Iron line profiles from black hole accretion discs with spiral velocity structure

We calculate the iron line profiles from accretion discs with spiral velocity structures around Schwarzschild black holes. We find that quasi-periodic bumps appear in the the profiles, thereby providing a test for spiral wave patterns. This study is motivated by recent work showing that spiral density waves can result from MHD instabilities even in non-self-gravitating discs, and by improved spectral resolution of forthcoming X-ray missions.