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Intracluster light is already abundant at redshift beyond unity


Intracluster light (ICL) is diffuse light from stars that are gravitationally bound not to individual member galaxies, but to the halo of galaxy clusters. Leading theories1,2 predict that the ICL fraction, defined by the ratio of the ICL to the total light, rapidly decreases with increasing redshift, to the level of a few per cent at z > 1. However, observational studies have remained inconclusive about the fraction beyond redshift unity because, to date, only two clusters in this redshift regime have been investigated. One shows a much lower fraction than the mean value at low redshift3, whereas the other possesses a fraction similar to the low-redshift value4. Here we report an ICL study of ten galaxy clusters at 1 z 2 based on deep infrared imaging data. Contrary to the leading theories, our study finds that ICL is already abundant at z 1, with a mean ICL fraction of approximately 17%. Moreover, no significant correlation between cluster mass and ICL fraction or between ICL colour and cluster-centric radius is observed. Our findings suggest that gradual stripping can no longer be the dominant mechanism of ICL formation. Instead, our study supports the scenario wherein the dominant ICL production occurs in tandem with the formation and growth of the brightest cluster galaxies and/or through the accretion of preprocessed stray stars.

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Fig. 1: BCG + ICL images of our ten z 1 clusters.
Fig. 2: BCG + ICL radial profiles.
Fig. 3: BCG + ICL radial colour profiles.
Fig. 4: ICL fraction evolution.

Data availability

The raw HST near-infrared imaging data used for the current study are publicly available. The processed imaging data are available on the github repository at data are provided with this paper.

Code availability

An exhaustive repository of code for our custom data processing and analyses reported in this manuscript are available on the github repository at


  1. Rudick, C. S., Mihos, J. C. & McBride, C. K. The quantity of intracluster light: comparing theoretical and observational measurement techniques using simulated clusters. Astrophys. J. 732, 48–64 (2011).

    Article  ADS  Google Scholar 

  2. Contini, E., De Lucia, G., Villalobos, Á. & Bogani, S. On the formation and physical properties of the intracluster light in hierarchical galaxy formation models. Mon. Not. R. Astron. Soc. 437, 3787–3802 (2014).

    Article  ADS  Google Scholar 

  3. Burke, C., Collins, C. A., Stott, J. P. & Hilton, M. Measurement of the intracluster at z ~ 1. Mon. Not. R. Astron. Soc. 425, 2058–2068 (2012).

    Article  ADS  Google Scholar 

  4. Ko, J. & Jee, M. J. Evidence for the existence of abundant intracluster light at z = 1.24. Astrophys. J. 862, 95–103 (2018).

    Article  ADS  Google Scholar 

  5. Montes, M. & Trujillo, I. Intracluster light at the Frontier - II. The Frontier Fields Clusters. Mon. Not. R. Astron. Soc. 474, 917–932 (2018).

    Article  ADS  CAS  Google Scholar 

  6. DeMaio, T. et al. The growth of brightest cluster galaxies and intracluster light over the past 10 billion years. Mon. Not. R. Astron. Soc. 491, 3751–3759 (2020).

    Article  ADS  CAS  Google Scholar 

  7. Gonzalez, A. H. et al. Galaxy cluster baryon fractions revisited. Astrophys. J. 778, 14–29 (2013).

    Article  ADS  Google Scholar 

  8. Presotto, V. et al. Intracluster light properties in the CLASH-VLT cluster MACS J1206.2-0847. Astron. Astrophys. 565, A126 (2014).

    Article  Google Scholar 

  9. Contini, E., Yi, S. K. & Kang, X. Theoretical predictions of colors and metallicity of the intracluster light. Astrophys. J. 871, 24–33 (2019).

    Article  ADS  CAS  Google Scholar 

  10. Burke, C., Hilton, M. & Collins, C. Coevolution of brightest cluster galaxies and intracluster light using CLASH. Mon. Not. R. Astron. Soc. 449, 2353–2367 (2015).

    Article  ADS  CAS  Google Scholar 

  11. Morishita, T. et al. Characterizing intracluster light in the Hubble Frontier Fields. Astrophys. J. 846, 139–151 (2017).

