Velocity gradients in the intracluster gas of the Perseus Cluster

We report the results of spatially resolved X-ray spectroscopy of eight different ASCA pointings distributed symmetrically around the center of the Perseus Cluster. The outer region of the intracluster gas is roughly isothermal, with temperature similar to6-7 keV and metal abundance similar to0.3 solar. Spectral analysis of the central pointing is consistent with the presence of a cooling flow and a central metal abundance gradient. A significant velocity gradient is found along an axis at a position angle of similar to 135 degrees, which is similar to 45 degrees discrepant with the major axis of the X-ray elongation. The radial velocity difference is found to be greater than 1000 km s(-1) Mpc(-1) at the 90% confidence level. Simultaneous fittings of GIS 2 and 3 indicate that the velocity gradient is significant at the 95% confidence level, and the F-test rules out constant velocities at the 99% level. Intrinsic short- and long-term variations of gain are unlikely (P < 0.03) to explain the velocity discrepancies.