature is detected ~ 3000 s after the flare. The same feature was not present before and during the flare. This may indicate that the Fe line was produced as a consequence of the flare. The present analysis allows the formulation of a different hypothesis for the physical mechanisms responsible for the X-ray emission.