    Article  ADS  Google Scholar 

  12. Almao-Martinez, K. A. & Blakeslee, J. P. Specific frequencies and luminosity profiles of cluster galaxies and intracluster light in Abell 1689. Astrophys. J. 849, 6–24 (2017).

    Article  ADS  Google Scholar 

  13. Ellien, A. et al. The complex case of MACS J0717.5+6745 and its extended filament: intra-cluster light, galaxy luminosity function, and galaxy orientations. Astron. Astrophys. 628, A34 (2019).

    Article  CAS  Google Scholar 

  14. Feldmeier, J. J. et al. Intracluster planetary nebulae in the Virgo Cluster. III. Luminosity of the intracluster light and tests of the spatial distribution. Astrophys. J. 615, 196–208 (2004).

    Article  ADS  CAS  Google Scholar 

  15. Griffiths, A. et al. MUSE spectroscopy and deep observations of a unique compact JWST target, lensing cluster CLIO. Mon. Not. R. Astron. Soc. 475, 2853–2869 (2018).

    Article  ADS  CAS  Google Scholar 

  16. Jee, M. J. Tracing the peculiar dark matter structure in the galaxy cluster Cl 0024+17 with intracluster stars and gas. Astrophys. J. 717, 420–434 (2010).

    Article  ADS  CAS  Google Scholar 

  17. Jimenez-Teja, Y. et al. Unveiling the dynamical state of massive clusters through the ICL fraction. Astrophys. J. 857, 79–96 (2018).

    Article  ADS  Google Scholar 

  18. Jimenez-Teja, Y. et al. J-PLUS: analysis of the intracluster light in the Coma cluster. Astrophys. J. 522, A183 (2019).

    Google Scholar 

  19. Krick, J. E. & Berstein, R. A. Diffuse optical light in galaxy clusters. II. Correlations with cluster properties. Astrophys. J. 134, 466–493 (2007).

    Google Scholar 

  20. Mihos, J. C. Intragroup and intracluster light. in Proc. IAU Symp.: The General Assembly of Galaxy Halos: Structure, Origin and Evolution vol. 317 (eds Bragaglia, A., Arnaboldi, M., Rejkuba, M. & Romano, D.) 27–34 (Int. Astron. Union, 2015).

  21. Yoo, J. et al. Intracluster light properties in a fossil cluster at z = 0.47. Mon. Not. R. Astron. Soc. 508, 2634–2649 (2021).

    Article  ADS  CAS  Google Scholar 

  22. Montes, M. The faint light in groups and clusters of galaxies. Nature. Astro. 6, 308–316 (2022).

    Article  ADS  Google Scholar 

  23. Navarro, J. F., Frenck, C. S. & White, S. D. M. The structure of cold dark matter halos. Astrophys. J. 462, 563–575 (1996).

    Article  ADS  CAS  Google Scholar 

  24. Asensio, I. A. et al. The intracluster light as a tracer of the total matter density distribution: a view from simulations. Mon. Not. R. Astron. Soc. 494, 1859–1864 (2020).

    Article  ADS  CAS  Google Scholar 

  25. Pillepich, A. et al. First results from the IllustrisTNG simulations: the stellar mass content of groups and clusters of galaxies. Mon. Not. R. Astron. Soc. 475, 648–675 (2018).

    Article  ADS  CAS  Google Scholar 

  26. Murante, G. et al. The diffuse light in simulations of galaxy clusters. Astrophys. J. Lett. 607, 83–86 (2004).

    Article  ADS  Google Scholar 

  27. Purcell, C. W., Bullock, J. S. & Zentner, A. R. Shredded galaxies as the source of diffuse intrahalo light on varying scales. Astrophys. J. 666, 20–33 (2007).

    Article  ADS  CAS  Google Scholar 

  28. Furnell, K. E. et al. The growth of intracluster light in XCS-HSC galaxy clusters from 0.1 < z < 0.5. Mon. Not. R. Astron. Soc. 502, 2419–2437 (2021).

    Article  ADS  CAS  Google Scholar 

  29. Guennou, L. et al. Intracluster light in clusters of galaxies at redshifts 0.4 < z < 0.8. Astron. Astrophys. 537, A64 (2012).

    Article  Google Scholar 

  30. Contini, E. On the origin and evolution of the intra-cluster light: a brief review of the most recent developments. MDPI. 9, 60 (2021).

