Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Article
  • Published:

Sunyaev–Zeldovich detection of hot intracluster gas at redshift 4.3

Nature volume 649, pages 1130–1133 (2026)Cite this article

Subjects

Abstract

Most baryons in present-day galaxy clusters exist as hot gas (≳107 K), forming the intracluster medium (ICM)1. Cosmological simulations predict that the mass and temperature of the ICM decline towards earlier times, as intracluster gas in younger clusters is still assembling and being heated2,3,4. To date, hot ICM has been securely detected only in a few systems at or above z ≈ 2, leaving the timing and mechanism of ICM assembly uncertain5,6,7. Here we report the direct observation of hot intracluster gas via its thermal Sunyaev–Zeldovich signature in the protocluster SPT2349–56 with the Atacama Large Millimeter/submillimeter Array. SPT2349–56 hosts a large molecular gas reservoir and three radio-loud active galactic nuclei (AGN) within an approximately 100-kpc region at z = 4.3 (refs. 8,9,10,11). The measurement implies a thermal energy of  about 1061 erg in the core, about 10 times more than gravity alone should produce. Contrary to current theoretical expectations3,4,12, the hot ICM in SPT2349–56 demonstrates that substantial heating can occur very early in cluster assembly, depositing enough energy to overheat the nascent ICM well before mature clusters become common at z ≈ 2.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on SpringerLink
  • Instant access to the full article PDF.

USD 39.95

Prices may be subject to local taxes which are calculated during checkout

Fig. 1: RGB image of the protocluster SPT2349–56 with tSZ decrement contours.
Fig. 2: Redshift evolution of the mass-normalized Compton-Y parameter.

Similar content being viewed by others

Data availability

The ALMA (2015.1.01543.T, 2017.1.00273.S, 2022.1.00495.S and 2023.1.00124.S), JWST (JWST-GO-06669), and HST (HST-GO-15701) data used in this work are publicly available on the ALMA science archive (https://almascience.nrao.edu/aq/) and MAST service (https://mast.stsci.edu).

Code availability

No custom code central to the conclusions was used. The results presented can be reproduced using the following publicly available packages: astropy81, astroquery82, CASA83, colossus65, matplotlib84, numpy85, pandas86, photutils58, spectral_cube87, uvplot61.

References

  1. Bryan, G. L. & Norman, M. L. Statistical properties of X-ray clusters: analytic and numerical comparisons. Astrophys. J. 495, 80–99 (1998).

    Article  ADS  Google Scholar 

  2. Chiang, Y.-K., Makiya, R., Ménard, B. & Komatsu, E. The cosmic thermal history probed by Sunyaev–Zeldovich effect tomography. Astrophys. J. 902, 56 (2020).

    Article  ADS  CAS  Google Scholar 

  3. Li, Q. et al. THE THREE HUNDRED Project: the evolution of physical baryon profiles. Mon. Not. R. Astron. Soc. 523, 1228–1246 (2023).

    Article  ADS  CAS  Google Scholar 

  4. Rohr, E. et al. The cooler past of the intracluster medium in TNG-cluster. Mon. Not. R. Astron. Soc. 536, 1226–1250 (2025).

    Article  ADS  CAS  Google Scholar 

  5. Mantz, A. B. et al. The XXL Survey. XVII. X-ray and Sunyaev–Zel’dovich properties of the redshift 2.0 galaxy cluster XLSSC 122. Astron. Astrophys. 620, 2 (2018).

    Article  Google Scholar 

  6. Gobat, R. et al. Sunyaev-Zel’dovich detection of the galaxy cluster Cl J1449+0856 at z = 1.99: the pressure profile in uv space. Astron. Astrophys. 629, 104 (2019).

    Article  Google Scholar 

  7. Di Mascolo, L. et al. Forming intracluster gas in a galaxy protocluster at a redshift of 2.16. Nature 615, 809–812 (2023).

    Article  ADS  PubMed  PubMed Central  Google Scholar 

  8. Miller, T. B. et al. A massive core for a cluster of galaxies at a redshift of 4.3. Nature 556, 469–472 (2018).

    Article  ADS  CAS  PubMed  Google Scholar 

  9. Chapman, S. C. et al. Brightest cluster galaxy formation in the z = 4.3 protocluster SPT 2349-56: discovery of a radio-loud active galactic nucleus. Astrophys. J. 961, 120 (2024).

