Active galaxy 4U 1344-60: did the relativistic line disappear?
Abstract
Context. X-ray bright active galactic nuclei represent a unique astrophysical laboratory for studying accretion physics around super-massive black holes.
Aims: 4U 1344-60 is a bright Seyfert galaxy which revealed relativistic reflection features in the archival XMM-Newton observation.
Methods: We present the spectroscopic results of new data obtained with the Suzaku satellite and compare them with the previous XMM-Newton observation.
Results: The X-ray continuum of 4U 1344-60 can be well described by a power-law component with the photon index ≈ 1.7 modified by a fully and a partially covering local absorbers. We measured a substantial decrease of the fraction of the partially absorbed radiation from around 45% in the XMM-Newton observation to less than 10% in the Suzaku observation while the power-law slope remains constant within uncertainties. The iron line in the Suzaku spectrum is relatively narrow, σ = (0.08 ± 0.02) keV, without any suggestion for relativistic broadening. Regarding this, we interpret the iron line in the archival XMM-Newton spectrum as a narrow line of the same width plus an additional red-shifted emission around 6.1 keV.
Conclusions: No evidence of the relativistic reflection is present in the Suzaku spectra. The detected red-shifted iron line during the XMM-Newton observation could be a temporary feature either due to locally enhanced emission or decreased ionisation in the innermost accretion flow.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- September 2012
- DOI:
- 10.1051/0004-6361/201219500
- arXiv:
- arXiv:1209.4068
- Bibcode:
- 2012A&A...545A.148S
- Keywords:
-
- galaxies: active;
- galaxies: Seyfert;
- galaxies: individual: 4U 1344-60;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 10 pages, 11 figures, accepted to A&