A CHANDRA HETGS SPECTRAL STUDY OF THE IRON K BANDPASS IN MCG-6-30-15: A NARROW VIEW OF THE BROAD IRON LINE

摘要

We present a 522ksec Chandra High Energy Transmission Grating Spectrometer (HETGS) observation of the Fe K bandpass of MCG-6-30-15. The Chandra spectrum shows a broad Fe Ka line, consistent with a relativistic disk line. Narrow, blue-shifted H- and He-like Fe absorption lines are detected, with a likely origin in a≈2000kms{sup}(-1) outflow. No other narrow absorption lines are detected in the Fe K bandpass. The gas giving rise to the H- and He-like Fe absorption lines is very highly ionized and does not affect the ～2-6keV continuum shape. Less highly ionized absorption could alter the ～2-6keV continuum shape and reduce the extent of the red wing of the iron line but a generic prediction of such models are narrow absorption lines between ～6.4-6.5keV which are inconsistent with the Chandra spectrum. Furthermore, the difference spectrum between the high flux and low flux states shows no deviation from a power law between 2 and 6keV, contrary to the predictions of simple absorption models. These are compelling arguments that the broad iron Kα line is not significantly affected by complex ionized absorption. We conclude that the relativistic disk line interpretation of the broad iron Kα line in MCG-6-30-15 is robust.