| Title: |
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 |
| Authors: |
Vaughan, Benjamin J.; Sayers, Jack; Spencer, Locke; Swidinksi, Nicholas; Wills, Ryan; Zemcov, Michael; Arthur, Derek; Butler, Victoria; Feder, Richard M.; Klyde, Daniel; Lovisari, Lorenzo; Mantz, Adam; Silich, Emily M. |
| Source: |
Astrophysical Journal, 1000(1), 123, (2026-03-20) |
| Publisher Information: |
American Astronomical Society |
| Publication Year: |
2026 |
| Collection: |
Caltech Authors (California Institute of Technology) |
| Subject Terms: |
Galaxy clusters; Sunyaev-Zeldovich effect; Cosmology; X-ray astronomy; Intracluster medium; Extragalactic astronomy |
| Description: |
The conversion of gravitational potential to kinetic energy results in an intracluster medium (ICM) gas with a characteristic temperature near 10 keV in the most massive galaxy clusters. X-ray observations, primarily from Chandra and XMM-Newton, have revealed a wealth of information about the thermodynamics of this gas. However, two regimes remain difficult to study with current instruments: superheated gas well above 10 keV generated by shocks from major mergers, and distant systems strongly impacted by cosmological dimming. Relativistic corrections to the Sunyaev–Zel’dovich effect (rSZe) produce a fractional spectral distortion in the cosmic microwave background at submillimeter and millimeter wavelengths that could offer a complementary probe of both high-temperature and high-redshift ICM gas. Here we describe multiband measurements of the rSZe, including observations from the Fourier Transform Spectrometer on the Herschel-SPIRE instrument, that constrain the ICM thermodynamics of the major merger MACS J0717.5+3745. Within the seven observed lines of sight, we find an average temperature of T rSZe = 15.1_(−3.3)^(+3.8) keV, which is consistent with the values obtained from X-ray measurements of the same regions, with T Chandra = 18.0_(−1.1)^(+1.1) keV and T XMM = 13.9_(−0.9)^(+0.9) keV. This work demonstrates that the rSZe signal can be detected with moderate spectral resolution submillimeter data, while also establishing the utility of such measurements for probing superheated regions of the ICM. ; © 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. ; 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 ... |
| Document Type: |
article in journal/newspaper |
| Language: |
English |
| Relation: |
https://doi.org/10.25574/01655; https://arxiv.org/abs/arXiv:2510.08837; https://authors.library.caltech.edu/communities/caltechauthors/ |
| DOI: |
10.3847/1538-4357/ae4483 |
| Availability: |
https://doi.org/10.3847/1538-4357/ae4483 |
| Rights: |
info:eu-repo/semantics/openAccess ; Creative Commons Attribution 4.0 International ; https://creativecommons.org/licenses/by/4.0/legalcode |
| Accession Number: |
edsbas.929FBFEE |
| Database: |
BASE |