  Since the discovery of the first broad iron-K line in 1995 from the Seyfert
Galaxy MCG--6-30-15, broad iron-K lines have been found in several other
Seyfert galaxies, from accreting stellar mass black holes and even from
accreting neutron stars. The iron-K line is prominent in the reflection
spectrum created by the hard X-ray continuum irradiating dense accreting
matter. Relativistic distortion of the line makes it sensitive to the strong
gravity and spin of the black hole. The accompanying iron-L line emission
should be detectable when the iron abundance is high. Here we report the first
discovery of both iron-K and L emission, using XMM-Newton observations of the
Narrow-Line Seyfert 1 Galaxy 1H0707-495. The bright Fe-L emission has enabled
us, for the first time, to detect a reverberation lag of 30 s between the
direct X-ray continuum and its reflection from matter falling into the hole.
The observed reverberation timescale is comparable to the light-crossing time
of the innermost radii around a supermassive black hole. The combination of
spectral and timing data on 1H0707-495 provides strong evidence that we are
witnessing emission from matter within a gravitational radius, or a fraction of
a light-minute, from the event horizon of a rapidly-spinning, massive black
hole.

High Energy Astrophysical Phenomena;Cosmology and Nongalactic Astrophysics