Blind line search in ALMA deep fields as pathfinders for future synergies with ngVLA, JWST, SPICA

The results of a blind search for emission lines in several ALMA datacubes at different depths - undertaken with the aim to construct a luminosity function of the FIR ([CII], [OIII]) and molecular lines at various redshifts - will be presented and discussed with a look at their role as reference for future ground-based and space mission at longer (ngVLA) and shorter (JWST and SPICA) wavelengths. We have used a few different - both empirical and statistical - methods to extract sources with a high level of reliability. The main target of this project are the FIR lines which are responsible for the cooling of the interstellar medium (ISM) and which are directly connected to the star formation processes in galaxies. The individual study of these lines allows to investigate also the physical properties of the ISM. For instance, the [CII] 158 μm line mainly arises from cold neutral gas heated by massive stars and the [OIII] 88 μm line arises only from ionised gas. The [CII]/[OIII] luminosity ratio shows a transition from above unity at z = 0 to less at z ≥ 7 indicating that targeting [CII] and [OIII] lines will enable us to study the transition of properties of the ISM at various redshifts. However any other line (for instance various CO transition, water) may be identified with our methods. Once consolidated the physical properties of the high-z sources blindly discovered will constitute a database which will be used both as follow-up and synergies at longer and shorter wavelengths. The exploitation of their characteristics allows similar searches at larger redshift with ngVLA and at the same time studying their counterpart at mid- and far-IR with JSWT and SPICA.