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Spatially resolved H α and ionizing photon production efficiency in the lensed galaxy MACS1149-JD1 at a redshift of 9.11

2024; EDP Sciences; Volume: 686; Linguagem: Inglês

10.1051/0004-6361/202347946

1432-0746

Javier Álvarez-Márquez, L. Colina, A. Crespo Gómez, Pierluigi Rinaldi, Jens Melinder, G. Östlin, Marianna Annunziatella, Á. Labiano, A. Bik, S. Bosman, T. R. Greve, G. Wright, A. Alonso‐Herrero, Leindert Boogaard, R. Azollini, K. I. Caputi, Luca Costantin, A. Eckart, M. García-Marín, Steven Gillman, J. Hjorth, Edoardo Iani, O. Ilbert, Iris Jermann, Danial Langeroodi, R. A. Meyer, Florian Peißker, Pablo G. Pérez‐González, J. P. Pye, Tuomo Tikkanen, M. Topinka, P. van der Werf, Fabian Walter, Th. Henning, T. P. Ray,

Stellar, planetary, and galactic studies

We present MIRI/JWST medium-resolution spectroscopy (MRS) and imaging (MIRIM) of the lensed galaxy MACS1149-JD1 at a redshift of z = 9.1092 ± 0.0002, when the Universe was about 530 Myr old. We detect, for the first time, spatially resolved H α emission in a galaxy at a redshift above nine. The structure of the H α emitting gas consists of two clumps, S and N, carrying about 60% and 40% of the total flux, respectively. The total H α luminosity implies an instantaneous star-formation rate in the range of 3.2 ± 0.3 and 5.3 ± 0.4 M ⊙ yr −1 for sub-solar and solar metallicities. The ionizing photon production efficiency, log( ζ ion ), shows a spatially resolved structure with values of 25.55 ± 0.03; 25.47 ± 0.03; and 25.91 ± 0.09 Hz erg −1 for the integrated galaxy and clumps S and N, respectively. The H α rest-frame equivalent width, EW 0 (H α ), is 726 −182 +660 Å for the integrated galaxy, but it presents extreme values of 531 −96 +300 Å and ≥1951 Å for clumps S and N, respectively. The spatially resolved ionizing photon production efficiency is within the range of values measured in galaxies at a redshift above six and well above the canonical value (25.2 ± 0.1 Hz erg −1 ). The EW 0 (H α ) is a factor of two lower than the predicted value at z = 9.11 based on the extrapolation of the evolution of the EW 0 (H α ) with redshifts, ∝(1 + z ) 2.1 , including galaxies detected with JWST. The extreme difference of the EW 0 (H α ) for clumps S and N indicates the presence of a recent (< 5 Myr) stellar burst in clump N and a star formation over a larger period of time (e.g., ∼50 Myr) in clump S. The different ages of the stellar population place MACS1149-JD1 and clumps N and S at different locations in the log( ζ ion ) to EW 0 (H α ) plane and above the main relation defined from intermediate- and high-redshift ( z = 3 − 7) galaxies detected with JWST. Finally, clump S and N show very different H α kinematics, with velocity dispersions of 56 ± 4 km s −1 and 113 ± 33 km s −1 , likely indicating the presence of outflows or increased turbulence in clump N. The dynamical mass M dyn = (2.4 ± 0.5) × 10 9 M ⊙ , obtained from the size of the integrated H α ionized nebulae and its velocity dispersion, is within the range previously measured with the spatially resolved [OIII]88 μm line.