SIMBAD references

1998A&A...333..411V - Astronomy and Astrophysics, volume 333, 411-416 (1998/5-2)

ASCA detection of the FeK edge in the spectrum of the Seyfert 2 galaxy IRAS 04575-7537: a sign of a complex absorber.

VIGNALI C., COMASTRI A., STIRPE G.M., CAPPI M., PALUMBO G.G.C., MATSUOKA M., MALAGUTI G. and BASSANI L.

Abstract (from CDS):

ASCA X-ray spectral analysis of the Seyfert 2 galaxy IRAS 04575-7537 is presented. The main result is the presence of a significant iron edge at a rest energy of 7.13+0.21–0.16keV. The spectrum is flat ({GAMMA}∼1.5) with a substantial absorption: NH∼1022cm–2 and does not require any reflection component. There is also evidence of a narrow FeKα emission line, whose rest energy (E=6.35+0.08–0.03keV) and equivalent width (EW≃130±50eV) suggest that the line originates from thick and cold matter. The intensity of the line and, in particular, the depth of the iron edge are too strong to be explained by simple transmission through the measured absorption column density. This strongly suggests that a model more complex than a single absorbed power law is needed. We propose an absorption model that we call ``leaky-total absorber'' which can explain the spectrum flatness, the iron emission line and the edge absorption feature and has also the advantage of having a straightforward physical interpretation in the framework of Unified models. In this model a thick absorber (NH∼1023cm–2), possibly associated with broad line region (BLR) clouds, partially (∼36%) covers the source continuum with {GAMMA} fixed to 1.9 as observed in Sey 1 galaxies. The escaping radiation is then absorbed by a column density NH∼1022cm–2, which can be attributed to the torus, seen through its rim.

Abstract Copyright:

Journal keyword(s): X-rays: galaxies - galaxies: active - galaxies: Seyfert - galaxies: individual: IRAS 04575-7537 - galaxies: emission lines

Simbad objects: 3

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