    Article  ADS  Google Scholar 

  10. Zhou, D. et al. A large molecular gas reservoir in the protocluster SPT2349-56 at z = 4.3. Astrophys. J. Lett. 982, 17 (2025).

    Article  ADS  Google Scholar 

  11. Chapman, S. C. et al. An overabundance of radio-AGN in the SPT2349-56 protocluster: preheating the intra-cluster medium. Preprint at https://arxiv.org/abs/2511.17814 (2025).

  12. Sunyaev, R. A. & Zeldovich, Y. B. Formation of clusters of galaxies; protocluster fragmentation and intergalactic gas heating. Astron. Astrophys. 20, 189 (1972).

    ADS  Google Scholar 

  13. Sunyaev, R. A. & Zeldovich, I. B. Microwave background radiation as a probe of the contemporary structure and history of the universe. Annu. Rev. Astron. Astrophys. 18, 537–560 (1980).

    Article  ADS  CAS  Google Scholar 

  14. Voit, G. M. Tracing cosmic evolution with clusters of galaxies. Rev. Mod. Phys. 77, 207–258 (2005).

    Article  ADS  CAS  Google Scholar 

  15. Wang, G. C. P. et al. Overdensities of submillimetre-bright sources around candidate protocluster cores selected from the South Pole Telescope survey. Mon. Not. R. Astron. Soc. 508, 3754–3770 (2021).

    Article  ADS  CAS  Google Scholar 

  16. Hill, R. et al. Megaparsec-scale structure around the protocluster core SPT2349-56 at z = 4.3. Mon. Not. R. Astron. Soc. 495, 3124–3159 (2020).

    Article  ADS  CAS  Google Scholar 

  17. McCarthy, I. G., Babul, A., Bower, R. G. & Balogh, M. L. Towards a holistic view of the heating and cooling of the intracluster medium. Mon. Not. R. Astron. Soc. 386, 1309–1331 (2008).

    Article  ADS  CAS  Google Scholar 

  18. Henden, N. A., Puchwein, E. & Sijacki, D. The redshift evolution of X-ray and Sunyaev-Zel’dovich scaling relations in the FABLE simulations. Mon. Not. R. Astron. Soc. 489, 2439–2470 (2019).

    Article  ADS  CAS  Google Scholar 

  19. Bennett, J. S., Sijacki, D., Costa, T., Laporte, N. & Witten, C. The growth of the gargantuan black holes powering high-redshift quasars and their impact on the formation of early galaxies and protoclusters. Mon. Not. R. Astron. Soc. 527, 1033–1054 (2024).

    Article  ADS  CAS  Google Scholar 

  20. Carlstrom, J. E., Holder, G. P. & Reese, E. D. Cosmology with the Sunyaev-Zel’dovich effect. Annu. Rev. Astron. Astrophys. 40, 643–680 (2002).

    Article  ADS  Google Scholar 

  21. Mroczkowski, T. et al. Astrophysics with the spatially and spectrally resolved Sunyaev-Zeldovich effects. A millimetre/submillimetre probe of the warm and hot universe. Space Sci. Rev. 215, 17 (2019).

    Article  ADS  Google Scholar 

  22. Spacek, A., Scannapieco, E., Cohen, S., Joshi, B. & Mauskopf, P. Constraining AGN feedback in massive ellipticals with South Pole telescope measurements of the thermal Sunyaev-Zel’dovich effect. Astrophys. J. 819, 128 (2016).

    Article  ADS  Google Scholar 

  23. Arnaud, M. et al. The universal galaxy cluster pressure profile from a representative sample of nearby systems (REXCESS) and the YSZ–M500 relation. Astron. Astrophys. 517, 92 (2010).

    Article  Google Scholar 

  24. Maughan, B. J., Giles, P. A., Randall, S. W., Jones, C. & Forman, W. R. Self-similar scaling and evolution in the galaxy cluster X-ray luminosity-temperature relation. Mon. Not. R. Astron. Soc. 421, 1583–1602 (2012).

    Article  ADS  Google Scholar 

  25. Planck Collaboration. Planck 2013 results. XX. Cosmology from Sunyaev-Zeldovich cluster counts. Astron. Astrophys. 571, 20 (2014).

    Article  Google Scholar 

  26. McDonald, M. et al. The remarkable similarity of massive galaxy clusters from z ~ 0 to z ~ 1.9. Astrophys. J. 843, 28 (2017).

