TY - JOUR
T1 - Chasing the Tail of Cosmic Reionization with Dark Gap Statistics in the Ly
AU - Zhu, Yongda
AU - Becker, George D.
AU - Bosman, Sarah E.I.
AU - Keating, Laura C.
AU - Christenson, Holly M.
AU - Bañados, Eduardo
AU - Bian, Fuyan
AU - Davies, Frederick B.
AU - D’Odorico, Valentina
AU - Eilers, Anna Christina
AU - Fan, Xiaohui
AU - Haehnelt, Martin G.
AU - Kulkarni, Girish
AU - Pallottini, Andrea
AU - Qin, Yuxiang
AU - Wang, Feige
AU - Yang, Jinyi
N1 - Publisher Copyright:
© 2021. The American Astronomical Society. All rights reserved.
PY - 2021/12/20
Y1 - 2021/12/20
N2 - We present a new investigation of the intergalactic medium (IGM) near the end of reionization using “dark gaps” in the Lyα forest. Using spectra of 55 QSOs at z em > 5.5, including new data from the XQR-30 VLT Large Programme, we identify gaps in the Lyα forest where the transmission averaged over 1 comoving h −1 Mpc bins falls below 5%. Nine ultralong (L > 80 h −1 Mpc) dark gaps are identified at z < 6. In addition, we quantify the fraction of QSO spectra exhibiting gaps longer than 30 h −1 Mpc, F 30, as a function of redshift. We measure F 30 ≃ 0.9, 0.6, and 0.15 at z = 6.0, 5.8, and 5.6, respectively, with the last of these long dark gaps persisting down to z ≃5.3. Comparing our results with predictions from hydrodynamical simulations, we find that the data are consistent with models wherein reionization extends significantly below redshift six. Models wherein the IGM is essentially fully reionized that retain large-scale fluctuations in the ionizing UV background at z ≲6 are also potentially consistent with the data. Overall, our results suggest that signatures of reionization in the form of islands of neutral hydrogen and/or large-scale fluctuations in the ionizing background remain present in the IGM until at least z ≃ 5.3.
AB - We present a new investigation of the intergalactic medium (IGM) near the end of reionization using “dark gaps” in the Lyα forest. Using spectra of 55 QSOs at z em > 5.5, including new data from the XQR-30 VLT Large Programme, we identify gaps in the Lyα forest where the transmission averaged over 1 comoving h −1 Mpc bins falls below 5%. Nine ultralong (L > 80 h −1 Mpc) dark gaps are identified at z < 6. In addition, we quantify the fraction of QSO spectra exhibiting gaps longer than 30 h −1 Mpc, F 30, as a function of redshift. We measure F 30 ≃ 0.9, 0.6, and 0.15 at z = 6.0, 5.8, and 5.6, respectively, with the last of these long dark gaps persisting down to z ≃5.3. Comparing our results with predictions from hydrodynamical simulations, we find that the data are consistent with models wherein reionization extends significantly below redshift six. Models wherein the IGM is essentially fully reionized that retain large-scale fluctuations in the ionizing UV background at z ≲6 are also potentially consistent with the data. Overall, our results suggest that signatures of reionization in the form of islands of neutral hydrogen and/or large-scale fluctuations in the ionizing background remain present in the IGM until at least z ≃ 5.3.
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U2 - 10.3847/1538-4357/ac26c2
DO - 10.3847/1538-4357/ac26c2
M3 - Article
AN - SCOPUS:85123545929
VL - 923
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 2
M1 - 223
ER -