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NGC 5548: LACK OF A BROAD Fe Kα LINE AND CONSTRAINTS ON THE LOCATION OF THE HARD X-RAY SOURCE.
- Source :
-
Astrophysical Journal . Jan2012, Vol. 744 Issue 1, Special section p1-15. 15p. - Publication Year :
- 2012
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Abstract
- We present an analysis of the co-added and individual 0.7-40keV spectra from seven Suzaku observations of the Sy 1.5 galaxy NGC 5548 taken over a period of eight weeks. We conclude that the source has a moderately ionized, three-zone warm absorber, a power-law continuum, and exhibits contributions from cold, distant reflection. Relativistic reflection signatures are not significantly detected in the co-added data, and we place an upper limit on the equivalent width of a relativistically broad Fe Kα line at EW ≤ 26 eV at 90% confidence. Thus NGC 5548 can be labeled as a "weak" type 1 active galactic nucleus (AGN) in terms of its observed inner disk reflection signatures, in contrast to sources with very broad, strong iron lines such as MCG-6-30-15, which are likely much fewer in number. We compare physical properties of NGC 5548 and MCG-6-30-15 that might explain this difference in their reflection properties. Though there is some evidence that NGC 5548 may harbor a truncated inner accretion disk, this evidence is inconclusive, so we also consider light bending of the hard X-ray continuum emission in order to explain the lack of relativistic reflection in our observation. If the absence of a broad Fe Kα line is interpreted in the light-bending context, we conclude that the source of the hard X-ray continuum lies at radii rs ≳ 100rg. We note, however, that light-bending models must be expanded to include a broader range of physical parameter space in order to adequately explain the spectral and timing properties of average AGNs, rather than just those with strong, broad iron lines. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 0004637X
- Volume :
- 744
- Issue :
- 1
- Database :
- Academic Search Index
- Journal :
- Astrophysical Journal
- Publication Type :
- Academic Journal
- Accession number :
- 72653843
- Full Text :
- https://doi.org/10.1088/0004-637X/744/1/13