VIRAGE: Virgo - Alterations of Galaxies within dense Environments – VIRAGE

Our goal is to provide a reference analysis of galaxies in these different cluster environments that is statistically complete in range of galaxy mass and multi-wavelength coverage. This is only possible because of its proximity, which makes of Virgo the only galaxy cluster in which baryonic structures can be studied in such great detail, from the brightest to the very faintest galaxies, and including the extremely faint tidal structures around them.

Our research led to the discovery of multiple dwarf destruction around a bombarded spiral galaxy in the Virgo cluster, and to the identification of the oldest Tidal Dwarf galaxy known so far in the nearby Universe. We identified new low surface brightness galaxies. We characterize Virgo galaxies mulch-wavelength properties.

We are extending our work to further quantify how environmental effects are important for galaxy evolution.

Our results have been published in 47 refereed papers

VIRAGE in French means turn/change of direction. Galaxies are evolving systems that experience transformations during their lifetime: their orbits, mass accretion and star formation histories and finally morphology all change. This happens in the context of a living Universe in which structures assemble by the gravitational growth of initial dark matter fluctuations to create the massive galaxy clusters we observe today. How much galaxy transformations are driven by the physics of this gravitational assembly and how much by the physics of baryons is one of the most hotly debated questions today. The underlying key question is whether the dominant processes are internal to galaxies (nature) or due to their interactions with the environment (nurture).

We address this question by a detailed characterization of environmental effects within the densest environment of the nearby Universe, the Virgo galaxy cluster. We aim to examine in greater detail than ever before the galaxies in this system, their interactions and the interaction with their surrounding medium in the core of the cluster as well as its peripheral regions. Our goal is to provide a reference analysis of galaxies in these different cluster environments that is statistically complete in range of galaxy mass and multi-wavelength coverage. This is only possible because of its proximity, which makes of Virgo the only galaxy cluster in which baryonic structures can be studied in such great detail, from the brightest to the very faintest galaxies, and including the extremely faint tidal structures around them.

Over the next few years, a wealth of surveys of this cluster will revolutionize the way we study it, because of their unprecedented depth, spatial and wavelength coverage. They will discover new objects and expand our insight on the star formation and interacting history of galaxies in this remarkable system. The strength of our team lies in our involvement in all of these major surveys, as either PIs or Co-Is . Our collaboration will therefore have the access, resources and expertise to fully capitalize on this outstanding data set.

Our analysis will primarily draw on three surveys: the Next Generation Virgo Survey, the NGVS-IR, and GUViCS, combined with complementary data when needed for our scientific goals. We propose to combine the unique data from these three surveys to characterize the effects of environment on galaxy star formation histories, spatial distribution, and on the intragalactic medium. Our analysis will:
-discover new faint galaxies and low surface brightness features (tidal tails, stellar streams)
-produce a distance catalog of Virgo galaxies and examine environmental signatures as a function of local (instead of projected) galaxy density
-enable spectro-chemical modeling of environmental effects on galaxy spectral energy distributions, and the reconstruction of galaxy star formation histories from the brightest to the faintest objects

When completed, our results will be used for decades as benchmarks in the characterization of galaxies changing in a dense environment, from the most massive to the very faintest, and a reference for future comparison of galaxies in the field.