2000ApJ...530..282K

The Westerbork Northern Sky Survey (WENSS) and the NRAO/VLA Sky Survey were used to determine an upper limit to the diffuse radio flux from the nearby cluster Abell 2199. For the entire cluster, this limit is less than 3.25 Jy at 327 MHz from WENSS; for the inner 15' radius, the limit is less than 168 mJy at 1.4 GHz. These limits are used to constrain the cluster magnetic field by requiring that the radio flux be consistent with the hard X-ray (HXR) flux observed by BeppoSAX, assuming that the observed HXR excess is the result of inverse Compton scattering of cosmic microwave background photons by relativistic electrons in the intracluster gas. We find that the magnetic field must be very weak (<0.073 µG) in order to avoid producing an observable radio halo. We also consider the possibility that the HXR excess is the result of nonthermal bremsstrahlung (NTB) by a population of suprathermal electrons that are being accelerated to higher energies. We find that a NTB model based on a power-law electron-momentum distribution with an exponent of µ~3.3 and containing about 5% of the number of electrons in the thermal ICM can reproduce the observed HXR flux.