Escape fractions from unattenuated Ly$α$ emitters around luminous $z>6$ quasars
Fuente:
arXiv
Saved in:
| Main Authors: | , , , , , , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2025
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866915507693682688 |
|---|---|
| author | Yue, Minghao Eilers, Anna-Christina Matthee, Jorryt Naidu, Rohan P. Bordoloi, Rongmon Davies, Frederick B. Hennawi, Joseph F. Kashino, Daichi Mackenzie, Ruari Simcoe, Robert A. |
| author_facet | Yue, Minghao Eilers, Anna-Christina Matthee, Jorryt Naidu, Rohan P. Bordoloi, Rongmon Davies, Frederick B. Hennawi, Joseph F. Kashino, Daichi Mackenzie, Ruari Simcoe, Robert A. |
| contents | Ionized proximity zones around luminous quasars provide a unique laboratory to characterize the Ly$α$ emission lines from $z>6$ galaxies without significant attenuation from the intergalactic medium (IGM). However, Ly$α$ line measurements for galaxies within high-redshift quasars' proximity zones have been rare so far. Here we present deep spectroscopic observations obtained with the NIRSpec/MSA instrument on the James Webb Space Telescope (JWST) of galaxies in two $z>6$ quasar fields. We measure the Ly$α$ line fluxes for 50 galaxies at $6<z<7$ with UV absolute magnitude $M_\text{UV}<-19$ (median $M_\text{UV}=-19.97$), among which 15 are located near the luminous quasars, i.e. within $Δv<2500\rm\,km\,s^{-1}$. We find that galaxies near the quasars show significant flux bluewards of the systemic Ly$α$ wavelength, and have higher Ly$α$ equivalent width compared to galaxies at similar redshifts that are not located within the quasars' environment. Our result indicates little or no redshift evolution for the Ly$α$-emitter fraction from $z\sim6.4$ to $z\sim5$. Leveraging the low IGM opacity in the quasars' vicinity, we evaluate the Ly$α$ escape fraction ($f_\text{esc}^{\text{Ly}α}$) of high-redshift galaxies. Our analysis suggests that galaxies at $\langle z\rangle\approx6.4$ have an average $f_\text{esc}^{\text{Ly}α}=0.14\pm0.04$. This value is consistent with reionization models where the Lyman continuum escape fraction is low $(f_\text{esc}^\text{LyC}\lesssim0.1)$ for luminous galaxies, and where the most luminous galaxies have only a minor contribution to the total ionizing photon budget. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2507_05381 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Escape fractions from unattenuated Ly$α$ emitters around luminous $z>6$ quasars Yue, Minghao Eilers, Anna-Christina Matthee, Jorryt Naidu, Rohan P. Bordoloi, Rongmon Davies, Frederick B. Hennawi, Joseph F. Kashino, Daichi Mackenzie, Ruari Simcoe, Robert A. Astrophysics of Galaxies Ionized proximity zones around luminous quasars provide a unique laboratory to characterize the Ly$α$ emission lines from $z>6$ galaxies without significant attenuation from the intergalactic medium (IGM). However, Ly$α$ line measurements for galaxies within high-redshift quasars' proximity zones have been rare so far. Here we present deep spectroscopic observations obtained with the NIRSpec/MSA instrument on the James Webb Space Telescope (JWST) of galaxies in two $z>6$ quasar fields. We measure the Ly$α$ line fluxes for 50 galaxies at $6<z<7$ with UV absolute magnitude $M_\text{UV}<-19$ (median $M_\text{UV}=-19.97$), among which 15 are located near the luminous quasars, i.e. within $Δv<2500\rm\,km\,s^{-1}$. We find that galaxies near the quasars show significant flux bluewards of the systemic Ly$α$ wavelength, and have higher Ly$α$ equivalent width compared to galaxies at similar redshifts that are not located within the quasars' environment. Our result indicates little or no redshift evolution for the Ly$α$-emitter fraction from $z\sim6.4$ to $z\sim5$. Leveraging the low IGM opacity in the quasars' vicinity, we evaluate the Ly$α$ escape fraction ($f_\text{esc}^{\text{Ly}α}$) of high-redshift galaxies. Our analysis suggests that galaxies at $\langle z\rangle\approx6.4$ have an average $f_\text{esc}^{\text{Ly}α}=0.14\pm0.04$. This value is consistent with reionization models where the Lyman continuum escape fraction is low $(f_\text{esc}^\text{LyC}\lesssim0.1)$ for luminous galaxies, and where the most luminous galaxies have only a minor contribution to the total ionizing photon budget. |
| title | Escape fractions from unattenuated Ly$α$ emitters around luminous $z>6$ quasars |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2507.05381 |