Solving The Puzzle of The Variable Narrow Iron Line in Mrk 841

Iron lines are observed ubiquitously in AGN, offering a powerful probe of theblack hole surroundings. Mrk 841 provides a puzzling case in which the narrowiron line, usually associated with the torus or the broad line region, varies onhours time scales. This can be due either an unusually small emission region forthe narrow line, or due to hot spots orbiting very close to the black hole whoseemission is occasionally Dopplerboosted. With the source visibility nowallowing for long exposures, we propose to observe it for two orbits,simultaneously with NuSTAR, to solve the puzzle. Confirming any of the proposedmechanisms offer an exciting opportunity to unravel unprecedented details aboutthe line emission region. truncated!, Please see actual data for full text [truncated!, Please see actual data for full text]