The thermal and non-thermal components within and between galaxy clusters Abell 399 and Abell 401

Federico Radiconi, Valentina Vacca, Elia Battistelli, Annalisa Bonafede, Valentina Capalbo, Mark J. Devlin, Luca Di Mascolo, Luigina Feretti, Patricio A. Gallardo, Ajay Gill, Gabriele Giovannini, Federica Govoni, Yilun Guan, Matt Hilton, Adam D. Hincks, John P. Hughes, Marco Iacobelli, Giovanni Isopi, Francesca Loi, Kavilan MoodleyTony Mroczkowski, Matteo Murgia, Emanuela Orrú, Rosita Paladino, Bruce Partridge, Craig L. Sarazin, Jack Orlowski Scherer, Cristóbal Sifón, Cristian Vargas, Franco Vazza, Edward J. Wollack

Research output: Contribution to journalArticlepeer-review


We measure the local correlation between radio emission and Compton-y signal across two galaxy clusters, Abell 399 and Abell 401, using maps from the Low Frequency Array and the Atacama Cosmology Telescope + Planck. These data sets allow us to make the first measurement of this kind at ∼arcmin resolution. We find that the radio brightness scales as Fradio y1.5 for Abell 401 and Fradio y2.8 for Abell 399. Furthermore, using XMM-Newton data, we derive a sublinear correlation between radio and X-ray brightness for both the clusters (Fradio} ∝ FX0.7). Finally, we correlate the Compton-y and X-ray data, finding that an isothermal model is consistent with the cluster profiles, y ∝ FX0.5. By adopting an isothermal-β model, we are able, for the first time, to jointly use radio, X-ray, and Compton-y data to estimate the scaling index for the magnetic field profile, B(r) ne(r)η in the injection and re-acceleration scenarios. Applying this model, we find that the combined radio and Compton-y signal exhibits a significantly tighter correlation with the X-ray across the clusters than when the data sets are independently correlated. We find η ∼0.6-0.8. These results are consistent with the upper limit we derive for the scaling index of the magnetic field using rotation measure values for two radio galaxies in Abell 401. We also measure the radio, Compton-y, and X-ray correlations in the filament between the clusters but conclude that deeper data are required for a convincing determination of the correlations in the filament.

Original languageEnglish (US)
Pages (from-to)5232-5246
Number of pages15
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Dec 1 2022

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • galaxies: clusters: individual: Abell 399, Abell 401
  • galaxies: clusters: intracluster medium
  • radiation mechanisms: non-thermal
  • radiation mechanisms: thermal


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