{"citation":{"mla":"Heintz, Kasper E., et al. “A Dense Web of Neutral Gas in a Galaxy Proto-Cluster Post-Reionization.” <i>Nature Astronomy</i>, Springer Nature, 2026, doi:<a href=\"https://doi.org/10.1038/s41550-025-02745-x\">10.1038/s41550-025-02745-x</a>.","ieee":"K. E. Heintz <i>et al.</i>, “A dense web of neutral gas in a galaxy proto-cluster post-reionization,” <i>Nature Astronomy</i>. Springer Nature, 2026.","ista":"Heintz KE, Bennett JS, Oesch PA, Sneppen A, Rennehan D, Pollock CL, Witstok J, Smit R, Vejlgaard S, Terp C, Koca US, Brammer GB, Finlator K, Hayes MJ, Sijacki D, Naidu RP, Matthee JJ, Valentino F, Tanvir NR, Jakobsson P, Laursen P, Watson DJ, Davé R, Keating LC, Covelo-Paz A. 2026. A dense web of neutral gas in a galaxy proto-cluster post-reionization. Nature Astronomy.","chicago":"Heintz, Kasper E., Jake S. Bennett, Pascal A. Oesch, Albert Sneppen, Douglas Rennehan, Clara L. Pollock, Joris Witstok, et al. “A Dense Web of Neutral Gas in a Galaxy Proto-Cluster Post-Reionization.” <i>Nature Astronomy</i>. Springer Nature, 2026. <a href=\"https://doi.org/10.1038/s41550-025-02745-x\">https://doi.org/10.1038/s41550-025-02745-x</a>.","apa":"Heintz, K. E., Bennett, J. S., Oesch, P. A., Sneppen, A., Rennehan, D., Pollock, C. L., … Covelo-Paz, A. (2026). A dense web of neutral gas in a galaxy proto-cluster post-reionization. <i>Nature Astronomy</i>. Springer Nature. <a href=\"https://doi.org/10.1038/s41550-025-02745-x\">https://doi.org/10.1038/s41550-025-02745-x</a>","short":"K.E. Heintz, J.S. Bennett, P.A. Oesch, A. Sneppen, D. Rennehan, C.L. Pollock, J. Witstok, R. Smit, S. Vejlgaard, C. Terp, U.S. Koca, G.B. Brammer, K. Finlator, M.J. Hayes, D. Sijacki, R.P. Naidu, J.J. Matthee, F. Valentino, N.R. Tanvir, P. Jakobsson, P. Laursen, D.J. Watson, R. Davé, L.C. Keating, A. Covelo-Paz, Nature Astronomy (2026).","ama":"Heintz KE, Bennett JS, Oesch PA, et al. A dense web of neutral gas in a galaxy proto-cluster post-reionization. <i>Nature Astronomy</i>. 2026. doi:<a href=\"https://doi.org/10.1038/s41550-025-02745-x\">10.1038/s41550-025-02745-x</a>"},"article_type":"original","scopus_import":"1","department":[{"_id":"JoMa"}],"oa_version":"None","publication_status":"epub_ahead","type":"journal_article","date_published":"2026-01-02T00:00:00Z","OA_type":"closed access","publisher":"Springer Nature","doi":"10.1038/s41550-025-02745-x","date_created":"2026-01-11T23:01:34Z","status":"public","article_processing_charge":"No","date_updated":"2026-01-12T09:53:21Z","quality_controlled":"1","publication_identifier":{"eissn":["2397-3366"]},"abstract":[{"text":"Galaxy clusters are the most massive, gravitationally bound structures in the Universe. They emerged through hierarchical structure formation of large-scale dark matter and baryon overdensities. Early galaxy ‘proto-clusters’ are believed to have substantially contributed to the cosmic star-formation rate density and served as ‘hotspots’ for the reionization of the intergalactic medium. Our understanding of the formation of these structures at the earliest cosmic epochs is, however, limited to sparse observations of their galaxy members or is based on phenomenological models and cosmological simulations. Here we report the detection of a large and coherent structure of neutral atomic hydrogen gas (H i) extending from a galaxy proto-cluster at redshift z = 5.4, one billion years after the Big Bang. The presence of this H i gas is revealed by strong damped Lyman-α absorption features observed in several background-galaxy spectra. Although the sight lines overall probe a large range in H i column densities, NHI = 1020 cm−2 to 1023.5 cm−2, they are similar across nearby sight lines, demonstrating that they probe the same dense neutral