Spatially resolved H$α$ emission in B14-65666: compact starbursts, ionizing efficiency and gas kinematics in an advanced merger at the Epoch of Reionization
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| Format: | Preprint |
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2025
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| author | Prieto-Jiménez, C. Álvarez-Márquez, J. Colina, L. Gómez, A. Crespo Bik, A. Östlin, G. Alonso-Herrero, A. Boogaard, L. Caputi, K. I. Costantin, L. Eckart, A. García-Marín, M. Gillman, S. Hjorth, J. Iani, E. Jermann, I. Labiano, A. Langeroodi, D. Melinder, J. Moutard, T. Peißker, F. Pérez-González, P. G. Pye, J. P. Rinaldi, P. Tikkanen, T. V. van der Werf, P. Walter, F. Hashimoto, T. Sugahara, Y. Güdel, M. Henning, T. |
| author_facet | Prieto-Jiménez, C. Álvarez-Márquez, J. Colina, L. Gómez, A. Crespo Bik, A. Östlin, G. Alonso-Herrero, A. Boogaard, L. Caputi, K. I. Costantin, L. Eckart, A. García-Marín, M. Gillman, S. Hjorth, J. Iani, E. Jermann, I. Labiano, A. Langeroodi, D. Melinder, J. Moutard, T. Peißker, F. Pérez-González, P. G. Pye, J. P. Rinaldi, P. Tikkanen, T. V. van der Werf, P. Walter, F. Hashimoto, T. Sugahara, Y. Güdel, M. Henning, T. |
| contents | We present MIRI/JWST medium resolution spectroscopy (MRS) and imaging (MIRIM) of B14-65666, a Lyman-break and interacting galaxy at redshift $z$=7.15. We detect the H$α$ line emission in this system, revealing a spatially-resolved structure of the H$α$ emitting gas, which consists of two distinct galaxies, E and W, at a projected distance of 0.4". Galaxy E is very compact in the rest-frame UV, while W galaxy is more extended, showing a clumpy structure reminiscent of a tidal tail. The total H$α$ luminosity implies that the system is forming stars at a Star Formation Rate (SFR) of 76$\pm$8 M$_{\odot}$ yr$^{-1}$ and 30$\pm$4 M$_{\odot}$ yr$^{-1}$ for E and W, respectively. The ionizing photon production efficiency is within the range measured in galaxies at similar redshifts. The high values derived for the H$α$ equivalent widths (EW) and the distinct locations of the E and W galaxies in the $\log(ζ_\mathrm{ion}$) $-$ EW (H$α$) plane, indicate that the system is dominated by a young (less than 10 Myr) stellar population. The overall spectral energy distribution suggests that in addition to a young stellar population, the two galaxies may have mature stellar population and very different dust attenuation. The derived SFR and stellar masses identify the two galaxies as going through a starburst phase. The kinematics of the ionized gas traced by the H$α$ line show a velocity difference of 175 $\pm$ 28 km s$^{-1}$ between the two components of B14-65666. The in-depth study of systems like B14-65666 reveal how galaxy mergers in the early Universe drive intense star formation, shape the interstellar medium, and influence the buildup of stellar mass, just 700 $-$ 800 Myr after the Big Bang. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_06793 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Spatially resolved H$α$ emission in B14-65666: compact starbursts, ionizing efficiency and gas kinematics in an advanced merger at the Epoch of Reionization Prieto-Jiménez, C. Álvarez-Márquez, J. Colina, L. Gómez, A. Crespo Bik, A. Östlin, G. Alonso-Herrero, A. Boogaard, L. Caputi, K. I. Costantin, L. Eckart, A. García-Marín, M. Gillman, S. Hjorth, J. Iani, E. Jermann, I. Labiano, A. Langeroodi, D. Melinder, J. Moutard, T. Peißker, F. Pérez-González, P. G. Pye, J. P. Rinaldi, P. Tikkanen, T. V. van der Werf, P. Walter, F. Hashimoto, T. Sugahara, Y. Güdel, M. Henning, T. Astrophysics of Galaxies We present MIRI/JWST medium resolution spectroscopy (MRS) and imaging (MIRIM) of B14-65666, a Lyman-break and interacting galaxy at redshift $z$=7.15. We detect the H$α$ line emission in this system, revealing a spatially-resolved structure of the H$α$ emitting gas, which consists of two distinct galaxies, E and W, at a projected distance of 0.4". Galaxy E is very compact in the rest-frame UV, while W galaxy is more extended, showing a clumpy structure reminiscent of a tidal tail. The total H$α$ luminosity implies that the system is forming stars at a Star Formation Rate (SFR) of 76$\pm$8 M$_{\odot}$ yr$^{-1}$ and 30$\pm$4 M$_{\odot}$ yr$^{-1}$ for E and W, respectively. The ionizing photon production efficiency is within the range measured in galaxies at similar redshifts. The high values derived for the H$α$ equivalent widths (EW) and the distinct locations of the E and W galaxies in the $\log(ζ_\mathrm{ion}$) $-$ EW (H$α$) plane, indicate that the system is dominated by a young (less than 10 Myr) stellar population. The overall spectral energy distribution suggests that in addition to a young stellar population, the two galaxies may have mature stellar population and very different dust attenuation. The derived SFR and stellar masses identify the two galaxies as going through a starburst phase. The kinematics of the ionized gas traced by the H$α$ line show a velocity difference of 175 $\pm$ 28 km s$^{-1}$ between the two components of B14-65666. The in-depth study of systems like B14-65666 reveal how galaxy mergers in the early Universe drive intense star formation, shape the interstellar medium, and influence the buildup of stellar mass, just 700 $-$ 800 Myr after the Big Bang. |
| title | Spatially resolved H$α$ emission in B14-65666: compact starbursts, ionizing efficiency and gas kinematics in an advanced merger at the Epoch of Reionization |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2507.06793 |