Astronomy and Astrophysics – Astrophysics
Scientific paper
2006-06-05
Mon.Not.Roy.Astron.Soc.371:81-92,2006
Astronomy and Astrophysics
Astrophysics
13 Pages. 5 colour figures. Accepted for publication in MNRAS
Scientific paper
10.1111/j.1365-2966.2006.10645.x
The origin of the soft X-ray excess emission observed in many type-1 AGN has been an unresolved problem in X-ray astronomy for over two decades. We develop the model proposed Gierlinski & Done (2004), which models the soft excess with heavily smeared, ionized, absorption, by including the emission that must be associated with this absorption. We show that, rather than hindering the ionized absorption model, the addition of the emission actually helps this model reproduce the soft excess. The emission fills in some of the absorption trough, while preserving the sharp rise at ~1 keV, allowing the total model to reproduce the soft excess curvature from a considerably wider range of model parameters. We demonstrate that this model is capable of reproducing even the strongest soft X-ray excesses by fitting it to the XMM-Newton EPIC PN spectrum of PG1211+143, with good results. The addition of the emission reduces the column density required to fit these data by a factor ~2 and reduces the smearing velocity from ~0.28c to ~0.2c. Gierlinski & Done suggested a tentative origin for the absorption in the innermost, accelerating, region of an accretion disk wind, and we highlight the advantages of this interpretation in comparison to accretion disk reflection models of the soft excess. Associating this material with a wind off the accretion disk results in several separate problems however, namely, the radial nature, and the massive implied mass-loss rate, of the wind. We propose an origin in a 'failed wind', where the central X-ray source is strong enough to over-ionize the wind, removing the acceleration through line absorption before the material reaches escape velocity, allowing the material to fall back to the disk at larger radii.
Done Christine
Schurch Nicholas J.
No associations
LandOfFree
Failed disk winds; a physical origin for the soft X-ray excess? does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Failed disk winds; a physical origin for the soft X-ray excess?, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Failed disk winds; a physical origin for the soft X-ray excess? will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-541803