    Article  ADS  Google Scholar 

  27. Mostoghiu, R. et al. The Three Hundred Project: the evolution of galaxy cluster density profiles. Mon. Not. R. Astron. Soc. 483, 3390–3403 (2019).

    Article  ADS  CAS  Google Scholar 

  28. Marrone, D. P. et al. LoCuSS: the Sunyaev-Zel’dovich effect and weak-lensing mass scaling relation. Astrophys. J. 754, 119 (2012).

    Article  ADS  Google Scholar 

  29. Bocquet, S. et al. Cluster cosmology constraints from the 2500 deg2 SPT-SZ survey: inclusion of weak gravitational lensing data from Magellan and the Hubble Space Telescope. Astrophys. J. 878, 55 (2019).

    Article  ADS  CAS  Google Scholar 

  30. Bigwood, L., Bourne, M. A., Iršič, V., Amon, A. & Sijacki, D. The case for large-scale AGN feedback in galaxy formation simulations: insights from XFABLE. Mon. Not. R. Astron. Soc. 542, 3206–3230 (2025).

  31. Lucie-Smith, L. et al. Cosmological feedback from a halo assembly perspective. Phys. Rev. D. 112, 063541 (2025).

  32. Nagarajan, A. et al. Weak-lensing mass calibration of the Sunyaev-Zel’dovich effect using APEX-SZ galaxy clusters. Mon. Not. R. Astron. Soc. 488, 1728–1759 (2019).

    Article  ADS  CAS  Google Scholar 

  33. Andreon, S. et al. Witnessing the intracluster medium assembly at the cosmic noon in JKCS 041. Mon. Not. R. Astron. Soc. 522, 4301–4309 (2023).

    Article  ADS  CAS  Google Scholar 

  34. van Marrewijk, J. et al. XLSSC 122 caught in the act of growing up: spatially resolved SZ observations of a z = 1.98 galaxy cluster. Astron. Astrophys. 689, 41 (2024).

    Article  Google Scholar 

  35. Remus, R.-S., Dolag, K. & Dannerbauer, H. The young and the wild: what happens to protoclusters forming at redshift z ≈ 4? Astrophys. J. 950, 191 (2023).

    Article  ADS  Google Scholar 

  36. Aljamal, E. et al. Mass proxy quality of massive halo properties in the IllustrisTNG and FLAMINGO simulations: I. Hot gas. Mon. Not. R. Astron. Soc. 544, 67–94 (2025).

  37. Bassini, L. et al. The DIANOGA simulations of galaxy clusters: characterising star formation in protoclusters. Astron. Astrophys. 642, 37 (2020).

    Article  Google Scholar 

  38. Lim, S. et al. Is there enough star formation in simulated protoclusters? Mon. Not. R. Astron. Soc. 501, 1803–1822 (2021).

    Article  ADS  CAS  Google Scholar 

  39. Hlavacek-Larrondo, J. et al. X-ray cavities in a sample of 83 SPT-selected clusters of galaxies: tracing the evolution of AGN feedback in clusters of galaxies out to z = 1.2. Astrophys. J. 805, 35 (2015).

    Article  ADS  Google Scholar 

  40. Valentino, F. et al. A giant Lyα nebula in the core of an X-ray cluster at z = 1.99: implications for early energy injection. Astrophys. J. 829, 53 (2016).

    Article  ADS  Google Scholar 

  41. Cielo, S., Babul, A., Antonuccio-Delogu, V., Silk, J. & Volonteri, M. Feedback from reorienting AGN jets. I. Jet-ICM coupling, cavity properties and global energetics. Astron. Astrophys. 617, 58 (2018).

    Article  ADS  Google Scholar 

  42. Heckman, T. M. & Best, P. N. A global inventory of feedback. Galaxies 11, 21 (2023).

    Article  ADS  Google Scholar 

  43. Heckman, T. M., Roy, N., Best, P. N. & Kondapally, R. Mergers, radio jets, and quenching star formation in massive galaxies: quantifying their synchronized cosmic evolution and assessing the energetics. Astrophys. J. 977, 125 (2024).

    Article  ADS  Google Scholar 

  44. Rennehan, D., Babul, A., Moa, B. & Davé, R. The OBSIDIAN model: three regimes of black hole feedback. Mon. Not. R. Astron. Soc. 532, 4793–4809 (2024).

    Article  ADS  CAS  Google Scholar 

  45. Huško, F. et al. A hybrid active galactic nucleus feedback model with spinning black holes, winds and jets. Preprint at arxiv.org/abs/2509.05179 (2025)

  46. Begelman, M. C. & Cioffi, D. F. Overpressured cocoons in extragalactic radio sources. Astrophys. J. Lett. 345, 21 (1989).

