2. Motivation

3. it is a key diagnostic of the ISM because: [CII] is the dominant cooling line of the ISM

4. Motivation it is a key diagnostic of the ISM because: [CII] is the dominant cooling line of the ISM [CII] arises from different components providing a wide picture of the ISM - diffuse ionized gas (?) - diffuse neutral gas (CNM, WNM) - dense neutral gas (PDR)

5. Capak+2015, Nature [CII] emission in LAEs and LBGs at z~7 Maiolino+2015 Motivation

6. Maiolino+2015 Open issues Capak+2015 Willott+2015 [CII] detection LAEs/LBGs at 5<z<6.6 Maiolino+2015 [CII] detection in the vicinity of a z=7.1 LBG Maiolino+2015 [CII] upper limits Spatial displacement Deviation from the [CII]-SFR relation Relative contribution of the various phases modeling of the ISM in high-z galaxies

7. Column density maps + stellar distribution Vallini+.2013 Emission from the neutral diffuse gas

8. Emission from the PDR see: Hollenbach &Tielens 1999

9. Vallini+2015, ApJ accepted M gas > M Jeans Modeling the [CII] emission from the PDRs molecular clouds Emission from the PDR

10. Cosmological simulation of metal enrichment in high-z galaxies developed by Pallottini+2014 Emission from the PDR Vallini+2015, ApJ accepted

11. Cosmological simulation of metal enrichment in high-z galaxies developed by Pallottini+2014 Emission from the PDR Vallini+2015, ApJ accepted PDRs

12. diffuse gas PDRs ς = 0.1- 0.2 ς = 0.8 -1.0 The T CMB increases as (1+z) hence at high redshift it becomes a stronger background against which we observe the [CII] line. If: T ex ([CII])  T CMB the fraction of the of the intrinsic line flux observed against the CMB radiation approaches to zero. Effect of the increased CMB temperature

13. intrinsic observed Vallini+2015, ApJ accepted Contribution of the diffuse neutral gas

14. Vallini+2015, ApJ accepted Deviation from the local [CII]-SFR relation

15. Vallini+2015, ApJ accepted Deviation from the local [CII]-SFR relation decreasing metallicity and/or different metallicity profile

16. Vallini+2015, ApJ accepted Deviation from the local [CII]-SFR relation changing the slope in the KS relation

17. log(LCII) = 7.0 + 1.2 × log(SFR) + 0.021 × log(Z) + 0.012 x log(SFR)log(Z) − 0.74 × log 2 (Z) Best fit relation (Yue, Ferrara, Pallottini, Gallerani LV+ 2015): [CII]-SFR relation: best fit

18. Results: [CII] spectrum Vallini+2015, ApJ accepted. [CII] spectrum

19. Conclusions [CII] emission can arise from cold clumps displaced from the center of the LAEs [CII] emission from PDR can be quenched by the feedback of star formation [CII]-SFR relation is expected to hold at high-z: any displacement from the local relation can be due to A) a low metal abundance and/or B) a modified KS relation