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]

We confirm the detection of the relativistically broadened iron K-alphaemission at 6.4 keV with simultaneous Chandra HETGS and RXTE PCA observations.Heavily binned HETGS data show a disk line profile with parameters very similarto those previously seen by ASCA. We observe a resolved narrow component with avelocity width ~4700 km/s (FWHM ~ 11,000 km/s), that is most prominent, andnarrower (FWHM ~ 3600 km/s) when the continuum flux is high. It plausibly isjust the blue wing of the broad line. We obtain a stringent limit on theequivalent width of an intrinsically narrow line in the source of 16 eV,indicating little or no contribution due to fluoresence from distant materialsuch as the molecular torus. Variability studies of the narrow component show aconstant iron line flux and variable width indicating the line may beoriginating from different kinematic regions of the disk.Comment: Accepted for publication in the Astrophysical Journal Letter