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Search for H alpha emitters in Galaxy Clusters with Tunable Filters

The studies of the evolution of galaxies in Galaxy Clusters have as a traditional complication the difficulty in establishing cluster membership of those sources detected in the field of view. The determination of spectroscopic redshifts involves long exposure times when it is needed to reach the cluster peripherical regions of/or clusters at moderately large redshifts, while photometric redshifts often present uncertainties too large to offer significant conclusions. The mapping of the cluster of galaxies with narrow band tunable filters makes it possible to reach large redshifts intervals with an accuracy high enough to establish the source membership of those presenting emission/absorption lines easily identifiable, as H alpha. Moreover, the wavelength scan can include other lines as [NII], [OIII] or $H_β$ allowing to distinguish those sources with strong stellar formation activity and those with an active galactic nuclei. All this makes it possible to estimate the stellar formation rate of the galaxies observed. This, together with ancillary data in other wavelengths may lead to a good estimation of the stellar formation histories. It will shed new light over the galaxy evolution in clusters and will improve our understanding of galaxy evolution, especially in the outer cluster regions, usually less studied and with significant unexploited data that can not be correctly interpreted without redshift determination.