Pericentric passage-driven star formation in satellite galaxies and
  their hosts: CLUES from Local Group simulations
  Local Group satellite galaxies show a wide diversity of star formation
histories (SFHs) whose origin is yet to be fully understood. Using
hydrodynamical simulations from the Constrained Local UniversE project, we
study the SFHs of satellites of Milky Way-like galaxies in a cosmological
context: while in the majority of the cases the accretion onto their host
galaxy causes the satellites to lose their gas, with a subsequent suppression
in SF, in about 25$\%$ of our sample we observe a clear enhancement of SF after
infall. Peaks in SF clearly correlate with the satellite pericentric passage
around its host and, in one case, with a satellite-satellite interaction. We
identify two key ingredients that result in enhanced SF after infall: galaxies
must enter the host's virial radius with a reservoir of cold gas $M_{\rm
gas,inf}/M_{\rm vir,inf}\gtrsim 10^{-2}$ and with a minimum pericentric
distance $\gtrsim$10 kpc (mean distance $\sim$50 kpc for the full sample), in
order to form new stars due to compression of cold gas at pericentric passage.
On the other hand, satellites that infall with little gas or whose pericentric
distance is too small, have their gas ram-pressure stripped and subsequent SF
quenched. The pericentric passage of satellites likewise correlates with SF
peaks in their hosts, suggesting that this mechanism induces bursts of SF in
satellites and central galaxies alike, in agreement with recent studies of our
Galaxy's SFH. Our findings can explain the recently reported multiple stellar
populations observed in dwarf galaxies such as Carina and Fornax, and should be
taken into account in semi-analytic models of galaxy formation and satellite
quenching.
