MIRI/JWST observations reveal an extremely obscured starburst in the z=6.9 system SPT0311-58
| Autor: | Álvarez-Márquez, J., Gómez, A. Crespo, Colina, L., Neeleman, M., Walter, F., Labiano, A., Pérez-González, P., Bik, A., Noorgaard-Nielsen, H. U., Ostlin, G., Wright, G., Alonso-Herrero, A., Azollini, R., Caputi, K. I., Eckart, A., Fèvre, O. Le, García-Marín, M., Greve, T. R., Hjorth, J., Ilbert, O., Kendrew, S., Pye, J. P., Tikkanen, T., Topinka, M., van der Werf, P., Ward, M., van Dishoeck, E. F., Güdel, M., Henning, Th., Lagage, P. O., Ray, T., Waelkens, C. |
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| Rok vydání: | 2023 |
| Předmět: | |
| Zdroj: | A&A 671, A105 (2023) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/202245400 |
| Popis: | Using MIRI on-board JWST we present mid-infrared sub-arcsec imaging (MIRIM) and spectroscopy (MRS) of the hyperluminous infrared system SPT0311-58 at z=6.9. MIRI observations are compared with existing ALMA far-infrared continuum and [CII]158$\mu$m imaging. Even though the ALMA observations suggests very high star formation rates (SFR) in the eastern (E) and western (W) galaxies of the system, the H$\alpha$ line is not detected. This, together with the detection of the Pa$\alpha$ line, implies very high optical nebular extinction with lower limits of 4.2 (E) and 3.9 mag (W), and even larger 5.6 (E) and 10.0 (W) for SED derived values. The extinction-corrected Pa$\alpha$ SFRs are 383 and 230M$_{\odot}$yr$^{-1}$ for the E and W galaxies, respectively. This represents 50% of the SFRs derived from the [CII]158$\mu$m line and infrared light for the E galaxy and as low as 6% for the W galaxy. The MIRI observations reveal a clumpy stellar structure, with each clump having 3 to 5 $\times$10$^{9}$M$_\mathrm{\odot}$, leading to a total stellar mass of 2.0 and 1.5$\times$10$^{10}$M$_\mathrm{\odot}$ for the E and W galaxies, respectively. The specific SFR in the stellar clumps ranges from 25 to 59Gyr$^{-1}$, which are 3 to 10 times larger than the values measured in galaxies of similar mass at redshifts 6 to 8. The overall gas mass fraction is $M_\mathrm{gas}$/$M_*\sim3$, similar to that of z=4.5-6 star-forming galaxies. The observed properties of SPT0311-58 such as the clumpy distribution at sub(kpc) scales and the very high average extinction are similar to those observed in low- and intermediate-z LIRGs and ULIRGs, even though SPT0311-58 is observed only 800 Myr after the Big Bang. Massive, heavily obscured, clumpy starburst systems like SPT0311-58 likely represent the early phases in the formation of massive high-z bulge/spheroids and luminous quasars. Comment: 18 pages, 8 figures, final published version in A&A |
| Databáze: | arXiv |
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