Studying dark gaps in Lyman-α forest transmission with large reionization simulations
The physical conditions of the intergalactic medium (IGM) during the final stages of cosmic reionization (<i>z<i/> ∼ 5.0 − 6.0) are not yet fully understood. Recent reports of unexpectedly large-scale (≥150 <i>h<i/><sup>−1<sup/> cMpc) correlation in Lyman (Ly)-<...
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| Autori principali: | , , , |
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| Natura: | Article (Journal) |
| Lingua: | inglese |
| Pubblicazione: |
June 2026
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| In: |
Astronomy and astrophysics
Year: 2026, Volume: 710, Pages: 1-11 |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/202659243 |
| Accesso online: | Verlag, kostenfrei, Volltext: https://doi.org/10.1051/0004-6361/202659243 Verlag, kostenfrei, Volltext: https://www.aanda.org/articles/aa/abs/2026/06/aa59243-26/aa59243-26.html 
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| Note sull'autore: | Barun Maity, Frederick B. Davies, Benedetta Spina, and Sarah E.I. Bosman |
| Riassunto: | The physical conditions of the intergalactic medium (IGM) during the final stages of cosmic reionization (<i>z<i/> ∼ 5.0 − 6.0) are not yet fully understood. Recent reports of unexpectedly large-scale (≥150 <i>h<i/><sup>−1<sup/> cMpc) correlation in Lyman (Ly)-<i>α<i/> transmission flux using extended XQR-30 quasar spectra pose interesting challenges on the reionization end stages. In this work, we investigated the Ly-<i>α<i/> forest dark-gap distribution (defined as regions with transmitted flux below 0.05) as another sensitive tracer of the IGM, using an efficient, large-volume (∼1 Gpc) simulation framework. By constructing a suite of physically motivated model variants (i.e, varying the reionization redshift, IGM temperature, and ionizing-photon mean free path), we generated synthetic sightlines and compared their predicted cumulative distribution of dark gaps with that of observed spectra (at redshift intervals of Δ<i>z<i/> = 0.2). We find that most of the models achieve qualitatively consistent agreement with the data. The scenario with a slightly later reionization completion (<i>z<i/> ∼ 5.4) provides the closest match, whereas a short, constant mean free path model is disfavored by the data at lower redshifts. These findings give qualitative support for the emerging scenario of reionization end extending to <i>z<i/> ≤ 5.7, although they can not rule out a slightly early reionization with enhanced post-ionization ultraviolet (UV) background fluctuations. A similar conclusion arises from the redshift distribution of long dark gap (<i>L<i/> ≥ 30 <i>h<i/><sup>−1<sup/> cMpc) fraction. However, the model variants are still not able to reproduce the observed strong flux correlations at unusually large scales, which remain open for further investigations. |
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| Descrizione del documento: | Online veröffentlicht: 17. Juni 2026 Illustrationen Gesehen am 04.09.2026 |
| Descrizione fisica: | Online Resource |
| ISSN: | 1432-0746 |
| DOI: | 10.1051/0004-6361/202659243 |