Séminaire/Seminar Galaxies |
| « Spectroscopic insights into the cosmic dark ages with JWST » |
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Guido Roberts-Borsani |
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James Webb Space Telescope (JWST) has already revolutionized our picture of the high redshift Universe by revealing a new population of luminous galaxies out to z~12-13. While these breakthroughs are no doubt transformative, each of these remain candidates until they pass the ultimate test of spectroscopic verification and characterization.
As such, in this talk I will summarize the first high redshift spectroscopic efforts from the GLASS-JWST ERS survey, using NIRISS and NIRSpec spectroscopy. Among these, I'll showcase the power of JWST to peer deep into Reionization, when most intergalactic hydrogen is neutral, by spectroscopically confirming two lensed galaxies via their clear Lyman Breaks with NIRISS, placing them at redshifts of z~8. The absence of strong emission line indicators (e.g., Lya, NV, HeII), blue UV slopes and moderate absolute magnitudes (MUV ~ -20 AB) suggest these objects are young, dust-poor, and representative of a general z~8 population that has thus far been missed. Further follow up with NIRSpec of them and several nearby z~8 candidates confirm their presence via strong emission lines as part of a larger protocluster of at least 7 galaxies, only ~650 Myrs after the Big Bang. Finally, I'll present the spectro-photometric confirmation and characterization with NIRSpec of a lensed and triply-imaged galaxy at z=9.793, placing it deep in the heart of the cosmic Dark Ages. With an absolute magnitude of MUV ~ -17.35 AB, the object is the faintest known source at comparable redshifts and likely representative of the faint populations of galaxies that represent the primary drivers of the reionization process. |
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jeudi 23 mars 2023 - 11:30 Amphithéâtre Henri Mineur Institut d'Astrophysique de Paris |
| Page web du séminaire / Seminar's webpage |