The Herschel Virgo Cluster Survey XVIII. Star-forming dwarf galaxies in a cluster environment

International audienceTo assess the effects of the cluster environment on the different components of the interstellar medium, we analyse the far infrared (FIR) and submillimetre (submrn) properties of a sample of star-forming dwarf galaxies detected by the Herschel Virgo Cluster Survey (HeViCS). We determine dust masses and dust temperatures by fitting a modified black body function to the spectral energy distributions (SEDs). Stellar and gas masses, star formation rates (SERs), and metallicams are obtained from the analysis of a set of ancillary data. Dust is detected in 49 out of a total 140 optically identified dwarfs covered by the HeViCS field; considering only dwarfs brighter than rn8 = 18 rnag, this gives a detection rate of 43%, After evaluating different emissivity indices. we find that the FIR-submin SEDs are best-tit by. beta = 1.5, with a median dust temperature 7'd = 22.4 K. Assuming /3 = 1.5, 67% of the 23 galaxies detected in all five Herschel bands show emission at 500 mu m in excess of the modified black body model. The fraction of galaxies with a submillimetre excess decreases for lower values of 13, while a similarly high fraction (54(4) is found if a beta-free SED modelling is applied. The excess is inversely correlated with SFR and stellar masses. To study the variations in the global properties of our sample that come from environmental effects, we compare the Virgo dwarfs to other Herschel surveys, such as the Key Insights into Nearby Galaxies: Far-Infrared Survey with Herschel (KINGFISH), the Dwarf Galaxy Survey (DGS), and the fleViCS Bright Galaxy Catalogue (BGC). We explore the relations between stellar mass and HI fraction, specific star formation rate. dust fraction, gas-to-dust ratio over a wide range of stellar masses (from 10(7) to 10(11) M-circle dot) for both dwarfs and spirals. Highly Hi deficient Virgo dwarf galaxies are mostly characterised by quenched star formation activity and lower dust fractions giving hints for dust stripping in cluster dwarfs. However, to explain the large dust-to-gas mass ratios observed in these systems, we find that the fraction of dust removed has to be less than that of the HI component. The cluster environment seems to mostly affect the gas component and star formation activity of the dwarfs. Since the Virgo star-forming dwarfs are likely to be crossing the cluster for the first time, a longer timescale might be necessary to strip the more centrally concentrated dust distribution