Séminaire/Seminar Galaxies |
| « Origin of Super-Bright Galaxies at Cosmic Dawn by Feedback-Free Starbursts » |
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Avishai Dekel |
| Observations with the James Web Space Telescope (JWST) indicate a surprising excess of bright galaxies during the first 500 million years of the Universe. This is consistent with highly efficient conversion to stars of the gas accreted onto these galaxies, unlike the strong suppression of star formation by stellar feedback at later times. I will show that the high densities and low metallicities at this early epoch guarantee a high efficiency of star formation in the most massive dark-matter halos. Feedback-free starbursts (FFBs) occur when the free-fall collapse time is shorter than ~1Myr, below the time it takes the low-metallicity massive stars to develop destructive stellar winds and supernovae. This corresponds to a characteristic density of ~3000 atoms per cc. The FFBs gradually turn all the accreted gas into stars in thousands of clusters of ~million solar mass each, which are insensitive to radiative feedback and are shielded against feedback from earlier stars. This scenario has clear predictions for future JWST observations, and interesting implications on the process of cosmological re-ionization, the growth of intermediate-mass black holes, and the formation of globular clusters. |
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jeudi 15 juin 2023 - 11:30 Salle des séminaires Évry Schatzman Institut d'Astrophysique de Paris |
| Page web du séminaire / Seminar's webpage |