Observational Signatures of the Magnetic Connection between a Black Hole and a Disk

In this Letter we use a simple model to demonstrate the observational signatures of the magnetic connection between a black hole and a disk: (1) With the magnetic connection more energy is dissipated in and radiated away from regions close to the center of the disk; (2) The magnetic connection can produce a very steep emissivity compared to the standard accretion; (3) The observational spectral signature of the magnetic connection can be robust. These signatures may be identified with the observations of Chandra and XMM-Newton. In fact, the steep emissivity index for the Seyfert 1 galaxy MCG–6-30-15 inferred from the recent XMM-Newton observation is very difficult to be explained with a standard accretion disk but can be easily explained with the magnetic connection between a black hole and a disk.