Long Dark Gaps in the Lyβ Forest at z < 6: Evidence of Ultra-late Reionization from XQR-30 Spectra
We present a new investigation of the intergalactic medium near reionization using dark gaps in the Ly β forest. With its lower optical depth, Ly β offers a potentially more sensitive probe to any remaining neutral gas compared to the commonly used Ly α line. We identify dark gaps in the Ly β forest...
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2022-01-01
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| author | Yongda Zhu George D. Becker Sarah E. I. Bosman Laura C. Keating Valentina D’Odorico Rebecca L. Davies Holly M. Christenson Eduardo Bañados Fuyan Bian Manuela Bischetti Huanqing Chen Frederick B. Davies Anna-Christina Eilers Xiaohui Fan Prakash Gaikwad Bradley Greig Martin G. Haehnelt Girish Kulkarni Samuel Lai Andrea Pallottini Yuxiang Qin Emma V. Ryan-Weber Fabian Walter Feige Wang Jinyi Yang |
| author_facet | Yongda Zhu George D. Becker Sarah E. I. Bosman Laura C. Keating Valentina D’Odorico Rebecca L. Davies Holly M. Christenson Eduardo Bañados Fuyan Bian Manuela Bischetti Huanqing Chen Frederick B. Davies Anna-Christina Eilers Xiaohui Fan Prakash Gaikwad Bradley Greig Martin G. Haehnelt Girish Kulkarni Samuel Lai Andrea Pallottini Yuxiang Qin Emma V. Ryan-Weber Fabian Walter Feige Wang Jinyi Yang |
| author_sort | Yongda Zhu |
| collection | DOAJ |
| description | We present a new investigation of the intergalactic medium near reionization using dark gaps in the Ly β forest. With its lower optical depth, Ly β offers a potentially more sensitive probe to any remaining neutral gas compared to the commonly used Ly α line. We identify dark gaps in the Ly β forest using spectra of 42 QSOs at z _em > 5.5, including new data from the XQR-30 VLT Large Programme. Approximately 40% of these QSO spectra exhibit dark gaps longer than 10 h ^−1 Mpc at z ≃ 5.8. By comparing the results to predictions from simulations, we find that the data are broadly consistent both with models where fluctuations in the Ly α forest are caused solely by ionizing ultraviolet background fluctuations and with models that include large neutral hydrogen patches at z < 6 due to a late end to reionization. Of particular interest is a very long ( L = 28 h ^−1 Mpc) and dark ( τ _eff ≳ 6) gap persisting down to z ≃ 5.5 in the Ly β forest of the z = 5.85 QSO PSO J025−11. This gap may support late reionization models with a volume-weighted average neutral hydrogen fraction of 〈 x _H I 〉 ≳ 5% by z = 5.6. Finally, we infer constraints on 〈 x _H I 〉 over 5.5 ≲ z ≲ 6.0 based on the observed Ly β dark gap length distribution and a conservative relationship between gap length and neutral fraction derived from simulations. We find 〈 x _H I 〉 ≤ 0.05, 0.17, and 0.29 at z ≃ 5.55, 5.75, and 5.95, respectively. These constraints are consistent with models where reionization ends significantly later than z = 6. |
| format | Article |
| id | doaj-art-aea5311f0ca541eb9802f410d09a174c |
| institution | DOAJ |
| issn | 1538-4357 |
| language | English |
| publishDate | 2022-01-01 |
