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A universal correlation between warm and hot gas in the stripped tails of cluster galaxies


The impact of ram pressure stripping on galaxy evolution is well known (for example, ref. 1). Recent multi-wavelength data have revealed many examples of galaxies undergoing stripping, often accompanied with multi-phase tails2,3,4,5,6,7,8,9,10,11,12,13. As energy transfer in the multi-phase medium is an outstanding question in astrophysics, galaxies in stripping are great objects to study. Despite the recent burst of observational evidence, the relationship between gas in different phases in the tails is poorly known. Here we report a strong linear correlation between the X-ray surface brightness and the Hα surface brightness of the diffuse gas in the stripped tails at ~10–40 kpc scales, with a slope of ~3.5. This discovery provides evidence for the mixing of the stripped interstellar medium with the hot intra-cluster medium as the origin of the multi-phase tails. The established relation in stripped tails, also in comparison with the probably related correlations in similar environments such as galactic winds and X-ray cool cores, provides an important test for models of energy transfer in the multi-phase gas. It also indicates the importance of the Hα data to study clumping and turbulence in the intra-cluster medium.

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Fig. 1: Hα–X-ray SB correlation for diffuse gas in stripped tails.
Fig. 2: The Hα–X-ray correlation for ESO 137-001’s tail with the brightest X-ray and Hα emission.

Data availability

The X-ray and optical data that support the plots within this paper and other findings of this study are either publicly released (Chandra, XMM-Newton and Very Large Telescope/MUSE data) or published (narrow-band imaging data), as shown in Supplementary Table 2. The key results of this work (X-ray and Hα SB in tail regions) are also attached as an online table. Other results and reduced images of this work are available from the corresponding author M.S. upon reasonable request. Source data are provided with this paper.

Code availability

The software to reduce the X-ray and optical data in this work is publicly released. Upon request, the corresponding author M.S. will provide the code (Python and Wip) used to produce the figures.


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M.S. thanks A. Fabian, Y. Li, S. Tonnesen and D. Wang for helpful discussions. We thank T. Edge and S. Laudari for work on the FIR data and the Hubble Space Telescope data. Support for this work was provided by the National Aeronautics and Space Administration (NASA) through Chandra Award Numbers GO6-17127X and GO6-17111X issued by the Chandra X-ray Center, which is operated by the Smithsonian Astrophysical Observatory for and on behalf of NASA under contract NAS8-03060. Support for this work was also provided by NASA grant 80NSSC19K0953 and the National Science Foundation grant 1714764. P.J. acknowledges support from the project EU-ARC.CZ (LM2018106) of the Ministry of Education, Youth and Sports of the Czech Republic. M.F. acknowledges support from the European Research Council (grant agreement no. 757535). This research has made use of data obtained from the Chandra Data Archive and the Chandra Source Catalog and software provided by the Chandra X-ray Center in the application packages CIAO. This research is also based on observations obtained with XMM-Newton, a European Space Agency science mission with instruments and contributions directly funded by European Space Agency Member States and NASA. This research is also based on observations collected at the European Southern Observatory under programmes 60.A-9349(A), 60.A-9100(G), 095.A-0512(A), 096.B-0019(A), 098.B-0020(A), 0103.A-0684(A) and 0104.A-0226(A). This research is based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. We are honoured and grateful for the opportunity of observing the Universe from Maunakea, which has cultural, historical and natural significance in Hawaii.

Author information

Authors and Affiliations



M.S. initiated the research, led the Chandra and XMM-Newton proposals and the MUSE proposals on ESO 137-001, analysed the Chandra data, assisted with the MUSE data analysis and wrote the manuscript. C.G. analysed the XMM-Newton data and R.L. analysed the MUSE data from ESO 137-001 and D100. Both contributed to the writing of the manuscript. P.J. is the PI of the MUSE proposal on the Coma galaxies. G.G. is the PI of the MUSE proposal on the A1367 galaxies. M.F. analysed the MUSE data for A1367 galaxies. M.Y., M.F., G.G., A.B. and M.Y. provided the narrow-band Hα imaging data. All authors contribute to the discussion and interpretation of the results.

Corresponding authors

Correspondence to Ming Sun, Chong Ge or Rongxin Luo.

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Peer review information Nature Astronomy thanks Florence Durret and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary text, Figures 1–17, Tables 1–3 and references.

Source data

Source Data Fig. 1

Surface brightness data for Fig. 1.

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Sun, M., Ge, C., Luo, R. et al. A universal correlation between warm and hot gas in the stripped tails of cluster galaxies. Nat Astron 6, 270–274 (2022).

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