    Article  ADS  Google Scholar 

  47. Nesvadba, N. P. H., Lehnert, M. D., De Breuck, C., Gilbert, A. M. & van Breugel, W. Evidence for powerful AGN winds at high redshift: dynamics of galactic outflows in radio galaxies during the “Quasar Era”. Astron. Astrophys. 491, 407–424 (2008).

    Article  ADS  CAS  Google Scholar 

  48. Fabian, A. C. Observational evidence of active galactic nuclei feedback. Annu. Rev. Astron. Astrophys. 50, 455–489 (2012).

    Article  ADS  CAS  Google Scholar 

  49. Chadayammuri, U., Tremmel, M., Nagai, D., Babul, A. & Quinn, T. Fountains and storms: the effects of AGN feedback and mergers on the evolution of the intracluster medium in the ROMULUSC simulation. Mon. Not. R. Astron. Soc. 504, 3922–3937 (2021).

    Article  ADS  CAS  Google Scholar 

  50. Grayson, S., Scannapieco, E. & Davé, R. Distinguishing active galactic nuclei feedback models with the thermal Sunyaev–Zel’dovich effect. Astrophys. J. 957, 17 (2023).

    Article  ADS  CAS  Google Scholar 

  51. Altamura, E. et al. EAGLE-like simulation models do not solve the entropy core problem in groups and clusters of galaxies. Mon. Not. R. Astron. Soc. 520, 3164–3186 (2023).

    Article  ADS  CAS  Google Scholar 

  52. Gardner, A., Baxter, E., Raghunathan, S., Cui, W. & Ceverino, D. Prospects for studying the mass and gas in protoclusters with future CMB observations. Open J. Astrophys. 7, 2 (2024).

    Article  ADS  Google Scholar 

  53. Vogelsberger, M. et al. The uniformity and time-invariance of the intra-cluster metal distribution in galaxy clusters from the IllustrisTNG simulations. Mon. Not. R. Astron. Soc. 474, 2073–2093 (2018).

    Article  ADS  CAS  Google Scholar 

  54. Huško, F., Lacey, C. G., Schaye, J., Nobels, F. S. J. & Schaller, M. Winds versus jets: a comparison between black hole feedback modes in simulations of idealized galaxy groups and clusters. Mon. Not. R. Astron. Soc. 527, 5988–6020 (2024).

    Article  ADS  Google Scholar 

  55. Mantz, A. B. et al. The XXL Survey. V. Detection of the Sunyaev-Zel’dovich effect of the redshift 1.9 galaxy cluster XLSSU J021744.1-034536 with CARMA. Astrophys. J. 794, 157 (2014).

    Article  ADS  Google Scholar 

  56. Planck Collaboration. Planck 2015 results. XIII. Cosmological parameters. Astron. Astrophys. 594, 13 (2016).

    Article  Google Scholar 

  57. Bushouse, H. et al. JWST calibration pipeline. Zenodo https://doi.org/10.5281/zenodo.6984365 (2025).

  58. Bradley, L. et al. Astropy/photutils: 2.0.2. Zenodo https://doi.org/10.5281/zenodo.13989456 (2024).

  59. Fujimoto, S. et al. ALMA census of faint 1.2 mm sources down to ~0.02 mJy: extragalactic background light and dust-poor, high-z galaxies. Astrophys. J. Suppl. Ser. 222, 1 (2016).

    Article  ADS  Google Scholar 

  60. Fujimoto, S. et al. ALMA Lensing Cluster Survey: deep 1.2 mm number counts and infrared luminosity functions at z = 1–8. Astrophys. J. Suppl. Ser. 275, 36 (2024).

    Article  ADS  Google Scholar 

  61. Tazzari, M. Mtazzari/uvplot (v0.1.1). Zenodo https://doi.org/10.5281/zenodo.1003113 (2017).

  62. Wang, T. et al. Discovery of a galaxy cluster with a violently starbursting core at z = 2.506. Astrophys. J. 828, 56 (2016).

    Article  ADS  Google Scholar 

  63. Grishin, K. A. et al. Spectroscopic confirmation of the galaxy clusters CARLA J0950+2743 at z = 2.363 and CARLA-Ser J0950+2743 at z = 2.243. Astron. Astrophys. 693, 1 (2025).

