Strong Balmer break objects at z ~ 7-10 uncovered with JWST
| Autor: | Kuruvanthodi, A., Schaerer, D., Marques-Chaves, R., Korber, D., Weibel, A., Oesch, P., Roberts-Borsani, G. |
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| Rok vydání: | 2024 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | We report the discovery of robust spectroscopically confirmed Balmer break (BB) galaxies and candidates, with secure spectroscopic redshifts $7.1 \le z \le 9.6$ from publicly available JWST extra-galactic photometric and spectroscopic surveys. To do so, we used dedicated filters probing the Balmer break and inspected the objects with NIRSpec spectroscopy. We recover the previously known objects with strong Balmer breaks and reveal 10-11 new objects with clear BBs, thus tripling the number of spectroscopically confirmed galaxies with a BB at z >7. Approximately half of them show a pure BB and no signs of recent star formation, whereas the other half shows BB and emission lines, indicating most likely galaxies whose star formation ceased earlier and has restarted recently. Overall we find that ~10-20% of all galaxies from our sample show signatures of an evolved stellar population. Furthermore, we find that the strength of the BB does not strongly depend on the rest-optical brightness of these sources. In short, our work confirms that photometry alone has the potential to measure BB strengths and to identify evolved stellar populations at high redshift and that such objects may be more frequent than previously thought. Comment: 6 pages, 4 figures, Submitted to A&A, Comments are welcome |
| Databáze: | arXiv |
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