Galaxy cluster thermodynamics at z=1.7: Resolved tSZ and X-ray analysis of CL J0459.6-4946

@misc{marrewijk2026galaxy,
  title = {{Galaxy cluster thermodynamics at z=1.7: Resolved tSZ and X-ray analysis of CL J0459.6-4946}},
  author = {J. van Marrewijk and L. Di Mascolo and S. Ueda and T. Mroczkowski and T. Akahori and E. S. Battistelli and M. J. Devlin and A. Flores and A. S. Gill and F. A. Gómez and M. Hilton and J. P. Hughes and T. Kitayama and Y. -T. Lin and K. Moodley and N. Okabe and M. Pannella and B. Ried Guachalla and H. Röttgering and J. S. Sanders and A. Saro and C. Sifón and V. Strazzullo and M. Takizawa and E. J. Wollack and X. Zhang},
  howpublished = {arXiv},
  year = {2026},
  month = nov,
  doi = {10.48550/arxiv.2611.00132},
  eprint = {2611.00132},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2611.00132},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - Galaxy cluster thermodynamics at z=1.7: Resolved tSZ and X-ray analysis of CL J0459.6-4946
AU  - J. van Marrewijk
AU  - L. Di Mascolo
AU  - S. Ueda
AU  - T. Mroczkowski
AU  - T. Akahori
AU  - E. S. Battistelli
AU  - M. J. Devlin
AU  - A. Flores
AU  - A. S. Gill
AU  - F. A. Gómez
AU  - M. Hilton
AU  - J. P. Hughes
AU  - T. Kitayama
AU  - Y. -T. Lin
AU  - K. Moodley
AU  - N. Okabe
AU  - M. Pannella
AU  - B. Ried Guachalla
AU  - H. Röttgering
AU  - J. S. Sanders
AU  - A. Saro
AU  - C. Sifón
AU  - V. Strazzullo
AU  - M. Takizawa
AU  - E. J. Wollack
AU  - X. Zhang
PY  - 2026
DA  - 2026/11/01
PB  - arXiv
DO  - 10.48550/arxiv.2611.00132
UR  - https://arxiv.org/abs/2611.00132
AB  - Measurements of the entropy and temperature distribution of the intracluster medium (ICM) of local clusters have proven pivotal for the study of cluster astrophysics. Here, we extend these measurements to z=1.7 with a resolved analysis of the ICM in ACT/SPT-CL J0459.6-4946. By combining high-resolution thermal Sunyaev-Zeldovich measurements using new, deep ALMA Band 1 and 3 observations, with archival X-ray data, we conclude that the cluster has (i) an ICM with a flat and relatively high (≈ 200 keV cm^2) entropy distribution out to ≈ 0.3 r_500,c, (ii) a hot core (T_e ≃ 14 keV) with a declining temperature profile, (iii) a short effective path length along the line of sight of l_eff ≃ (0.75 ± 0.05) × r_500,c, and (iv) a clumpiness factor C = ⟨ n_e^2 ⟩ / ⟨ n_e ⟩^2 ≃ 1.17 ± 0.05 within r_500,c. Its dynamic nature and high redshift suggest that the cluster is still thermalising its ICM, consistent with a relatively large hydrostatic mass bias of b = 1 − M_500,c,HE/M_500,c,WL = 0.27^+0.32_−0.67 that we measure with respect to the weak lensing mass. Furthermore, a region with low entropy and high density to the south of the cluster centre is observed in the X-rays yet absent in the Compton-y map, indicating pressure equilibrium; we interpret this as a sloshing cold front -- the first such detection at high redshifts. This case study demonstrates that ≈ 3h-long ALMA observations, combined with comparatively "short" X-ray exposures (≈ 122 ks), can fully characterise the ICM at high redshift, opening a path towards the thermodynamics of young and distant galaxy clusters for larger samples.
ER  -