optical observations of bright elliptical galaxies in the virgo cluster: stellar population and distance analysis

the analysis of deep imaging data of bright elliptical galaxies is capable of providing fundamental information on the stellar content and the distance of the target, via the surface brightness fluctuation method (sbf hereafter). here, i present the study of the properties of two ellipticals in the virgo cluster, ngc4621 and ngc4374, based on deep bvr imaging data obtained with the fors2 camera at the vlt. the v and r sbf measures are used to get accurate distances of the targets. in addition, since both galaxies hosted type iasupernova events, i also compare the new sbf distances with the ones based on sne ia lightcurve analysis. in all cases sbf distances agree well with distances obtained by other distance indicators. for what concerns stellar population analysis, i present a detailed comparison between sbf data and models to constrain the properties of the dominant stellar components. among the other results, the measures presented here seem to suggest that the b-band sbf can be reconciled to model predictions only through the presence of a percentage of hot- hb stars “polluting” the old and metal rich dominant stellar population.