Dust processing in extreme environments

The Herschel Virgo Cluster Survey (HeViCS) unveiled evidence for extra planar galactic dust around a few galaxies in the Virgo Cluster. Phenomena like ram pressure stripping or collisions between galaxies can explain the presence of dust in the intergalactic medium (IGM) therefore leading to the metal enrichment of the medium itself. However, the IGM is a very extreme environment for dust grains. The collision of fast ions and electrons with dust leads to both destruction and heating (Micelotta et al. 2010a; Bocchio et al. 2012, 2013). It is therefore expected that the emission from the small grains embedded within a hot gas will be significantly reduced by erosion on rather short timescales, making these grains difficult to observe in these extreme environments. As an example, I selected the galaxy NGC 4438, a perturbed galaxy close to the Virgo Cluster centre. This galaxy shows mixing between the interstellar medium (ISM) and the IGM leading to an enhancement of the X-ray luminosity. Comparing the full dust spectral energy distribution (SED), as detected by Spitzer and Herschel, with the modeled dust SED in different regions around this galaxy we can retrieve information on the dust processing and heating (Bocchio et al., in preparation).