Magnetic flares and the observed pi(T)similar to 1 in Seyfert galaxies

We here consider the pressure equilibrium during an intense magnetic flare above the surface of a cold accretion disk. Under the assumption that the heating source for the plasma trapped within the flaring region is an influx of energy transported inward with a group velocity close to c, e.g., by magnetohydrodynamic waves, this pressure equilibrium can constrain the Thomson optical depth, tau(T), to be of order unity. We suggest that this may be the reason why tau(T) similar to 1 in Seyfert galaxies. We also consider whether current data can distinguish between the spectrum produced by a single X-ray-emitting region with tau(T) similar to 1 and that formed by many different flares spanning a range of tau(T). We find that the current observations do not yet have the required energy resolution to permit such a differentiation. Thus, it is possible that the entire X-ray/gamma-ray spectrum of Seyfert galaxies is produced by many independent magnetic hares with an optical depth of 0.5 < tau(T) < 2.