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| spelling | doaj-art-aea5311f0ca541eb9802f410d09a174c2025-08-20T03:15:03ZengIOP PublishingThe Astrophysical Journal1538-43572022-01-0193227610.3847/1538-4357/ac6e60Long Dark Gaps in the Lyβ Forest at z < 6: Evidence of Ultra-late Reionization from XQR-30 SpectraYongda Zhu0https://orcid.org/0000-0003-3307-7525George D. Becker1https://orcid.org/0000-0003-2344-263XSarah E. I. Bosman2https://orcid.org/0000-0001-8582-7012Laura C. Keating3https://orcid.org/0000-0001-5211-1958Valentina D’Odorico4https://orcid.org/0000-0003-3693-3091Rebecca L. Davies5https://orcid.org/0000-0002-3324-4824Holly M. Christenson6https://orcid.org/0000-0002-0421-065XEduardo Bañados7https://orcid.org/0000-0002-2931-7824Fuyan Bian8https://orcid.org/0000-0002-1620-0897Manuela Bischetti9https://orcid.org/0000-0002-4314-021XHuanqing Chen10https://orcid.org/0000-0002-3211-9642Frederick B. Davies11https://orcid.org/0000-0003-0821-3644Anna-Christina Eilers12https://orcid.org/0000-0003-2895-6218Xiaohui Fan13https://orcid.org/0000-0003-3310-0131Prakash Gaikwad14https://orcid.org/0000-0002-2423-7905Bradley Greig15https://orcid.org/0000-0002-4085-2094Martin G. Haehnelt16https://orcid.org/0000-0001-8443-2393Girish Kulkarni17https://orcid.org/0000-0001-5829-4716Samuel Lai18https://orcid.org/0000-0001-9372-4611Andrea Pallottini19https://orcid.org/0000-0002-7129-5761Yuxiang Qin20https://orcid.org/0000-0002-4314-1810Emma V. Ryan-Weber21https://orcid.org/0000-0002-5360-8103Fabian Walter22https://orcid.org/0000-0003-4793-7880Feige Wang23https://orcid.org/0000-0002-7633-431XJinyi Yang24https://orcid.org/0000-0001-5287-4242Department of Physics & Astronomy, University of California , Riverside, CA 92521, USA ; yzhu144@ucr.eduDepartment of Physics & Astronomy, University of California , Riverside, CA 92521, USA ; yzhu144@ucr.eduMax-Planck-Institut für Astronomie , Königstuhl 17, D-69117 Heidelberg, GermanyLeibniz-Institut für Astrophysik Potsdam (AIP) , An der Sternwarte 16, D-14482 Potsdam, GermanyINAF-Osservatorio Astronomico di Trieste , Via Tiepolo 11, I-34143 Trieste, Italy; Scuola Normale Superiore , Piazza dei Cavalieri 7, I-56126 Pisa, Italy; IFPU-Institute for Fundamental Physics of the Universe , via Beirut 2, I-34151 Trieste, ItalyCentre for Astrophysics and Supercomputing, Swinburne University of Technology , Hawthorn, Victoria 3122, Australia; ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) , AustraliaDepartment of Physics & Astronomy, University of California , Riverside, CA 92521, USA ; yzhu144@ucr.eduMax-Planck-Institut für Astronomie , Königstuhl 17, D-69117 Heidelberg, GermanyEuropean Southern Observatory , Alonso de Córdova 3107, Casilla 19001, Vitacura, Santiago 19, ChileINAF-Osservatorio Astronomico di Trieste , Via Tiepolo 11, I-34143 Trieste, ItalyDepartment of Astronomy & Astrophysics, University of Chicago , Chicago, IL 60637, USAMax-Planck-Institut für Astronomie , Königstuhl 17, D-69117 Heidelberg, GermanyMIT Kavli Institute for Astrophysics and Space Research , 77 Massachusetts Avenue, Cambridge, MA 02139, USASteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USAMax-Planck-Institut für Astronomie , Königstuhl 17, D-69117 Heidelberg, GermanyARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) , Australia; School of Physics, University of Melbourne , Parkville, VIC 3010, AustraliaKavli Institute for Cosmology and Institute of Astronomy , Madingley Road, Cambridge, CB3 0HA, UKTata Institute of Fundamental Research , Homi Bhabha Road, Mumbai 400005, IndiaResearch School of Astronomy and Astrophysics, Australian National University , Canberra, ACT 2611, AustraliaScuola Normale Superiore , Piazza dei Cavalieri 7, I-56126 Pisa, ItalyARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) , Australia; School of Physics, University of Melbourne , Parkville, VIC 3010, AustraliaCentre for Astrophysics and Supercomputing, Swinburne University of Technology , Hawthorn, Victoria 3122, Australia; ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D) , AustraliaMax-Planck-Institut für Astronomie , Königstuhl 17, D-69117 Heidelberg, GermanySteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USASteward Observatory, University of Arizona , 933 North Cherry Avenue, Tucson, AZ 85721, USAWe present a new investigation of the intergalactic medium near reionization using dark gaps in the Ly β forest. With its lower optical depth, Ly β offers a potentially more sensitive probe to any remaining neutral gas compared to the commonly used Ly α line. We identify dark gaps in the Ly β forest using spectra of 42 QSOs at z _em > 5.5, including new data from the XQR-30 VLT Large Programme. Approximately 40% of these QSO spectra exhibit dark gaps longer than 10 h ^−1 Mpc at z ≃ 5.8. By comparing the results to predictions from simulations, we find that the data are broadly consistent both with models where fluctuations in the Ly α forest are caused solely by ionizing ultraviolet background fluctuations and with models that include large neutral hydrogen patches at z < 6 due to a late end to reionization. Of particular interest is a very long ( L = 28 h ^−1 Mpc) and dark ( τ _eff ≳ 6) gap persisting down to z ≃ 5.5 in the Ly β forest of the z = 5.85 QSO PSO J025−11. This gap may support late reionization models with a volume-weighted average neutral hydrogen fraction of 〈 x _H I 〉 ≳ 5% by z = 5.6. Finally, we infer constraints on 〈 x _H I 〉 over 5.5 ≲ z ≲ 6.0 based on the observed Ly β dark gap length distribution and a conservative relationship between gap length and neutral fraction derived from simulations. We find 〈 x _H I 〉 ≤ 0.05, 0.17, and 0.29 at z ≃ 5.55, 5.75, and 5.95, respectively. These constraints are consistent with models where reionization ends significantly later than z = 6.https://doi.org/10.3847/1538-4357/ac6e60ReionizationIntergalactic mediumQuasar absorption line spectroscopyHigh-redshift galaxies |
| spellingShingle | Yongda Zhu George D. Becker Sarah E. I. Bosman Laura C. Keating Valentina D’Odorico Rebecca L. Davies Holly M. Christenson Eduardo Bañados Fuyan Bian Manuela Bischetti Huanqing Chen Frederick B. Davies Anna-Christina Eilers Xiaohui Fan Prakash Gaikwad Bradley Greig Martin G. Haehnelt Girish Kulkarni Samuel Lai Andrea Pallottini Yuxiang Qin Emma V. Ryan-Weber Fabian Walter Feige Wang Jinyi Yang Long Dark Gaps in the Lyβ Forest at z < 6: Evidence of Ultra-late Reionization from XQR-30 Spectra The Astrophysical Journal Reionization Intergalactic medium Quasar absorption line spectroscopy High-redshift galaxies |
| title | Long Dark Gaps in the Lyβ Forest at z < 6: Evidence of Ultra-late Reionization from XQR-30 Spectra |
| title_full | Long Dark Gaps in the Lyβ Forest at z < 6: Evidence of Ultra-late Reionization from XQR-30 Spectra |
| title_fullStr | Long Dark Gaps in the Lyβ Forest at z < 6: Evidence of Ultra-late Reionization from XQR-30 Spectra |
| title_full_unstemmed | Long Dark Gaps in the Lyβ Forest at z < 6: Evidence of Ultra-late Reionization from XQR-30 Spectra |
| title_short | Long Dark Gaps in the Lyβ Forest at z < 6: Evidence of Ultra-late Reionization from XQR-30 Spectra |
| title_sort | long dark gaps in the lyβ forest at z 6 evidence of ultra late reionization from xqr 30 spectra |
| topic | Reionization Intergalactic medium Quasar absorption line spectroscopy High-redshift galaxies |
| url | https://doi.org/10.3847/1538-4357/ac6e60 |
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