The Shape of the Relativistic Iron Kα Line from MCG −6-30-15 Measured with the [ITAL]Chandra[/ITAL] High Energy Transmission Grating Spectrometer and the [ITAL]Rossi X-Ray Timing Explorer[/ITAL]

Abstract

We confirm the detection of the relativistically broadened iron Ka emission at 6.4 keV with simultaneous Chandra High Energy Transmission Grating Spectrometer (HETGS) and Rossi X-Ray Timing Explorer Proportional Counter Array observations. Heavily binned HETGS data show a disk line profile with parameters very similar to those previously seen by ASCA. We observe a resolved narrow component with a velocity width of ∼4700 km s 1 (FWH km s 1) that is most prominent and is narrower (FWH km s 1) when the continuum M ∼ 11,000 M ∼ 3600 flux is high. It is plausibly just the blue wing of the broad line. We obtain a stringent limit on the equivalent width of an intrinsically narrow line in the source of 16 eV, indicating little or no contribution due to fluorescence from distant material, such as the molecular torus. Variability studies of the narrow component show a constant iron line flux and variable width indicating the line may be originating from different kinematic regions of the disk.