A unique window into the Epoch of Reionisation: A double-peaked Lyman-$α$ emitter in the proximity zone of a quasar at $z\sim 6.6$
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| Main Authors: | , , , , , , , , , , , , , , |
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| Format: | Preprint |
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2024
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| author | Protušová, Klaudia Bosman, Sarah E. I. Wang, Feige Meyer, Romain A. Champagne, Jaclyn B. Davies, Frederick B. Eilers, Anna-Christina Fan, Xiaohui Hennawi, Joseph F. Jin, Xiangyu Jun, Hyunsung D. Kakiichi, Koki Li, Zihao Liu, Weizhe Yang, Jinyi |
| author_facet | Protušová, Klaudia Bosman, Sarah E. I. Wang, Feige Meyer, Romain A. Champagne, Jaclyn B. Davies, Frederick B. Eilers, Anna-Christina Fan, Xiaohui Hennawi, Joseph F. Jin, Xiangyu Jun, Hyunsung D. Kakiichi, Koki Li, Zihao Liu, Weizhe Yang, Jinyi |
| contents | We present a study of a double-peaked Ly$α$ emitter, named LAE-11, found in the proximity zone of QSO J0910-0414 at $z\sim6.6$. We use a combination of deep photometric data from Subaru Telescope, HST, and JWST with spectroscopic data from Keck/DEIMOS, NIRCam WFSS and NIRSpec MSA to characterise the ionising and general properties of the galaxy, as well as the quasar environment surrounding it. We detect Ly$α$, H$β$, [OIII] doublet, and H$α$ emission lines in the various spectral datasets. The presence of a double-peaked Ly$α$ line in the spectrum allows us to characterise the opening angle and lifetime of the QSO as $θ_Q>49.62$° and $t_Q > 3.8\times10^5$ years. LAE-11 is a fairly bright (M$_\rm{UV} = -19.84^{+0.14}_{-0.16}$), blue galaxy with a UV slope of $β= -2.61^{+0.06}_{-0.08}$. Since the galaxy is located in a quasar-ionised region, we have a unique opportunity to measure the escape fraction of Lyman Continuum photons using the un-attenuated double-peaked Ly$α$ emission profile and its equivalent width at such high redshift. We employ diagnostics which do not rely on the detection of Ly$α$ for comparison, and find that all tracers of ionising photon leakage agree within 1$σ$ uncertainty. We measure a moderate escape of Lyman Continuum photons from LAE-11 of $f_\rm{esc}^\rm{LyC} = (8 - 33)\%$. Detections of both H$α$ and H$β$ emission lines allow for separate measurements of the ionising photon production efficiency, resulting with $\log(ξ_\rm{ion}/\rm{Hz~erg^{-1}}) = 25.59\pm0.08$ and $25.65\pm0.09$, for H$α$ and H$β$, respectively. The total ionising output of LAE-11, $\log(f_\rm{esc}^\rm{LyC}ξ_\rm{ion, Hα}/\rm{Hz~erg^{-1}}) = 24.85^{+0.24}_{-0.34}$, is higher than the value of $24.3 - 24.8$ which is traditionally assumed as needed to drive Reionisation forward. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2412_12256 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | A unique window into the Epoch of Reionisation: A double-peaked Lyman-$α$ emitter in the proximity zone of a quasar at $z\sim 6.6$ Protušová, Klaudia Bosman, Sarah E. I. Wang, Feige Meyer, Romain A. Champagne, Jaclyn B. Davies, Frederick B. Eilers, Anna-Christina Fan, Xiaohui Hennawi, Joseph F. Jin, Xiangyu Jun, Hyunsung D. Kakiichi, Koki Li, Zihao Liu, Weizhe Yang, Jinyi Astrophysics of Galaxies We present a study of a double-peaked Ly$α$ emitter, named LAE-11, found in the proximity zone of QSO J0910-0414 at $z\sim6.6$. We use a combination of deep photometric data from Subaru Telescope, HST, and JWST with spectroscopic data from Keck/DEIMOS, NIRCam WFSS and NIRSpec MSA to characterise the ionising and general properties of the galaxy, as well as the quasar environment surrounding it. We detect Ly$α$, H$β$, [OIII] doublet, and H$α$ emission lines in the various spectral datasets. The presence of a double-peaked Ly$α$ line in the spectrum allows us to characterise the opening angle and lifetime of the QSO as $θ_Q>49.62$° and $t_Q > 3.8\times10^5$ years. LAE-11 is a fairly bright (M$_\rm{UV} = -19.84^{+0.14}_{-0.16}$), blue galaxy with a UV slope of $β= -2.61^{+0.06}_{-0.08}$. Since the galaxy is located in a quasar-ionised region, we have a unique opportunity to measure the escape fraction of Lyman Continuum photons using the un-attenuated double-peaked Ly$α$ emission profile and its equivalent width at such high redshift. We employ diagnostics which do not rely on the detection of Ly$α$ for comparison, and find that all tracers of ionising photon leakage agree within 1$σ$ uncertainty. We measure a moderate escape of Lyman Continuum photons from LAE-11 of $f_\rm{esc}^\rm{LyC} = (8 - 33)\%$. Detections of both H$α$ and H$β$ emission lines allow for separate measurements of the ionising photon production efficiency, resulting with $\log(ξ_\rm{ion}/\rm{Hz~erg^{-1}}) = 25.59\pm0.08$ and $25.65\pm0.09$, for H$α$ and H$β$, respectively. The total ionising output of LAE-11, $\log(f_\rm{esc}^\rm{LyC}ξ_\rm{ion, Hα}/\rm{Hz~erg^{-1}}) = 24.85^{+0.24}_{-0.34}$, is higher than the value of $24.3 - 24.8$ which is traditionally assumed as needed to drive Reionisation forward. |
| title | A unique window into the Epoch of Reionisation: A double-peaked Lyman-$α$ emitter in the proximity zone of a quasar at $z\sim 6.6$ |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2412.12256 |