    Article  Google Scholar 

  64. Travascio, A. et al. X-ray view of a massive node of the cosmic web at z = 3 II. Discovery of extended X-ray emission around a hyperluminous QSO. Preprint at arxiv.org/abs/2508.20074 (2025).

  65. Diemer, B. COLOSSUS: a Python toolkit for cosmology, large-scale structure, and dark matter halos. Astrophys. J. Suppl. Ser. 239, 35 (2018).

    Article  ADS  CAS  Google Scholar 

  66. Diemer, B. & Joyce, M. An accurate physical model for halo concentrations. Astrophys. J. 871, 168 (2019).

    Article  ADS  CAS  Google Scholar 

  67. Hill, R. et al. Rapid build-up of the stellar content in the protocluster core SPT2349-56 at z = 4.3. Mon. Not. R. Astron. Soc. 512, 4352–4377 (2022).

    Article  ADS  Google Scholar 

  68. Vito, F. et al. Fast supermassive black hole growth in the SPT2349–56 protocluster at z = 4.3. Astron. Astrophys. 689, A130 (2024).

    Article  CAS  Google Scholar 

  69. Heckman, T. M. & Best, P. N. The coevolution of galaxies and supermassive black holes: insights from surveys of the contemporary Universe. Annu. Rev. Astron. Astrophys. 52, 589–660 (2014).

    Article  ADS  Google Scholar 

  70. Nusser, A., Silk, J. & Babul, A. Suppressing cluster cooling flows by self-regulated heating from a spatially distributed population of active galactic nuclei. Mon. Not. R. Astron. Soc. 373, 739–746 (2006).

    Article  ADS  CAS  Google Scholar 

  71. Jennings, F. J., Babul, A., Davé, R., Cui, W. & Rennehan, D. HYENAS: X-ray bubbles and cavities in the intragroup medium. Mon. Not. R. Astron. Soc. 536, 145–165 (2025).

    Article  ADS  Google Scholar 

  72. Kondapally, R. et al. Cosmic evolution of radio-AGN feedback: confronting models with data. Mon. Not. R. Astron. Soc. 523, 5292–5305 (2023).

    Article  ADS  Google Scholar 

  73. Venkateshwaran, A. et al. Kinematic analysis of z = 4.3 galaxies in the SPT2349–56 protocluster core. Astrophys. J. 977, 161 (2024).

  74. Spilker, J. S. et al. Ubiquitous molecular outflows in z > 4 massive, dusty galaxies. II. Momentum-driven winds powered by star formation in the early Universe. Astrophys. J. 905, 86 (2020).

    Article  ADS  CAS  Google Scholar 

  75. Duan, X. & Guo, F. On the energy coupling efficiency of AGN outbursts in galaxy clusters. Astrophys. J. 896, 114 (2020).

    Article  ADS  Google Scholar 

  76. O’Dea, C. P. The compact steep-spectrum and gigahertz peaked-spectrum radio sources. Publ. Astron. Soc. Pac. 110, 493–532 (1998).

    Article  ADS  Google Scholar 

  77. Yamada, M., Sugiyama, N. & Silk, J. The Sunyaev-Zeldovich effect by cocoons of radio galaxies. Astrophys. J. 522, 66–73 (1999).

    Article  ADS  Google Scholar 

  78. Bromberg, O., Nakar, E., Piran, T. & Sari, R. The propagation of relativistic jets in external media. Astrophys. J. 740, 100 (2011).

    Article  ADS  Google Scholar 

  79. Cen, R. Global preventive feedback of powerful radio jets on galaxy formation. Proc. Natl Acad. Sci. USA 121, 2402435121 (2024).

    Article  MathSciNet  Google Scholar 

  80. Boselli, A., Fossati, M. & Sun, M. Ram pressure stripping in high-density environments. Astron. Astrophys. Rev. 30, 3 (2022).

    Article  ADS  Google Scholar 

  81. Astropy Collaboration. The Astropy Project: sustaining and growing a community-oriented open-source project and the latest major release (v5.0) of the core package. Astrophys. J. 935, 167 (2022).

    Article  ADS  Google Scholar 

  82. Ginsburg, A. et al. astroquery: an astronomical web-querying package in Python. Astron. J. 157, 98 (2019).

    Article  ADS  Google Scholar 

  83. CASA Team. CASA, the common astronomy software applications for radio astronomy. Publ. Astron. Soc. Pac. 134, 114501 (2022).

