How galaxies keep their cool in the heat: The evolution of galaxies in cosmic filaments, from the field to the heart of clusters

The evolution of galaxies is strongly impacted by their immediate environment. For instance, It is well-established that the dense, hot medium inside clusters (ICM) efficiently strips galaxies flying through it of their cold gas and stars. It therefore prevents further star formation and strongly disturbs a galaxy’s dynamics. The impact of the cosmic environment on Mega-parsec scales is however a more recent field of study.

In the first part of my talk, I will show how simulations and observations alike confirm that the “cosmic web” — the sprawling network of filaments and nodes along which galaxies drift, accrete gas and merge — drives key properties of galaxies. This includes their angular momentum, star formation rate, shape, size, structure and more. I will show that these effects are crucially driven by the dynamics of the gas in and around filaments and not only by density considerations. I will explain how integral-field spectroscopy plays a growing role in demonstrating the origin of these trends.

A missing piece in understanding this interplay is the connection between the “cosmic web” and the local, highly disturbed environment of each galaxy. On the example of clusters and massive groups, I will show how we can explore these liminal spaces where large-scale structures become ambient circum-galactic medium and why they are important. I will show in particular that groups can contain remnants of cosmic filaments which constrain the orbits of satellites down to dwarf scales. In clusters, I will show that these remnants can shield galaxies in their midst from stripping, strangulation and more generally quenching.

A precise quantification of these effects requires elaborate mocks that can directly be compared to observations of clusters with ALMA, Hector or the up-coming Nancy Grace Roman telescope. I will present a new suite of simulations centred on clusters and massive groups, boasting unprecedented resolution (34 pc) for their volume (~10 Mpc) and density. I will explain how these can be used to track the fate of filamentary remnants in clusters in unprecedented details and to produce predictions for up-coming surveys.