    Google Scholar 

  31. Murante, G. et al. The importance of mergers for the origin of intracluster stars in cosmological simulations of galaxy clusters. Mon. Not. R. Astron. Soc. 377, 2–16 (2007).

    Article  ADS  Google Scholar 

  32. Contini, E., Yi, S. K. & Kang, E. The different growth pathways of brightest cluster galaxies and intracluster light. Mon. Not. R. Astron. Soc. 479, 932–944 (2018).

    ADS  CAS  Google Scholar 

  33. Tang, L. et al. An investigation of intracluster light evolution using cosmological hydrodynamical simulations. Astrophys. J. 859, 85–97 (2018).

    Article  ADS  Google Scholar 

  34. DeMaio, T. et al. On the origin of the intracluster light in massive galaxy clusters. Mon. Not. R. Astron. Soc. 448, 1162–1177 (2015).

    Article  ADS  Google Scholar 

  35. DeMaio, T. et al. Lost but not forgotten: intracluster light in galaxy groups and clusters. Mon. Not. R. Astron. Soc. 474, 3009–3031 (2018).

    Article  ADS  CAS  Google Scholar 

  36. Sahu, K. WFC3 Data Handbook v.5.5 (STScI, 2021).

  37. Hoffmann, S. L. et al. The DrizzlePac Handbook v. 2.0 (STScI, 2021).

  38. Bertin, E. & Arnouts, S. SExtractor: software for source extraction. Astron. Astrophys. 117, 393–404 (1996).

    ADS  Google Scholar 

  39. Stone, C. J. et al. AutoProf - I. An automated non-parametric light profile pipeline for modern galaxy surveys. Mon. Not. R. Astron. Soc. 508, 1870–1887 (2021).

    Article  ADS  Google Scholar 

  40. Sérsic, J. L. Influence of the atmospheric and instrumental dispersion on the brightness distribution in a galaxy. Boletin de la Asociacion Argentina de Astronomia La Plata Argentina 6, 41–43 (1963).

    ADS  Google Scholar 

  41. Krist, J. Tiny Tim: an HST PSF simulator. Astronomical Data Analysis Software and Systems II. 52, 536 (1993).

    ADS  Google Scholar 

  42. Oser, L. et al. The two phases of galaxy formation. Astrophys. J. 725, 2312–2323 (2010).

    Article  ADS  CAS  Google Scholar 

  43. Huang, S. et al. The Carnegie-Irvine Galaxy Survey. III. The three-component structure of nearby elliptical galaxies. Astrophys. J. 766, 47 (2013).

    Article  ADS  Google Scholar 

  44. Huang, S. et al. The Carnegie-Irvine Galaxy Survey. IV. A method to determine the average mass ratio of mergers that built massive elliptical galaxies. Astrophys. J. 821, 114–133 (2016).

    Article  ADS  Google Scholar 

  45. Gill, J. Bayesian Methods: A Social Behavioral Science Approch 2nd edn (CRC, 2008).

  46. Balogh, M. L. et al. The GOGREEN and GCLASS surveys: first data release. Mon. Not. R. Astron. Soc. 500, 358–387 (2021).

    Article  ADS  CAS  Google Scholar 

  47. Santos, J. S. et al. Multiwavelength observations of a rich galaxy cluster at z ~ 1. The HST/ACS colour-magnitude diagram. Astron. Astrophys. 501, 49–60 (2009).

    Article  ADS  CAS  Google Scholar 

  48. Gongalez, A. H. et al. The massive and distant clusters of WISE Survey: MOO J1142+1527, a 1015 M galaxy cluster at z = 1.19. Astrophys. J. L. 812, L40 (2015).

    Article  ADS  Google Scholar 

  49. Demarco, R. et al. VLT and ACS observations of RDCS J1252.9-2927: dynamical structure and galaxy populations in a massive cluster at z = 1.237. Astrophys. J. 663, 164–182 (2007).

    Article  ADS  CAS  Google Scholar 

  50. Decker, B. et al. The massive and distant clusters of WISE Survey. VI. Stellar mass fractions of a sample of high-redshift infrared-selected clusters. Astrophys. J. 878, 72–84 (2019).