    Article  ADS  Google Scholar 

  84. Hunter, J. D. Matplotlib: a 2D graphics environment. Comput. Sci. Eng. 9, 90–95 (2007).

    Article  Google Scholar 

  85. Harris, C. R. et al. Array programming with NumPy. Nature 585, 357–362 (2020).

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  86. The pandas development team. pandas-dev/pandas: Pandas. Zenodo https://doi.org/10.5281/zenodo.3509134 (2025).

  87. Ginsburg, A. et al. radio-astro-tools/spectral-cube: v.0.4.4. Zenodo https://doi.org/10.5281/zenodo.2573901 (2019).

Download references

Acknowledgements

We thank L. Sage for his guidance and feedback, which greatly improved the clarity and presentation of the paper. We thank S. Andreon, A. Babul, L. Bleem, G. Holder, A. Mantz, D. Marrone, D. Nagai, A. Richards, D. Rennehan, J. Sayers, D. Wang, B. Yue and N. Zhang for their discussions on this work. We thank the anonymous referees for their comments and suggestions, which improved the clarity of this work. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2015.1.01543.T, ADS/JAO.ALMA#2017.1.00273.S, ADS/JAO.ALMA#2022.1.00495.S and ADS/JAO.ALMA#2023.1.00124.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), NSTC and ASIAA (Taiwan) and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities. This research used the Canadian Advanced Network for Astronomy Research (CANFAR) operated in partnership by the Canadian Astronomy Data Centre and The Digital Research Alliance of Canada, with support from the National Research Council of Canada, the Canadian Space Agency, CANARIE and the Canadian Foundation for Innovation. This research is based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, under NASA contract no. NAS 5-26555. These observations are associated with program #15701. This work is based (in part) on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, under NASA contract no. NAS 5-03127 for JWST. These observations are associated with program #06669. This research was supported in part by grant NSF PHY-2309135 to the Kavli Institute for Theoretical Physics (KITP). The SPT is supported by the NSF through grant no. OPP-1852617. This work was partially supported by the Center for AstroPhysical Surveys (CAPS) at the National Center for Supercomputing Applications (NCSA), University of Illinois Urbana-Champaign. D.Z., S.C.C., R.H. and G.C.P.W. acknowledge support from NSERC-6740. M. Aravena is supported by FONDECYT grant no. 1252054 and acknowledges support from the ANID Basal Project FB210003 and ANID MILENIO NCN2024_112. M.S. was financially supported by Becas-ANID scholarship #21221511 and also acknowledges support from ANID BASAL project FB210003.

Author information

Authors and Affiliations

  1. Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia, Canada

    Dazhi Zhou, Scott C. Chapman, Ryley Hill, Vismaya R. Pillai & George C. P. Wang

  2. Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, Canada

    Scott C. Chapman

  3. National Research Council, Herzberg Astronomy and Astrophysics, Victoria, British Columbia, Canada

    Scott C. Chapman

  4. Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Santiago, Chile

    Manuel Aravena & Manuel Solimano

  5. Millenium Nucleus for Galaxies (MINGAL), Santiago, Chile

    Manuel Aravena & Manuel Solimano

  6. Departamento de Astronomia, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, Cidade Universitária, São Paulo, Brazil

