Measuring the Temperature of Extremely Hot Shock-heated Gas in the Major Merger MACS J0717.5+3745 with Relativistic Corrections to the Sunyaev–Zel'dovich Effect

Abstract

Copyright and License

© 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

The authors sincerely thank I. Valtchanov for his assistance in designing, executing, and understanding the SPIRE-FTS observations as our “Friend of the Observer” many years ago.

This work has been supported in part by the National Aeronautics and Space Administration under grants NAS7-03001-1467865, 80NSSC19K1018, and 80NSSC24K1024 and by the National Science Foundation under grants DGE-1745301 and NSF/AST-2206082. L.L. acknowledges support from INAF grant 1.05.24.05.15. The authors acknowledge Research Computing at the Rochester Institute of Technology for providing computational resources and support that have contributed to the research results reported in this publication.

The scientific results reported in this article are based in part on observations made with Herschel, a European Space Agency Cornerstone Mission with significant participation by NASA. HIPE is a joint development by the Herschel Science Ground Segment Consortium, consisting of ESA, the NASA Herschel Science Center, and the HIFI, PACS, and SPIRE consortia. This research has made use of the NASA/IPAC Infrared Science Archive, which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology.

Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

The scientific results reported in this article are based in part on work at the Caltech Submillimeter Observatory, which is operated by the California Institute of Technology.

The scientific results reported in this article are based in part on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.

This paper employs a dataset, obtained by the Chandra X-ray Observatory, contained in the Chandra Data Collection doi:10.25574/cdc.548.

Facilities

Herschel - European Space Agency's Herschel space observatory, CSO - Caltech Submillimeter Observatory, XMM - Newton X-Ray Multimirror Mission satellite, CXO - Chandra X-ray Observatory satellite, Keck I, keck II - .

Software References

astropy, (Astropy Collaboration et al. 2013, 2018, 2022), SZpack (J. Chluba et al. 2012, 2013), emcee (D. Foreman-Mackey et al. 2013), PCAT (R. M. Feder et al. 2023), scipy (P. Virtanen et al. 2020), Xspec (K. Arnaud et al. 1999), Numpy (C. R. Harris et al. 2020), contbin (J. S. Sanders 2016), HIPE (S. Ott 2010), matplotlib (J. D. Hunter 2007), LMC.