Open AccessReprocessed emission from warped accretion discs with application to X‐ray iron line profiles
Author(s) -
Hartnoll Sean A.,
Blackman Eric G.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03661.x
Subject(s) - physics , astrophysics , accretion (finance) , line (geometry) , accretion disc , context (archaeology) , active galactic nucleus , schwarzschild radius , emission spectrum , geodesic , astronomy , galaxy , geometry , spectral line , paleontology , mathematics , biology
Fluorescent iron line profiles currently provide the best diagnostic for engine geometries of active galactic nuclei (AGN). Here we construct a method for calculating the relativistic iron line profile from an arbitrarily warped accretion disc, illuminated from above and below by hard X‐ray sources. This substantially generalizes previous calculations of reprocessing by accretion discs by including non‐axisymmetric effects. We include a relativistic treatment of shadowing by ray‐tracing photon paths along Schwarzschild geodesics. We apply this method to two classes of warped discs, and generate a selection of resulting line profiles. New profile features include a time‐varying line profile if the warp precesses about the disc, profile differences between ‘twisted’ and ‘twist‐free’ warps and the possibility of steeper red and softer blue fall‐offs than for flat discs. We discuss some qualitative implications of the line profiles in the context of Type I and II Seyfert AGN and other sources.