Resolving dust and Lyα emission in a lensed galaxy at the epoch of reionization with JWST/CANUCS
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| Main Authors: | , , , , , , , , , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2025
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| author | Markov, V. Bradač, M. Estrada-Carpenter, V. Desprez, G. Rihtaršič, G. Judež, J. Tripodi, R. Sawicki, M. Noirot, G. Martis, N. Willott, C. Abraham, R. Asada, Y. Brammer, G. Matharu, J. Muzzin, A. Sarrouh, G. T. E. Withers, S. Ferrara, A. Fujimoto, S. Gallerani, S. Goovaerts, I. Harshan, A. |
| author_facet | Markov, V. Bradač, M. Estrada-Carpenter, V. Desprez, G. Rihtaršič, G. Judež, J. Tripodi, R. Sawicki, M. Noirot, G. Martis, N. Willott, C. Abraham, R. Asada, Y. Brammer, G. Matharu, J. Muzzin, A. Sarrouh, G. T. E. Withers, S. Ferrara, A. Fujimoto, S. Gallerani, S. Goovaerts, I. Harshan, A. |
| contents | Lyman $α$ emission is highly sensitive to dust and neutral hydrogen and is therefore expected to be strongly suppressed in dusty or gas-rich galaxies during the epoch of reionization (EoR). Nevertheless, numerous moderately dusty Ly$α$ emitters (LAEs) are observed at this epoch, suggesting that complex interstellar medium (ISM) geometries and feedback-driven outflows may facilitate Ly$α$ escape. We investigate the dust, gas, and stellar properties of the gravitationally lensed LAE HCM 6A at $z=6.5676$ to characterize its multiphase ISM and the physical conditions regulating Ly$α$ escape. We combine JWST/NIRISS slitless spectroscopy, HST+JWST/NIRCam imaging, and JWST/NIRSpec slit spectra from the CANUCS program. Using a customized BAGPIPES SED-fitting framework with a flexible attenuation law, we derive stellar, nebular, and dust properties on integrated ($\sim$kpc), slit-level ($\sim$0.1 kpc), and pixel-level ($\sim$25 pc) scales, enabled by strong lensing ($μ\approx 8.3$-$9.1$). A Ly$α$ map from SLEUTH traces the spatial distribution of Ly$α$ emission. We measure an unlensed stellar mass of $\log M_\ast = 8.3$-$8.4$ and an intrinsic UV magnitude of $M_{\rm UV} = -19.8 \pm 0.1$. The older region (S1) is moderately dusty with consistent stellar and nebular attenuation indicators, implying a uniform ISM geometry, while the youngest region (S3) shows strong discrepancies among dust tracers, indicating a feedback-shaped multiphase ISM. Ly$α$ emission arises primarily from S3, where a dust-cleared central clump enables efficient Ly$α$ escape. We find Calzetti-like attenuation curves with a UV bump that strengthens with stellar age and decreasing $A_V$. Our observations provide a uniquely detailed, spatially resolved view of a moderately dusty LAE during the EoR, demonstrating how feedback and multiphase ISM structure govern Ly$α$ escape. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2512_13778 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Resolving dust and Lyα emission in a lensed galaxy at the epoch of reionization with JWST/CANUCS Markov, V. Bradač, M. Estrada-Carpenter, V. Desprez, G. Rihtaršič, G. Judež, J. Tripodi, R. Sawicki, M. Noirot, G. Martis, N. Willott, C. Abraham, R. Asada, Y. Brammer, G. Matharu, J. Muzzin, A. Sarrouh, G. T. E. Withers, S. Ferrara, A. Fujimoto, S. Gallerani, S. Goovaerts, I. Harshan, A. Astrophysics of Galaxies Lyman $α$ emission is highly sensitive to dust and neutral hydrogen and is therefore expected to be strongly suppressed in dusty or gas-rich galaxies during the epoch of reionization (EoR). Nevertheless, numerous moderately dusty Ly$α$ emitters (LAEs) are observed at this epoch, suggesting that complex interstellar medium (ISM) geometries and feedback-driven outflows may facilitate Ly$α$ escape. We investigate the dust, gas, and stellar properties of the gravitationally lensed LAE HCM 6A at $z=6.5676$ to characterize its multiphase ISM and the physical conditions regulating Ly$α$ escape. We combine JWST/NIRISS slitless spectroscopy, HST+JWST/NIRCam imaging, and JWST/NIRSpec slit spectra from the CANUCS program. Using a customized BAGPIPES SED-fitting framework with a flexible attenuation law, we derive stellar, nebular, and dust properties on integrated ($\sim$kpc), slit-level ($\sim$0.1 kpc), and pixel-level ($\sim$25 pc) scales, enabled by strong lensing ($μ\approx 8.3$-$9.1$). A Ly$α$ map from SLEUTH traces the spatial distribution of Ly$α$ emission. We measure an unlensed stellar mass of $\log M_\ast = 8.3$-$8.4$ and an intrinsic UV magnitude of $M_{\rm UV} = -19.8 \pm 0.1$. The older region (S1) is moderately dusty with consistent stellar and nebular attenuation indicators, implying a uniform ISM geometry, while the youngest region (S3) shows strong discrepancies among dust tracers, indicating a feedback-shaped multiphase ISM. Ly$α$ emission arises primarily from S3, where a dust-cleared central clump enables efficient Ly$α$ escape. We find Calzetti-like attenuation curves with a UV bump that strengthens with stellar age and decreasing $A_V$. Our observations provide a uniquely detailed, spatially resolved view of a moderately dusty LAE during the EoR, demonstrating how feedback and multiphase ISM structure govern Ly$α$ escape. |
| title | Resolving dust and Lyα emission in a lensed galaxy at the epoch of reionization with JWST/CANUCS |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2512.13778 |