TY - JOUR
T1 - Chronicling the Reionization History at 6 ≲ z ≲ 7 with Emergent Quasar Damping Wings
AU - Ďurovčíková, Dominika
AU - Eilers, Anna-Christina
AU - Chen, Huanqing
AU - Satyavolu, Sindhu
AU - Kulkarni, Girish
AU - Simcoe, Robert A.
AU - Keating, Laura C.
AU - Haehnelt, Martin G.
AU - Bañados, Eduardo
N1 - 28 pages, 14 figures
PY - 2024/7/10
Y1 - 2024/7/10
N2 - The spectra of high-redshift (z ≳ 6) quasars contain valuable information on the progression of the Epoch of Reionization. At redshifts z < 6, the observed Lyman-series forest shows that the intergalactic medium is nearly ionized, while at z > 7 the observed quasar damping wings indicate high neutral gas fractions. However, there remains a gap in neutral gas fraction constraints at 6 ≲ z ≲ 7 where the Lyman-series forest becomes saturated but damping wings have yet to fully emerge. In this work, we use a sample of 18 quasar spectra at redshifts 6.0 < z < 7.1 to close this gap. We apply neural networks to reconstruct the quasars’ continuum emission around the partially absorbed Lyα line to normalize their spectra, and stack these continuum-normalized spectra in three redshift bins. To increase the robustness of our results, we compare the stacks to a grid of models from two hydrodynamical simulations, ATON and CROC, and we measure the volume-averaged neutral gas fraction, x ¯ HI , while jointly fitting for the mean quasar lifetime, t
Q, for each stacked spectrum. We chronicle the evolution of neutral gas fraction using the ATON (CROC) models as follows: x ¯ HI = 0.21 − 0.07 + 0.17 ( x ¯ HI = 0.10 < 10 − 4 + 0.73 ) at 〈z〉 = 6.10, x ¯ HI = 0.21 − 0.07 + 0.33 ( x ¯ HI = 0.57 − 0.47 + 0.26 ) at 〈z〉 = 6.46, and x ¯ HI = 0.37 − 0.17 + 0.17 ( x ¯ HI = 0.57 − 0.21 + 0.26 ) at 〈z〉 = 6.87. At the same time, we constrain the average quasar lifetime to be t
Q ≲ 7 Myr across all redshift bins, in good agreement with previous studies.
AB - The spectra of high-redshift (z ≳ 6) quasars contain valuable information on the progression of the Epoch of Reionization. At redshifts z < 6, the observed Lyman-series forest shows that the intergalactic medium is nearly ionized, while at z > 7 the observed quasar damping wings indicate high neutral gas fractions. However, there remains a gap in neutral gas fraction constraints at 6 ≲ z ≲ 7 where the Lyman-series forest becomes saturated but damping wings have yet to fully emerge. In this work, we use a sample of 18 quasar spectra at redshifts 6.0 < z < 7.1 to close this gap. We apply neural networks to reconstruct the quasars’ continuum emission around the partially absorbed Lyα line to normalize their spectra, and stack these continuum-normalized spectra in three redshift bins. To increase the robustness of our results, we compare the stacks to a grid of models from two hydrodynamical simulations, ATON and CROC, and we measure the volume-averaged neutral gas fraction, x ¯ HI , while jointly fitting for the mean quasar lifetime, t
Q, for each stacked spectrum. We chronicle the evolution of neutral gas fraction using the ATON (CROC) models as follows: x ¯ HI = 0.21 − 0.07 + 0.17 ( x ¯ HI = 0.10 < 10 − 4 + 0.73 ) at 〈z〉 = 6.10, x ¯ HI = 0.21 − 0.07 + 0.33 ( x ¯ HI = 0.57 − 0.47 + 0.26 ) at 〈z〉 = 6.46, and x ¯ HI = 0.37 − 0.17 + 0.17 ( x ¯ HI = 0.57 − 0.21 + 0.26 ) at 〈z〉 = 6.87. At the same time, we constrain the average quasar lifetime to be t
Q ≲ 7 Myr across all redshift bins, in good agreement with previous studies.
KW - astro-ph.CO
KW - astro-ph.GA
U2 - 10.3847/1538-4357/ad4888
DO - 10.3847/1538-4357/ad4888
M3 - Article
SN - 0004-637X
VL - 969
SP - 1
EP - 22
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 2
M1 - 162
ER -