Relation between X-ray and optical spectra

We introduce the use of the "correlation spectrum technique" (CST) for the first time. We use this to show the strength of the correlation between the hard X-ray luminosity and each wavelength of the optical spectrum.

This shows that for broad-line Seyfert 1 galaxies all the strong emission lines (the broad component of H{alpha} and H{beta}, [NeIII] {lambda}{lambda}3869/3967, [OI] {lambda}{lambda}6300/6364, [OII] {lambda}{lambda}3726/3729 and [OIII] {lambda}{lambda}4959/5007) and the optical underlying continuum all strongly correlate with the hard X-ray emission. In contrast, the narrow-line Seyfert 1 galaxies show a stronger correlation in the optical continuum but a weaker correlation in the lines.