This paper presents the first direct estimate of the 3D clustering properties of far-infrared sources up to z \sim 3 .
This has been possible thanks to the Pacs Evolutionary Probe ( PEP ) survey of the GOODS South field performed with the PACS instrument onboard the Herschel Satellite .
550 and 502 sources were detected respectively in the 100 \mu m and in the 160 \mu m channels down to fluxes S _ { 100 \mu m } = 2 mJy and S _ { 160 \mu m } = 5 mJy , cuts which ensure > 80 % completeness of the two catalogues .
More than 65 % of these sources has an ( either photometric or spectroscopic ) redshift determination from the MUSIC catalogue , this percentage rising to \sim 95 % in the inner portion of GOODS South which is covered by data at other wavelengths .
An analysis of the de-projected two-point correlation function w ( \theta ) over the whole redshift range spanned by the data reports for the ( comoving ) correlation length , r _ { 0 } \sim 6.3 Mpc and r _ { 0 } \sim 6.7 Mpc , respectively at 100 \mu m and 160 \mu m , corresponding to dark matter halo masses M \mathrel { \hbox to 0.0 pt { \lower 3.0 pt \hbox { $ \sim$ } } \raise 2.0 pt \hbox { $ > $ } } 10 ^ { % 12.4 } M _ { \odot } , in excellent agreement with previous estimates obtained for mid-IR selected sources in the same field .
Objects at z \sim 2 instead seem to be more strongly clustered , with r _ { 0 } \sim 19 Mpc and r _ { 0 } \sim 17 Mpc in the two considered PACS channels .
This dramatic increase of the correlation length between z \sim 1 and z \sim 2 is connected with the presence , more visible at 100 \mu m than in the other band , of a wide ( at least 4 Mpc across in projection ) , M \mathrel { \hbox to 0.0 pt { \lower 3.0 pt \hbox { $ \sim$ } } \raise 2.0 pt \hbox { $ > $ } } 10 ^ { % 14 } M _ { \odot } , filamentary structure which includes more than 50 % of the sources detected at z \sim 2 .
An investigation of the properties of such sources indicates the possibility for boosted star-forming activity in those which reside within the overdense environment with respect of more isolated galaxies found in the same redshift range .
If confirmed by larger datasets , this result can be explained as due to the combined effect of large reservoirs of gas available at high redshifts in deep potential wells such as those associated to large overdensities and the enhanced rate of encounters between sources favoured by their relative proximity .
Lastly , we also present our results on the evolution of the relationship between luminous and dark matter in star-forming galaxies between z \sim 1 and z \sim 2 .
We find that the increase of ( average ) stellar mass in galaxies < M _ { * } > between z \sim 1 and z \sim 2 is about a factor 10 lower than that of the dark matter haloes hosting such objects ( < M _ { * } > ^ { z \sim 1 } / < M _ { * } > ^ { z \sim 2 } \sim 4 \cdot 10 ^ { -1 } vs M _ { halo } ^ { z \sim 1 } / M _ { halo } ^ { z \sim 2 } \sim 4 \cdot 10 ^ { -2 } ) .
When compared with recent results taken from the literature , our findings agree with the evolutionary picture of downsizing wherby massive galaxies at z \sim 2 were more actively forming stars than their z \sim 1 counterparts , while at the same time contained a lower fraction of their mass in the form of luminous matter .