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We explore the internal dynamics of Abell 2254, which has been shown to hosta very clumpy and irregular radio halo. Our analysis is mainly based onredshift data for 128 galaxies acquired at the TNG. We also use new g',r',i'photometric data acquired at the INT and (V,i') photometric data available inthe Subaru Archive. X-ray data from the XMM-Newton Science Archive are analyzedto study the hot gas component. We estimate the cluster redshift <z>=0.177, ahigh line-of-sight (LOS) velocity dispersion, sigmaV about 1350 km/s, and X-raytemperature T about 6.4 keV. Both our optical and X-ray analyses reveal acomplex dynamical activity. The analysis of the 2D galaxy distribution revealsthe presence of two density peaks, one at the East and the other at the West.Using the full 3D information we detect a high LOS velocity (DeltaV about 3000km/s), low mass group at the position of the 2D eastern peak. For the mainsystem we compute a velocity dispersion sigmaV about 1000-1200 km/s. In theassumption of a bimodal system we estimate a mass M=1.5-2.9 10^15 solarmasses.The X-ray morphological analysis confirms that Abell 2254 is adynamically disturbed cluster. The X-ray isophotes are elongated toward theeastern direction, in agreement with a merger in the post core-crossing phase.A simple bimodal model finds that data are consistent with a bound, outgoingsubcluster observed a few fractions of Gyr after the core crossing. However,both optical and X-ray analyses suggest that the main system is, at its time, anon relaxed structure, indicating N-S as a possible direction for a pastaccretion. We conclude that Abell 2254, for its mass and merging structure,fits well among typical clusters with radio halos. We shortly discuss as theparticular irregularity of the radio halo might be linked to the complexity ofthe Abell 2254 structure.

Internal dynamics of Abell 2254: a merging galaxy cluster with a clumpy, diffuse radio emission