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The search of extragalactic regions with conspicuous presence of Wolf-Rayet(WR) stars outside the Local Group is challenging task due to the difficultiesin detecting their faint spectral features. In this exploratory work, wedevelop a methodology to perform an automated search of WR signatures through apixel-by-pixel analysis of integral field spectroscopy (IFS) data belonging tothe Calar Alto Legacy Integral Field Area survey, CALIFA. This techniqueallowed us to build the first catalogue of Wolf-Rayet rich regions withspatially-resolved information, allowing to study the properties of thesecomplexes in a 2D context. The detection technique is based on theidentification of the blue WR bump (around He II 4686 {\AA}, mainly associatedto nitrogen-rich WR stars, WN) and the red WR bump (around C IV 5808 {\AA} andassociated to carbon-rich WR stars, WC) using a pixel-by-pixel analysis. Weidentified 44 WR-rich regions with blue bumps distributed in 25 galaxies of atotal of 558. The red WR bump was identified only in 5 of those regions. Wefound that the majority of the galaxies hosting WR populations in our sampleare involved in some kind of interaction process. Half of the host galaxiesshare some properties with gamma-ray burst (GRB) hosts where WR stars, aspotential candidates to being the progenitors of GRBs, are found. We alsocompared the WR properties derived from the CALIFA data with stellar populationsynthesis models, and confirm that simple star models are generally not able toreproduce the observations. We conclude that other effects, such as the binarystar channel (which could extend the WR phase up to 10 Myr), fast rotation orother physical processes that causes the loss of observed Lyman continuumphotons, are very likely affecting the derived WR properties, and hence shouldbe considered when modelling the evolution of massive stars.

First survey of Wolf-Rayet star populations over the full extension of nearby galaxies observed with CALIFA