MIDIS: JWST NIRCam and MIRI Unveil the Stellar Population Properties of Lyα Emitters and Lyman-break Galaxies at z ≃ 3–7
Pérez-González, Pablo G.; Costantin, Luca; Boogaard, Leindert A.; Langeroodi, Danial; Östlin, Göran; Melinder, Jens; Colina, Luis; Rinaldi, Pierluigi; Annunziatella, Marianna; Greve, Thomas R.; Wright, Gillian; Alonso-Herrero, Almudena; Álvarez-Márquez, Javier; Caputi, Karina I.; Eckart, Andreas; Hjorth, Jens; Pye, John P.; Walter, Fabian; Bik, Arjan; Bosman, Sarah E. I.; Gillman, Steven; Iani, Edoardo; Jermann, Iris; Moutard, Thibaud; Lagage, Pierre-Olivier; van Dishoeck, Ewine F.; Henning, Thomas K.; van der Werf, Paul P.; Peißker, Florian; Labiano, Alvaro; Crespo Gómez, Alejandro; Tikkanen, Tuomo V.
Netherlands, Denmark, Spain, Italy, Germany, Sweden, United Kingdom, France, United States
Abstract
We study the stellar population properties of 182 spectroscopically confirmed (MUSE/VLT) Lyα emitters (LAEs) and 450 photometrically selected Lyman-break galaxies (LBGs) at z = 2.8–6.7 in the Hubble Extreme Deep Field. Leveraging the combined power of Hubble Space Telescope and JWST NIRCam and MIRI observations, we analyze their rest-frame UV-through-near-IR spectral energy distributions, with MIRI playing a crucial role in robustly assessing the LAEs' stellar masses and ages. Our LAEs are low-mass objects $({{\rm{log}}}_{10}({M}_{\star }/{M}_{\odot })\simeq 7.5)$ with little or no dust extinction (E(B ‑ V) ≃ 0.1) and a blue UV continuum slope (β ≃ ‑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 than young LAEs. Besides, they populate the plane of M ⋆ versus star formation rate along the main sequence of star-forming galaxies, while young LAEs populate the starburst region. The comparison between the LAEs' properties and 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 Lyα emission. This is likely due to H I resonant scattering and/or dust-selective extinction. Overall, we find that JWST observations are crucial in determining the properties of LAEs and shedding light on their comparison with LBGs.