Galaxies 09: Assembly, Gas Content and Star Formation History of Galaxies
Jessica Krick
Spitzer Science Center
The First UV Intracluster Plume in the Virgo Cluster
We are conducting a multi-wavelength project to explore the intracluster light (ICL) in the Virgo cluster as a record of the interaction history and evolution of galaxies in clusters. We have discovered the first ever ICL feature in the UV with {\it GALEX}. This feature is $\sim 50$ kpc long, $\sim 40$ kpc from the interacting galaxy pair NGC4438/4435, and is spatially coincident with an ICL plume detected in the deep V--band imaging of Mihos et al. (2005). The presence of this feature in the UV is extremely surprising because previous optical analyses indicate that intracluster stars are old, and should therefore be undetected in the UV. Spectral energy distribution (SED) fitting of the {\it GALEX} and optical data of this plume reveal not only a population of young intracluster stars but also the first substantial evidence for significant amounts of intracluster dust. We have recently been awarded deep {\it Spitzer} Warm IRAC 3.6 and 4.5 micron data and have proposed for deeper {\it GALEX} FUV and NUV imaging over the central square degree of the Virgo cluster. The complete dataset from UV to IR will allow us to explore the SED of the ICL in unprecedented detail to constrain the origin of the ICL and understand the so far unexplained high metallicity of the intracluster medium. The intracluster features we have already discovered, and those we are likely to discover with coming data are good targets for follow-up observations with ALMA and EVLA to understand what the gas is doing in relation to the stars and dust which will inform models on the origin of the intracluster light and the formation of galaxy clusters.
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