XMM-Newton observations of A133:: A weak shock passing through the cool core

We use XMM-Newton observations of the cluster of galaxies A133 to study the X-ray spectrum of the intracluster medium (ICM). We find a cold front to the southeast of the cluster core. From the pressure profile near the cold front, we derive an upper limit to the velocity of the core relative to the rest of the cluster of less than 230 km s(-1). Our previous Chandra image of A133 showed a complex, birdlike morphology in the cluster core. On the basis of the XMM-Newton spectra and hardness ratio maps, we argue that the wings of this structure are a weak shock front. The shock was probably formed outside the core of the cluster and may be heating the cluster core. Our Chandra image also showed a "tongue'' of relatively cool gas extending from the center of the cD galaxy to the center of the radio relic. The XMM-Newton results are consistent with the idea that the tongue is the gas that has been uplifted by a buoyant radio bubble including the radio relic to the northwest of the core. Alternatively, the tongue might result from a cluster merger. The small velocity of the core suggests that the bubble including the relic has been moved by buoyancy rather than by motions of the core or the ICM. We do not find clear evidence for nonthermal X-ray emission from the radio relic. On the basis of the upper limit on the inverse Compton emission, we derive a lower limit on the magnetic field in the relic of B greater than or equal to 1.5 muG.