MIDIS: JWST NIRCam and MIRI unveil the stellar population properties of Ly$\alpha$-emitters and Lyman-Break galaxies at z ~ 3-7

Edoardo Iani; Karina I. Caputi; Pierluigi Rinaldi; Marianna Annunziatella; Leindert A. Boogaard; Göran Östlin; Luca Costantin; Steven Gillman; Pablo G. Pérez-González; Luis Colina; Gillian Wright; Almudena Alonso-Herrero; Javier Álvarez-Márquez; Arjan Bik; Sarah E. I. Bosman; Alejandro Crespo-Gómez; Andreas Eckart; Thomas R. Greve; Thomas K. Henning; Jens Hjorth; Iris Jermann; Alvaro Labiano; Danial Langeroodi; Jens Melinder; Thibaud Moutard; Florian Peissker; John P. Pye; Tuomo V. Tikkanen; Paul P. van der Werf; Fabian Walter; Pierre-Olivier Lagage; Ewine F. van Dishoeck

arXiv · 2309.08515

MIDIS: JWST NIRCam and MIRI unveil the stellar population properties of Ly$\alpha$-emitters and Lyman-Break galaxies at z ~ 3-7

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Abstract

We study the stellar population properties of 182 spectroscopically-confirmed (MUSE/VLT) Lyman-$\alpha$ emitters (LAEs) and 450 photometrically-selected Lyman-Break galaxies (LBGs) at z = 2.8 - 6.7 in the Hubble eXtreme Deep Field (XDF). Leveraging the combined power of HST and JWST NIRCam and MIRI observations, we analyse their rest-frame UV-through-near-IR spectral energy distributions (SEDs) with MIRI playing a crucial role in robustly assessing the LAE's stellar mass and ages. Our LAEs are low-mass objects (log$_{10}$(M$_\star$[M$_\odot$]) ~ 7.5), with little or no dust extinction (E(B - V) ~ 0.1) and a blue UV continuum slope ($\beta$ ~ -2.2). While 75% of our LAEs are young (< 100 Myr), the remaining 25% have significantly older stellar populations (> 100 Myr). These old LAEs are statistically more massive, less extinct and have lower specific star formation rate (sSFR) compared to young LAEs. Besides, they populate the M$_\star$ - SFR plane along the main-sequence (MS) of star-forming galaxies, while young LAEs populate the starburst region. The comparison between the LAEs properties to those of a stellar-mass matched sample of LBGs shows no statistical difference between these objects, except for the LBGs redder UV continuum slope and marginally larger E(B - V) values. Interestingly, 48% of the LBGs have ages < 10 Myr and are classified as starbursts, but lack detectable Ly$\alpha$ emission. This is likely due to HI resonant scattering and/or selective dust extinction. Overall, we find that JWST observations are crucial in determining the properties of LAEs and shedding light on the properties and similarities between LAEs and LBGs.

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Edoardo Iani, Karina I. Caputi, Pierluigi Rinaldi, Marianna Annunziatella, Leindert A. Boogaard, Göran Östlin, Luca Costantin, Steven Gillman, Pablo G. Pérez-González, Luis Colina, Gillian Wright, Almudena Alonso-Herrero, Javier Álvarez-Márquez, Arjan Bik, Sarah E. I. Bosman, Alejandro Crespo-Gómez, Andreas Eckart, Thomas R. Greve, Thomas K. Henning, Jens Hjorth, Iris Jermann, Alvaro Labiano, Danial Langeroodi, Jens Melinder, Thibaud Moutard, Florian Peissker, John P. Pye, Tuomo V. Tikkanen, Paul P. van der Werf, Fabian Walter, Pierre-Olivier Lagage, Ewine F. van Dishoeck. 2023-09-15. MIDIS: JWST NIRCam and MIRI unveil the stellar population properties of Ly$\alpha$-emitters and Lyman-Break galaxies at z ~ 3-7. https://arxiv.org/abs/2309.08515

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