Revisiting the relativistic broad Fe line

Inoue, H.

ISAS, Sagamihara, Kanagawa, Japan


The discovery of the broad and skewed line-feature around 5 -- 7 keV in 
spectra of Seyfert galaxies is one of the most remarkable results from 
ASCA.  Such a line profile is well explained with the so-called 
``disk-line" model and the presence of these lines is regarded to be the 
first direct observational evidence of the existence of a central black 
hole.  However, the disk-line model is still one spectral model to 
reproduce the spectral feature around 5 -- 7 keV and it is obviously very 
important to check the validity and correctness of the ``disk-line" 
interpretation as strictly as possible.  Here, I shall present results of 
time-variability-study of the disk-line profile in the spectra of 
MCG--6-30-15 and NGC4151 from such a point of view.  Both results rather 
suggest that the ``disk-line" profile could be a combination of a fairly 
narrow line at 6.4 keV and a broad hump around 5 -- 7 keV.  The broad hump 
could be a heavily absorbed continuum component, which should be reflected 
by some ambient matter responsible for the 6.4 keV line and sometimes 
suffer an absorption by warm absorbers.