Different types of Fe Kα lines from radiating annuli near black holes

Recent X-ray observations of microquasars and Seyfert galaxies reveal the broad emission lines in their spectra, which can arise in the innermost parts of accretion disks. A theoretical analysis of observations and their interpretations were discussed in a number of papers. We consider a radiating annulus model to simulate spectral line shapes. That is a natural approximation for narrow emitting circular rings without extra astrophysical assumptions about emissivity laws. Recently, Müller and Camenzind [Müller, A., Camenzind, M., 2004. A&A 413, 861] presented results of their calculations and classified different types of spectral line shapes and described their origin. We clarified their hypothesis about an origin of double peaked and double horned line shapes. Based on results of numerical simulations we showed that double peaked spectral lines arise almost for any locations of narrow emission rings (annuli) although Müller and Camenzind [Müller, A., Camenzind, M., 2004. A&A 413, 861] suggested that such profiles arise for relatively flat space-times and typical radii for emission region about 25rg. We showed that triangular spectral lines could arise for nearest annuli and high inclination angles. We discuss a possibility of appearance of narrow spectral line shapes as a result of spiralling evolution of matter along quasi-circular orbits which could be approximated by narrow annuli.