Title: Anatomy of an X-ray detected cluster at z = 2: low metallicities and enhanced specific star 
formation rates in star-forming galaxies.

Abstract:
The most distant spectroscopically confirmed cluster known to date, CL J1449+0856 at z=2, 
represents a unique laboratory to study galaxy evolution in dense environments at high redshifts 
and, in the past few years, a systematic multiwavelength campaign allowed us to test the 
current understanding of environment-driven processes in galaxies.    Surprisingly, recent 
Subaru and HST spectroscopic follow-ups revealed lower metallicities and higher sSFRs in 
cluster star-forming galaxies than in mass-matched field counterparts. This 
somewhat unexpected behaviour can be possibly due to an enhanced accretion of pristine gas 
from the environment and/or facilitated by recent or ongoing merging activity, something 
probably linked to the recent assembly of its dark matter halo. The further discovery of a giant 
Lya halo residing in the cluster core in a narrow-band imaging follow-up and the presence of 
very strong diffuse light in the near-IR support the idea of a physical connection between Mpc-
scale environment and galaxy evolution at the peak of cosmic star formation history at z~2. 
Forthcoming KMOS observations will allow us to test different gas-enrichment scenarios 
constraining metallicity gradients, while partial overlap with our ongoing ALMA observation will 
shed light on the molecular gas content of these objects.