A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE)

The Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) survey is a blind narrow-band Hα + [N <ns0:sc>II</ns0:sc>] imaging survey of the Virgo cluster carried out with MegaCam of the Canada-France-Hawaii Telescope. The survey provides deep narrow-band images for 385 galaxies hosting star-forming H <ns0:sc>II</ns0:sc> regions. We identify individual H <ns0:sc>II</ns0:sc> regions and measure their main physical properties such as Hα luminosity, equivalent diameter, and electron density with the purpose of deriving standard relations that can serve as a reference for future local and high-z studies of H <ns0:sc>II</ns0:sc> regions in star-forming systems in different environments. For this purpose, we used a complete sample of ≃13.000 H <ns0:sc>II</ns0:sc> regions of luminosity L(Hα)≥1037 erg s−1 in order to derive the main statistical properties of H <ns0:sc>II</ns0:sc> regions in unperturbed systems, which are identified as those galaxies with a normal H <ns0:sc>I</ns0:sc> gas content, and are in total 64 objects. These are the composite Hα luminosity function, equivalent diameter and electron density distribution, and luminosity-size relation. We also derived the main scaling relations between several parameters representative of the H <ns0:sc>II</ns0:sc> regions (total number, luminosity of the first ranked regions, fraction of the diffuse component, best-fit parameters of the Schechter luminosity function measured for individual galaxies) and those characterising the properties of the host galaxies (stellar mass, star formation rate and specific star formation rate, stellar mass and star formation rate surface density, metallicity, molecular-to-atomic gas ratio, total gas-to-dust mass ratio). We briefly discuss the results of this analysis and their implications in the study of the star formation process in galaxy discs.