Warm absorber and truncated accretion disc in IRAS 05078+1626
Abstract
Context. X-ray observations of unabsorbed active galactic nuclei provide an opportunity to explore the innermost regions of supermassive black hole accretion discs.
Aims: Our goal in this paper is to investigate the central environment of a Seyfert 1.5 galaxy IRAS 05078+1626.
Methods: We studied the time-averaged spectrum obtained with the EPIC and RGS instruments onboard XMM-Newton.
Results: A power law continuum (photon index Γ ≃ 1.75) dominates the 2-10 keV energy range. A narrow iron K α spectral line is clearly seen, presumably originating in a distant torus, but no broad relativistic component was detected. However, the power law and the iron K α line alone do not provide a satisfactory fit in the soft X-ray band whose spectrum can be explained by the combination of three components: a) a cold photoelectric absorber with column density NH ≈ 1021 cm-2. This gas could be located either in outer parts of the accretion disc, at the rim of the torus or farther out in the host galaxy; b) a warm absorber with high ionization parameter (log ξ ≈ 2.2) and column density (NH ≈ 1024 cm-2); c) an ionised reflection where the reflecting gas could be either in the inner wall of a warm absorber cone or in an ionised accretion disc.
Conclusions: The first X-ray spectroscopic measurement of IRAS05078+1626 unveils some of the standard ingredients in Seyfert galaxies, such as a power law primary continuum, modified by reflection from the accretion disc and by the effect of complex, multi-phase obscuration. However, data constrains the accretion disc, if present, not to extend closer than to 60 gravitational radii from the black hole.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- March 2010
- DOI:
- 10.1051/0004-6361/200913659
- arXiv:
- arXiv:0912.5165
- Bibcode:
- 2010A&A...512A..62S
- Keywords:
-
- galaxies: active;
- galaxies: Seyfert;
- galaxies: individual: IRAS 05078+1626;
- Astrophysics - Cosmology and Nongalactic Astrophysics
- E-Print:
- 8 pages, 10 figures, accepted to Astronomy and Astrophysics