We explore a disc origin for the highly blueshifted, variable absorption
lines seen in the X-ray spectrum of the narrow-line Seyfert 1 galaxy
IRAS 13224-3809. The blueshift corresponds to a velocity of ∼0.25c.
Such features in other active galactic nuclei are often interpreted as
ultrafast outflows. The velocity is of course present in the orbital
motions of the inner disc. The absorption lines in IRAS 13224-3809 are
best seen when the flux is low and the reflection component of the disc
is strong relative to the power-law continuum. The spectra are
consistent with a model in which the reflection component passes through
a thin, highly ionized absorbing layer at the surface of the inner disc,
the blueshifted side of which dominates the flux due to relativistic
aberration (the disc inclination is about 70°). No fast outflow need
occurs beyond the disc.
- accretion discs
- black hole physics
- galaxies: Seyfert