The MAGPI Survey: Insights into the Lyman-alpha line widths and the size of ionized bubbles at the edge of cosmic reionization
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2024
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| author | Mukherjee, T. Zafar, T. Nanayakkara, T. Gupta, A. Gurung-Lopez, S. Battisti, A. Wisnioski, E. Foster, C. Mendel, J. T. Harborne, K. E. Lagos, C. D. P. Kodama, T. Croom, S. M. Thater, S. Webb, J. Barsanti, S. Sweet, S. M. Prathap, J. Valenzuela, L. M. Mailvaganam, A. Martinez, J. L. Carrillo |
| author_facet | Mukherjee, T. Zafar, T. Nanayakkara, T. Gupta, A. Gurung-Lopez, S. Battisti, A. Wisnioski, E. Foster, C. Mendel, J. T. Harborne, K. E. Lagos, C. D. P. Kodama, T. Croom, S. M. Thater, S. Webb, J. Barsanti, S. Sweet, S. M. Prathap, J. Valenzuela, L. M. Mailvaganam, A. Martinez, J. L. Carrillo |
| contents | We present spectroscopic properties of 22 Lyman-alpha emitters(LAEs) at z=5.5-6.6 with Lyman-alpha(Lya) luminosity log($L_{Lya}$[$ergs^{-1}$])=42.4-43.5, obtained using VLT/MUSE as part of the Middle Ages Galaxy Properties with Integral Field Spectroscopy(MAGPI) survey. Additionally, we incorporate broad-band photometric data from the Subaru Hyper Suprime-Cam(HSC) for 17 LAEs in our sample. The HSC-y band magnitudes show that our LAEs are UV-bright, with rest-frame absolute UV magnitudes -19.7 < $M_{UV}$ < -23.3. We find that the Lya line width increases with luminosity, and this trend becomes more prominent at z > 6 where Lya lines become significantly broadened (> 260 $kms^{-1}$) at luminosities log($L_{Lya}$[$ergs^{-1}$]) > 43. This broadening is consistent with previous studies, suggesting that these sources are located inside larger ionized bubbles. We observe a slightly elevated ionizing photon production efficiency estimated for LAEs at z > 6, indicating that younger galaxies could be producing more ionizing photons per UV luminosity. A tentative anti-correlation between ionizing photon production efficiency and Lya rest-frame equivalent width is noticed, which could indicate a time delay between production and escape of ionizing photon primarily due to supernovae activity. Furthermore, we find a positive correlation between bubble radius and Lya line width, which again suggests that large ionized bubbles are created around these LAEs, allowing them to self-shield from the scattering effects of the intergalactic medium (IGM). We also detect two closely separated LAEs at z=6.046 (projected spatial separation is 15.92 kpc). The size of their respective bubbles suggests that they likely sit inside a common large ionized region. Such a closely-separated LAE pair increases the size of ionized bubble, potentially allowing a boosted transmission of Lya through neutral IGM. (Abridged) |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2410_17684 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | The MAGPI Survey: Insights into the Lyman-alpha line widths and the size of ionized bubbles at the edge of cosmic reionization Mukherjee, T. Zafar, T. Nanayakkara, T. Gupta, A. Gurung-Lopez, S. Battisti, A. Wisnioski, E. Foster, C. Mendel, J. T. Harborne, K. E. Lagos, C. D. P. Kodama, T. Croom, S. M. Thater, S. Webb, J. Barsanti, S. Sweet, S. M. Prathap, J. Valenzuela, L. M. Mailvaganam, A. Martinez, J. L. Carrillo Astrophysics of Galaxies We present spectroscopic properties of 22 Lyman-alpha emitters(LAEs) at z=5.5-6.6 with Lyman-alpha(Lya) luminosity log($L_{Lya}$[$ergs^{-1}$])=42.4-43.5, obtained using VLT/MUSE as part of the Middle Ages Galaxy Properties with Integral Field Spectroscopy(MAGPI) survey. Additionally, we incorporate broad-band photometric data from the Subaru Hyper Suprime-Cam(HSC) for 17 LAEs in our sample. The HSC-y band magnitudes show that our LAEs are UV-bright, with rest-frame absolute UV magnitudes -19.7 < $M_{UV}$ < -23.3. We find that the Lya line width increases with luminosity, and this trend becomes more prominent at z > 6 where Lya lines become significantly broadened (> 260 $kms^{-1}$) at luminosities log($L_{Lya}$[$ergs^{-1}$]) > 43. This broadening is consistent with previous studies, suggesting that these sources are located inside larger ionized bubbles. We observe a slightly elevated ionizing photon production efficiency estimated for LAEs at z > 6, indicating that younger galaxies could be producing more ionizing photons per UV luminosity. A tentative anti-correlation between ionizing photon production efficiency and Lya rest-frame equivalent width is noticed, which could indicate a time delay between production and escape of ionizing photon primarily due to supernovae activity. Furthermore, we find a positive correlation between bubble radius and Lya line width, which again suggests that large ionized bubbles are created around these LAEs, allowing them to self-shield from the scattering effects of the intergalactic medium (IGM). We also detect two closely separated LAEs at z=6.046 (projected spatial separation is 15.92 kpc). The size of their respective bubbles suggests that they likely sit inside a common large ionized region. Such a closely-separated LAE pair increases the size of ionized bubble, potentially allowing a boosted transmission of Lya through neutral IGM. (Abridged) |
| title | The MAGPI Survey: Insights into the Lyman-alpha line widths and the size of ionized bubbles at the edge of cosmic reionization |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2410.17684 |