gas. This observation of a dense large-scale overdensity of cold neutral gas challenges current cosmological simulations and has strong implications for the reionization topology of the Universe.","lang":"eng"}],"publication":"Nature Astronomy","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","day":"02","year":"2026","_id":"20975","title":"A dense web of neutral gas in a galaxy proto-cluster post-reionization","language":[{"iso":"eng"}],"author":[{"full_name":"Heintz, Kasper E.","first_name":"Kasper E.","last_name":"Heintz"},{"full_name":"Bennett, Jake S.","first_name":"Jake S.","last_name":"Bennett"},{"first_name":"Pascal A.","full_name":"Oesch, Pascal A.","last_name":"Oesch"},{"full_name":"Sneppen, Albert","first_name":"Albert","last_name":"Sneppen"},{"last_name":"Rennehan","first_name":"Douglas","full_name":"Rennehan, Douglas"},{"last_name":"Pollock","full_name":"Pollock, Clara L.","first_name":"Clara L."},{"full_name":"Witstok, Joris","first_name":"Joris","last_name":"Witstok"},{"last_name":"Smit","full_name":"Smit, Renske","first_name":"Renske"},{"first_name":"Simone","full_name":"Vejlgaard, Simone","last_name":"Vejlgaard"},{"last_name":"Terp","full_name":"Terp, Chamilla","first_name":"Chamilla"},{"last_name":"Koca","full_name":"Koca, Umran S.","first_name":"Umran S."},{"last_name":"Brammer","full_name":"Brammer, Gabriel B.","first_name":"Gabriel B."},{"first_name":"Kristian","full_name":"Finlator, Kristian","last_name":"Finlator"},{"full_name":"Hayes, Matthew J.","first_name":"Matthew J.","last_name":"Hayes"},{"full_name":"Sijacki, Debora","first_name":"Debora","last_name":"Sijacki"},{"last_name":"Naidu","full_name":"Naidu, Rohan P.","first_name":"Rohan P."},{"last_name":"Matthee","full_name":"Matthee, Jorryt J","first_name":"Jorryt J","orcid":"0000-0003-2871-127X","id":"7439a258-f3c0-11ec-9501-9df22fe06720"},{"first_name":"Francesco","full_name":"Valentino, Francesco","last_name":"Valentino"},{"full_name":"Tanvir, Nial R.","first_name":"Nial R.","last_name":"Tanvir"},{"first_name":"Páll","full_name":"Jakobsson, Páll","last_name":"Jakobsson"},{"last_name":"Laursen","full_name":"Laursen, Peter","first_name":"Peter"},{"first_name":"Darach J.","full_name":"Watson, Darach J.","last_name":"Watson"},{"first_name":"Romeel","full_name":"Davé, Romeel","last_name":"Davé"},{"full_name":"Keating, Laura C.","first_name":"Laura C.","last_name":"Keating"},{"last_name":"Covelo-Paz","first_name":"Alba","full_name":"Covelo-Paz, Alba"}],"acknowledgement":"This work has received funding from the Swiss State Secretariat for Education, Research and Innovation (Contract No. MB22.00072). The Cosmic Dawn Center (DAWN) is funded by the Danish National Research Foundation (Grant No. DNRF140). The data products presented herein were retrieved from the DJA, which is an initiative of the Cosmic Dawn Center. This work is based on observations made with the NASA/ESA/CSA JWST. The data were obtained from MAST at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. J.S.B. acknowledges support from the Simons Collaboration on Learning the Universe. J.S.B.’s simulations used resources from the Cambridge Service for Data Driven Discovery operated by the University of Cambridge Research Computing Service (www.csd3.cam.ac.uk), provided by Dell EMC and Intel using tier 2 funding from the Engineering and Physical Sciences Research Council (Capital Grant No. EP/P020259/1). K.F. gratefully acknowledges support from the National Science Foundation (Award No. 2006550). M.J.H. is fellow of the Knut & Alice Wallenberg Foundation. D.S. acknowledges support from the Science and Technology Facilities Council. U.S.K. was partially funded by the Summer Undergraduate Research Fellowships programme at Caltech.","month":"01"}