# MIDIS. JWST NIRCam and MIRI unveil the stellar population properties of Ly$α$-emitters and Lyman-Break galaxies at z ~ 3-7

**Authors:** 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  
**arXiv:** [2309.08515](https://arxiv.org/abs/2309.08515)  
**Date:** 2023-09-15  
**Summary page:** https://www.summarizepaper.com/en/paper/2309.08515v1/

## Key points

- Investigated stellar population properties of Lyman-alpha emitters (LAEs) and Lyman-Break galaxies (LBGs) at redshifts 2.8 to 6.7 in the Hubble eXtreme Deep Field (XDF)
- Analyzed a sample of 182 spectroscopically-confirmed LAEs observed with MUSE/VLT and 450 photometrically-selected LBGs
- Examined rest-frame UV-through-near-IR spectral energy distributions (SEDs) using HST and JWST NIRCam and MIRI observations
- LAEs in the sample are low-mass objects with median stellar mass of log$_{10}$(M$_\star$[M$_\odot$]) ~ 7.5
- LAEs exhibit little to no dust extinction, average E(B - V) value ~0.1, and have a blue UV continuum slope ($\beta$ ~ -2.2)
- Majority (75%) of LAEs are young with ages less than 100 million years, while remaining 25% have older stellar populations exceeding 100 million years
- Older LAEs tend to be more massive, less extinct, and have lower specific star formation rates compared to younger counterparts
- No significant statistical differences found between properties of LAEs and a stellar-mass matched sample of LBGs except for slightly redder UV continuum slopes and marginally larger E(B - V) values in LBGs
- Nearly half (48%) of starburst LBGs lack detectable Lyman-alpha emission due to HI resonant scattering or selective dust extinction effects
- JWST observations play crucial role in determining properties of LAEs and comparing them to LBGs
- Study provides valuable insights into high redshift galaxy's stellar population properties by utilizing multiwavelength observations

## Summary

In this study, the authors investigate the stellar population properties of Lyman-alpha emitters (LAEs) and Lyman-Break galaxies (LBGs) at redshifts ranging from 2.8 to 6.7 in the Hubble eXtreme Deep Field (XDF). They analyze a sample of 182 spectroscopically-confirmed LAEs observed with MUSE/VLT and 450 photometrically-selected LBGs. Leveraging the combined power of HST and JWST NIRCam and MIRI observations, they examine their rest-frame UV-through-near-IR spectral energy distributions (SEDs), with a particular focus on the role of MIRI in assessing the stellar mass and ages of LAEs. The results reveal that the LAEs in this sample are low-mass objects, with a median stellar mass of log$_{10}$(M$_\star$[M$_\odot$]) ~ 7.5. They exhibit little to no dust extinction, with an average E(B - V) value of ~0.1, and have a blue UV continuum slope ($\beta$ ~ -2.2). The majority (75%) of these LAEs are young, with ages less than 100 million years, while the remaining 25% have significantly older stellar populations exceeding 100 million years. The older LAEs tend to be more massive, less extinct, and have lower specific star formation rates compared to their younger counterparts. When comparing the properties of LAEs to those of a stellar-mass matched sample of LBGs, no significant statistical differences are found between these two populations except for slightly redder UV continuum slopes and marginally larger E(B - V) values in LBGs. Additionally, nearly half (48%) of the LBGs classified as starbursts based on their ages (< 10 million years) lack detectable Lyman-alpha emission due to HI resonant scattering and/or selective dust extinction effects. The authors emphasize the crucial role that JWST observations play in determining the properties of LAEs and shedding light on similarities or differences between them and LBGs. This study provides valuable insights into high redshift galaxy's stellar population properties by highlighting how multiwavelength observations can help us understand their formation and evolution processes better.