We have studied the mass assembly and star formation histories of massive galaxies identified at low redshift z in different cosmological hydrodynamical simulations .
To this end , we have carried out a detailed follow-up backwards in time of their constituent mass elements ( sampled by particles ) of different types .
After that , the configurations they depict at progressively higher z s were carefully analysed .

The analyses show that these histories share common generic patterns , irrespective of particular circumstances .
In any case , however , the results we have found are different depending on the particle type .
The most outstanding differences follow .

We have found that by z \sim 3.5 - 6 , mass elements identified as stellar particles at z = 0 exhibit a gaseous cosmic-web-like morphology with scales of \sim 1 physical Mpc , where the densest mass elements have already turned into stars by z \sim 6 .
These settings are in fact the densest pieces of the cosmic web , where no hot particles show up , and dynamically organised as a hierarchy of flow convergence regions ( FCRs ) , that is , attraction basins for mass flows .
At high z FCRs undergo fast contractive deformations with very low angular momentum , violently shrinking them .
Indeed , by z \sim 1 most of the gaseous or stellar mass they contain shows up as bound to a massive elliptical-like object at their centers , with typical half mass radii of r _ { star } ^ { mass } \sim 2 - 3 kpc .
After this , a second phase comes about where the mass assembly rate is much slower and characterised by mergers involving angular momentum .

On the other hand , mass elements identified at the diffuse hot coronae surrounding massive galaxies at z = 0 do not display a clear web-like morphology at any z .
Diffuse gas is heated when FCRs go through contractive deformations .
Most of this gas remains hot and with low density throughout the evolution .

To shed light on the physical foundations of the behaviour revealed by our analyses ( i.e. , a two-phase formation process with different implications for diffuse or shocked mass elements ) , as well as on their possible observational implications , these patterns have been confronted with some generic properties of singular flows as described by the adhesion model ( i.e. , potential character of the velocity field , singular versus regular points , dressing , locality when an spectrum of perturbations is implemented ) .
We have found that the common patterns the simulations show can be interpreted as a natural consequence of flow properties that , moreover , could explain different generic observational results on massive galaxies or their samples .
We briefly discuss some of them .