title: Broad line emission from iron K- and L-shell transitions in the active galaxy 1H 0707-495.
abstract: Since the 1995 discovery of the broad iron K-line emission from the Seyfert galaxy MCG-6-30-15 (ref. 1), broad iron K lines have been found in emission from 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 presence of both iron K and iron L emission in the spectrum of the narrow-line Seyfert 1 galaxy 1H 0707-495. The bright iron L emission has enabled us to detect a reverberation lag of about 30 s between the direct X-ray continuum and its reflection from matter falling into the black 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 1H 0707-495 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.
authors.affiliation: Institute of Astronomy, Madingley Road, Cambridge CB3 0HA, UK. acf@ast.cam.ac.uk
authors.forename: A C
authors.initials: AC
authors.lastname: Fabian
authors.forename: A
authors.initials: A
authors.lastname: Zoghbi
authors.forename: R R
authors.initials: RR
authors.lastname: Ross
authors.forename: P
authors.initials: P
authors.lastname: Uttley
authors.forename: L C
authors.initials: LC
authors.lastname: Gallo
authors.forename: W N
authors.initials: WN
authors.lastname: Brandt
authors.forename: A J
authors.initials: AJ
authors.lastname: Blustin
authors.forename: T
authors.initials: T
authors.lastname: Boller
authors.forename: M D
authors.initials: MD
authors.lastname: Caballero-Garcia
authors.forename: J
authors.initials: J
authors.lastname: Larsson
authors.forename: J M
authors.initials: JM
authors.lastname: Miller
authors.forename: G
authors.initials: G
authors.lastname: Miniutti
authors.forename: G
authors.initials: G
authors.lastname: Ponti
authors.forename: R C
authors.initials: RC
authors.lastname: Reis
authors.forename: C S
authors.initials: CS
authors.lastname: Reynolds
authors.forename: Y
authors.initials: Y
authors.lastname: Tanaka
authors.forename: A J
authors.initials: AJ
authors.lastname: Young
mesh_terms: D005118:Extraterrestrial Environment / Q000737:chemistry*; D007501:Iron / Q000032:analysis* / Q000737:chemistry
chemical_list: D007501:Iron