    Pablo Araya-Araya

  7. Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL, USA

    Melanie Archipley

  8. Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL, USA

    Melanie Archipley

  9. Department of Astronomy, University of Florida, Gainesville, FL, USA

    Jared Cathey

  10. Wits Centre for Astrophysics, School of Physics, University of the Witwatersrand, Johannesburg, South Africa

    Roger P. Deane

  11. Department of Physics, University of Pretoria, Hatfield, South Africa

    Roger P. Deane

  12. Kapteyn Astronomical Institute, University of Groningen, Groningen, The Netherlands

    Luca Di Mascolo

  13. Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire, Lagrange, France

    Luca Di Mascolo

  14. Instituto de Física, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile

    Raphael Gobat

  15. Cosmic Dawn Center (DAWN), Copenhagen, Denmark

    Thomas R. Greve

  16. DTU Space, Technical University of Denmark, Copenhagen, Denmark

    Thomas R. Greve

  17. Department of Astronomy, University of Illinois, Urbana, IL, USA

    Seonwoo Kim, Kedar A. Phadke, Veronica J. Dike, Joaquin D. Vieira & David Vizgan

  18. Center for AstroPhysical Surveys, National Center for Supercomputing Applications, Urbana, IL, USA

    Kedar A. Phadke & Joaquin D. Vieira

  19. NSF-Simons AI Institute for the Sky (SkAI), Chicago, IL, USA

    Kedar A. Phadke

  20. Department of Physics and Astronomy and George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX, USA

    Ana C. Posses & Justin S. Spilker

  21. School of Physics, University of Melbourne, Parkville, Victoria, Australia

    Christian L. Reichardt

  22. Max-Planck-Institut für Radioastronomie, Bonn, Germany

    Nikolaus Sulzenauer & Axel Weiß

  23. Department of Physics, University of Illinois, Urbana, IL, USA

    Joaquin D. Vieira

Authors
  1. Dazhi Zhou
    View author publications

    Search author on:PubMed Google Scholar

  2. Scott C. Chapman
    View author publications

    Search author on:PubMed Google Scholar

  3. Manuel Aravena
    View author publications

    Search author on:PubMed Google Scholar

  4. Pablo Araya-Araya
    View author publications

    Search author on:PubMed Google Scholar

  5. Melanie Archipley
    View author publications

    Search author on:PubMed Google Scholar

  6. Jared Cathey
    View author publications

    Search author on:PubMed Google Scholar

  7. Roger P. Deane
    View author publications

    Search author on:PubMed Google Scholar

  8. Luca Di Mascolo
    View author publications

    Search author on:PubMed Google Scholar

  9. Raphael Gobat
    View author publications

    Search author on:PubMed Google Scholar

  10. Thomas R. Greve
    View author publications

    Search author on:PubMed Google Scholar

  11. Ryley Hill
    View author publications

    Search author on:PubMed Google Scholar

  12. Seonwoo Kim
    View author publications

    Search author on:PubMed Google Scholar

  13. Kedar A. Phadke
    View author publications

    Search author on:PubMed Google Scholar

  14. Vismaya R. Pillai
    View author publications

    Search author on:PubMed Google Scholar

  15. Ana C. Posses
    View author publications

    Search author on:PubMed Google Scholar

  16. Christian L. Reichardt
    View author publications

    Search author on:PubMed Google Scholar

  17. Manuel Solimano
    View author publications

    Search author on:PubMed Google Scholar

  18. Justin S. Spilker
    View author publications

    Search author on:PubMed Google Scholar

  19. Nikolaus Sulzenauer
    View author publications

    Search author on:PubMed Google Scholar

  20. Veronica J. Dike
    View author publications

    Search author on:PubMed Google Scholar

  21. Joaquin D. Vieira
    View author publications

    Search author on:PubMed Google Scholar

  22. David Vizgan
    View author publications

    Search author on:PubMed Google Scholar

  23. George C. P. Wang
    View author publications

    Search author on:PubMed Google Scholar

  24. Axel Weiß
    View author publications

    Search author on:PubMed Google Scholar

Contributions

D.Z. reduced and analysed the data, interpreted the results, produced the figures and drafted the paper. S.C.C. conceived, designed and supervised the projects. R.G. produced the tSZ model of SPT2349–56 for the ALMA proposal. R.D. and R.G. validated the fidelity of the tSZ decrement. P.A.-A. calculated the redshift-evolution of the Compton-Y parameter and hot-gas fraction from TNG-Cluster simulations. S.K. reduced the JWST NIRCam data. D.Z., S.C.C., M. Aravena, P.A.-A., M. Archipley, J.C., R.D., L.D.M., R.G., T.R.G., R.H., S.K., K.A.P., V.R.P., A.C.P., C.R., M.S., J.S.S., N.S., V.J.D., J.D.V., D.V., G.C.P.W. and A.W. contributed substantially to discussing the results and preparing the paper.

Corresponding author

Correspondence to Dazhi Zhou.

Ethics declarations

Competing interests

The authors declare no competing interests.

Peer review

Peer review information

Nature thanks the anonymous reviewers for their contribution to the peer review of this work. Peer reviewer reports are available.

Additional information

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Extended data figures and tables

Extended Data Fig. 1 RGB image of the protocluster core.

The zoomed-in version of Fig. 1. The positions of submillimeter-luminous protocluster galaxies are indicated by their alphabetical names based on their rank-ordered 850 μm flux densities in Ref. 8. Three radio-loud AGN (A, C, and E) are highlighted with their names in red. Due to the crowdedness of the protocluster core, labels of faint members with a negligible 3 mm flux density are hidden in this figure for clarity.