    Article  ADS  Google Scholar 

  51. Santos, J. S. et al. Dust-obscured star formation in the outskirts of XMMU J2235.3-2557, a massive galaxy cluster at z = 1.4. Mon. Not. R. Astron. Soc. 433, 1287–1299 (2013).

    Article  ADS  Google Scholar 

  52. Webb, T. M. A. et al. The star formation history of BCGs to z = 1.8 from the SpARCS/SWIRE Survey: evidence for significant in situ star formation at high redshift. Astrophys. J. 814, 96–107 (2015).

    Article  ADS  Google Scholar 

  53. Stanford, S. A. et al. IDCS J1426.5+3508: discovery of a massive, infrared-selected galaxy cluster at z = 1.75. Astrophys. J. 753, 164–171 (2012).

    Article  ADS  Google Scholar 

  54. Newman, A. B. et al. Spectroscopic confirmation of the rich z = 1.80 galaxy cluster JKCS 041 using the WFC3 grism: environmental trends in the ages and structure of quiescent galaxies. Astrophys. J. 788, 51–76 (2014).

    Article  ADS  Google Scholar 

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This study is based on observations created with NASA/ESA Hubble Space Telescope and downloaded from the Mikulski Archive for Space Telescope at the Space Telescope Science Institute. The current research is supported by the National Research Foundation of Korea under programme 2022R1A2C1003130 and the Yonsei Future-Leading Research Initiative programme.

Author information

Authors and Affiliations



M.J.J. conceived, designed and supervised the project. M.J.J. and H.J. analysed the Hubble Space Telescope imaging data, developed the pipeline, interpreted the results and wrote the manuscript.

Corresponding author

Correspondence to M. James Jee.

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The authors declare no competing interests.

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Nature thanks Emanuele Contini and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Extended data figures and tables

Extended Data Fig. 1 Definition of common sky areas.

(A) Exposure map for the single-frame image. (B) Same as (C) except that it is for the mosaic image. (C) Science image for single frame. (D) Same as (C) except that it is for the mosaic image. The pink circular region in (A) is the region that is observed in common by all contributing frames. (B) shows how this common region is positioned in one of the input frames. As the central region of this circle is likely to be heavily influenced by the ICL, we excluded the central region and instead defined the annulus shown in (C) and (D) to estimate the background level.

Extended Data Fig. 2 Masking size growth and impacts on background level.

(A), (B) and (C) illustrate our scheme for masking size growth from the original to the ce = 2 and ce = 6 cases. Note that we exhaust pixels for ICL measurement at ce = 6. In (D), we show how the background level (green) changes as we vary the masking size using the expansion coefficient for a single exposure. We observe that at ce 6 the measurement converges (red). The black solid line indicates the result when instead we use a 3σ clipping algorithm without considering the diffuse wings of the astronomical objects. The yellow line shows the surface brightness level measured at each ce. (E) is the same as the left except that the measurement is from the final deep stack. Solid lines indicate the median value and shaded regions show the 68% uncertainty. As the image is deeper, the number of pixels discarded (masked out) at the same ce value is much greater.

Extended Data Fig. 3 Schematic diagram of our ICL-oriented data reduction.

Dark grey rectangles show the steps where external packages are used, while light grey rectangles illustrate our custom procedures. Parallelograms represent the input/output data.

Extended Data Fig. 4 Red sequence selection scheme.

Here we display the case for SPT2106. (A) Colour–magnitude diagram. Black dots are all sources detected by SExtractor. The red dots represent the spectroscopic members, whereas the orange dots are our red sequence candidates. The BCG is indicated with a red star. The red dashed line shows the final, best-fit red sequence. The dot-dashed lines bracket the 68% distribution. (B) Distribution of the F105W < 26 object distances from the best-fit red sequence. The green line shows the best-fit double Gaussian models. The yellow line illustrates a single Gaussian component, which represents the distribution of the red sequence candidates.

Extended Data Fig. 5 Comparison between ICL fraction and cluster mass.

The mass comes from weak lensing studies. No significant correlation between ICL fraction and mass is found.

Extended Data Table 1 Target List
Extended Data Table 2 ICL fractions and impact of various systematics
Extended Data Table 3 Weak lensing mass, the number of spectroscopic member galaxies and their references

Source data

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Joo, H., Jee, M.J. Intracluster light is already abundant at redshift beyond unity. Nature 613, 37–41 (2023).

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