Constraining the physical properties of high-redshift star-forming galaxies with MUSE and ALMA

The main purpose of this Master Degree Thesis has been the measurement of physical parameters, i.e. the stellar mass content (M?), the Star Formation Rate (SFR) and the extinction (AV), for a sample of distant dusty galaxies selected with ALMA, i.e. the Atacama Large Millimeter/submillimeter Array, in the Hubble Ultra Deep Field (HUDF, Beckwith et al. 2003). The sources were chosen among the galaxies presented in a recent paper by Dunlop et al. (2016) and their physical parameters, subjects of our study, were retrieved by means of an advanced modeling analysis which combines the high-resolution spectroscopy from MUSE instrument (i.e. the Multi-Unit Spectroscopic Explorer) and a multi-wavelength photometry. To this aim, we referred to the photometric catalog presented by Santini et al. (2009), an updated version of the multicolour GOODS-MUSIC catalog (i.e. GOODS MUlitcolour Southern Infrared Catalog, Grazian et al. 2006). The software adopted for this task has been the spectro-photometric fitting code SINOPSIS by Fritz et al. (2007). Concurrently to the study on the ALMA-detected sources, we performed a statistical analysis on a comparison sample of unobscured star-forming galaxies selected from the HST catalog by Coe et al. (2006), on the basis of well-defined criteria. We limited the comparison sample to galaxies within the deepest pointing of the MUSE HUDF survey (Program ID 094.A-0289, P.I. Bacon; paper in prep.), in the photometric redshift range 0.5 < z < 0.8, where MUSE optical spectra provide a direct measure of [OII] emission lines, and to sources with a detection in the H band. This last demand allowed to restrict our analysis to a well controlled sample, where the near-IR detection guarantees the measurements of secure stellar masses. To compare the results obtained by means of SINOPSIS to what is attainable with a classical photometric SED-fitting approach, we resort to HyperZmass (Pozzetti et al., 2007). This procedure gave us the opportunity to investigate the potential improvements in the measurements of the physical parametrs of distant galaxies due to the inclusion of high-resolution spectral information (in particular emission lines) in SED fitting procedures. In fact, even if looking at the larger comparison sample of normal star-forming galaxies, we found that the two codes provide consistent results, within the range of allowed parameters (in particular the SF histories). Our results show that a spectro-photometric code (SINOPSIS), accounting for the presence of emission lines and combined to broad-band optical/near-IR photometry, returns very high extinctions for the dusty sources selected in the millimeter continuum. Indeed, the ALMA sources resulted to be the most obscured and star-forming objects of the sample. Such level of obscuration is not recovered by a standard SED fitting approach (e.g. HyperZmass), neglecting the presence of emission lines. The AV derived from SINOPSIS for this starbursting source also exceeds the AIRX computed including Herschel photometry, but the large formal uncertainties on this parameter for this source do not provide a conclusive result. Concluding, our work highlighted how the combination of ALMA and MUSE, two state-of-the-art instruments working in completely different spectral ranges (millimeter and optical), provides an important test on the potential scientific exploitation of the large data-sets that are becoming publicly available to the community (through the respective data archives).