Extended Data Fig. 2 ALMA high-resolution continuum map with the tSZ contours.

The solid contours are tSZ signal from  −2σ to  −8σ with steps of  −1σ. The dashed contours indicate regions with values above 2σ. The number labels on sources are IDs from the continuum source catalog in Extended Data Table 1. The primary beam responses are indicated as dotted lines. The synthesized beams of the continuum image (‘ALMA high-res’) and the SZ decrement (‘SZ’) are indicated in the upper-left and the bottom-left corners, respectively.

Extended Data Fig. 3 ALMA low-resolution tSZ map.

The solid contours are tSZ signal from  −2σ to  −8σ with steps of  −1σ. The dashed contours indicate regions with pixel values above 2σ. The primary beam responses are indicated as dotted lines. The synthesized beam of the SZ decrement is indicated in the bottom-left corner.

Extended Data Fig. 4 Curve-of-growth analysis for the tSZ decrement.

The flux density of the tSZ decrement and the flux-scaled synthesized beam of the ‘SZ’ map are indicated as the red solid and the blue dashed line, respectively. The overdensity radii are also shown as black dotted lines. The turnover in the decrement at radii ≳ 25″ may indicate dirty-beam sidelobes from an imperfect CLEANing process.

Extended Data Fig. 5 uv profile of the original and continuum subtracted data.

The real part of the averaged amplitude measured from the continuum-subtracted measurement sets as a function of uv-distance with uv bins of 3kλ. The errorbars are derived from visibility weightings. The negative signal becomes stronger at a shorter uv distance, suggesting that the tSZ decrement can be limited by the uv-coverage of the ACA and ALMA observations.

Extended Data Fig. 6 Compton-y map with dust continuum contours.

The solid contours are 3 mm continuum emission drawn at [2.5σ, 5σ, 10σ, 20σ, 40σ, 80σ] from the ‘ALMA high-res’ map. The primary beam responses are indicated at dotted lines. The synthesized beams of 3 mm continuum and Compton-y map are indicated in the upper-left and the bottom-left corners.

Extended Data Fig. 7 Compton-Y parameter Y500 as a function of halo mass M500 within R500.

The halo masses M500 and Compton-Y parameters Y500 are the same as in Fig. 2. The self-similar redshift evolution has been taken into account by multiplying Y500 by E(z)−2/3. The dashed line shows the universal M500 − Y500 relation25.

Extended Data Fig. 8 Halo mass as a function of ICM temperature.

The coloured curves show combinations of halo mass M200 and mass-weighted ICM temperature ⟨T200⟩ that reproduce the observed tSZ decrement for different assumed ICM fractions (from 0.02 to 0.10, as labelled). The corresponding ICM mass MICM is indicated in the top axis. The sub-virialized (blue) and super-virialized (red) regions are separated by the virialized temperature for different M200. The dotted line indicates the dynamical mass of SPT2349−5616. The light hatched band denotes the possible MICM range allowed by the universal baryonic fraction fb = 0.155. Without assuming an extreme ICM fraction fICM, either a more massive virialized halo or a super-virialized ICM gas is necessary to match the observed tSZ decrement.

Extended Data Fig. 9 Cosmic evolution of the hot gas (>107 K) fraction in galaxy clusters.

The fraction of hot ICM (Mhot ICM,500/M500) within r500 as a function of redshift obtained from the TNG-Cluster simulation. Based on the total mass M200 at z = 0, the clusters are placed in three mass bins, high mass (M200 > 1015 M⊙, black solid line), intermediate mass (5 × 1014 M⊙ < M200 < 1015 M⊙, red dashed line), and low mass (M200 < 5 × 1014 M⊙, orange dash-dotted line). The corresponding shaded regions represent the values between the 16th and 84th percentiles in individual mass bins.

Extended Data Table 1 3-mm continuum source catalog
Full size table

Supplementary information

Supplementary Information

This file contains Supplementary Methods, Figs. 1–5, Tables 1–3, and references.

Peer Review File

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Zhou, D., Chapman, S.C., Aravena, M. et al. Sunyaev–Zeldovich detection of hot intracluster gas at redshift 4.3. Nature 649, 1130–1133 (2026). https://doi.org/10.1038/s41586-025-09901-3

Download citation

  • Received:

  • Accepted:

  • Published:

  • Version of record:

  • Issue date:

  • DOI: https://doi.org/10.1038/s41586-025-09901-3

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing