A unique window into the Epoch of Reionisation: A double-peaked Lyman-$alpha$ emitter in the proximity zone of a quasar at $zsim 6.6$
Klaudia Protuv{s}ov’a, Sarah E. I. Bosman, Feige Wang, Romain A. Meyer, Jaclyn B. Champagne, Frederick B. Davies, Anna-Christina Eilers, Xiaohui Fan, Joseph F. Hennawi, Xiangyu Jin, Hyunsung D. Jun, Koki Kakiichi, Zihao Li, Jinyi Yang
arXiv:2412.12256v1 Announce Type: new
Abstract: We present a study of a double-peaked Ly$alpha$ emitter, named LAE-11, found in the proximity zone of QSO J0910-0414 at $zsim6.6$. 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$alpha$, H$beta$, [OIII] doublet, and H$alpha$ emission lines in the various spectral datasets. The presence of a double-peaked Ly$alpha$ line in the spectrum allows us to characterise the opening angle and lifetime of the QSO as $theta_Q>49.62${deg} and $t_Q > 3.8times10^5$ years. LAE-11 is a fairly bright (M$_rm{UV} = -19.84^{+0.14}_{-0.16}$), blue galaxy with a UV slope of $beta = -2.61^{+0.06}_{-0.08}$. 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$alpha$ emission profile and its equivalent width at such high redshift. We employ diagnostics which do not rely on the detection of Ly$alpha$ for comparison, and find that all tracers of ionising photon leakage agree within 1$sigma$ 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$alpha$ and H$beta$ emission lines allow for separate measurements of the ionising photon production efficiency, resulting with $log(xi_rm{ion}/rm{Hz~erg^{-1}}) = 25.59pm0.08$ and $25.65pm0.09$, for H$alpha$ and H$beta$, respectively. The total ionising output of LAE-11, $log(f_rm{esc}^rm{LyC}xi_rm{ion, Halpha}/rm{Hz~erg^{-1}}) = 24.85^{+0.24}_{-0.34}$, is higher than the value of $24.3 – 24.8$ which is traditionally assumed as needed to drive Reionisation forward.arXiv:2412.12256v1 Announce Type: new
Abstract: We present a study of a double-peaked Ly$alpha$ emitter, named LAE-11, found in the proximity zone of QSO J0910-0414 at $zsim6.6$. 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$alpha$, H$beta$, [OIII] doublet, and H$alpha$ emission lines in the various spectral datasets. The presence of a double-peaked Ly$alpha$ line in the spectrum allows us to characterise the opening angle and lifetime of the QSO as $theta_Q>49.62${deg} and $t_Q > 3.8times10^5$ years. LAE-11 is a fairly bright (M$_rm{UV} = -19.84^{+0.14}_{-0.16}$), blue galaxy with a UV slope of $beta = -2.61^{+0.06}_{-0.08}$. 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$alpha$ emission profile and its equivalent width at such high redshift. We employ diagnostics which do not rely on the detection of Ly$alpha$ for comparison, and find that all tracers of ionising photon leakage agree within 1$sigma$ 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$alpha$ and H$beta$ emission lines allow for separate measurements of the ionising photon production efficiency, resulting with $log(xi_rm{ion}/rm{Hz~erg^{-1}}) = 25.59pm0.08$ and $25.65pm0.09$, for H$alpha$ and H$beta$, respectively. The total ionising output of LAE-11, $log(f_rm{esc}^rm{LyC}xi_rm{ion, Halpha}/rm{Hz~erg^{-1}}) = 24.85^{+0.24}_{-0.34}$, is higher than the value of $24.3 – 24.8$ which is traditionally assumed as needed to drive Reionisation forward.