Résumé / Abstract Seminaire_IAP
« Dusty galaxies and their gas reservoirs in the high-z Universe as seen by the ALPINE survey »

Matthieu Bethermin
Lab. Astroph. Marseille (LAM) (Marseille, France)

Understanding the physical mechanisms leading to the early formation of intermediate and massive galaxies in the first two billions of years of the Universe remains a challenge for astrophysics. In particular, we expect star formation processes to differ from the local Universe. The unprecedented ALMA capabilities allow us to trace the gas reservoirs fueling their star formation and the interstellar dust, which indirectly traces the metal enrichment, but also hides a significant fraction of the star formation from optical telescopes.

The ALPINE survey is an ALMA large program, which has built the first statistical sample of normal star-forming galaxies at z>4 by targeting emission from singly ionized carbon [CII] at 158 µm and the thermal continuum from dust at the end of the epoch of reionization (4.4 < z < 5.9). The ALPINE observations have revealed that a significant fraction of the star formation at this epoch is already hidden by dust clouds, in particular in the most massive systems.

ALPINE is also a fantastic opportunity to study the [CII] 158 microns line at this early epoch, one of the brightest lines emitted by galaxies (up to 0.3% of the total bolometric energy). We found that its luminosity follows the same relation with the star formation rate as in the local Universe, which is surprising considering the lower expected metallicity. In addition, we found evidence of outflows and extended [CII]-emitting halos around the most star-forming systems, which are clues of an early enrichment of the circum galactic medium. Finally, for the brightest objects, we can study the dynamics of the ALPINE systems, revealing a mix of major mergers, rotators, and dispersion dominated systems.
vendredi 13 novembre 2020 - 11:00
Webinaire, Institut d'Astrophysique de Paris
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