Radio view of the Peanut cluster: merger-induced stripping and a radio halo shortly after pericentric passage

@misc{rajpurohit2026radio,
  title = {{Radio view of the Peanut cluster: merger-induced stripping and a radio halo shortly after pericentric passage}},
  author = {K. Rajpurohit and N. Lyskova and E. Churazov and W. Forman and I. Khabibullin and R. Kraft and L. Di Mascolo and T. Mroczkowski and A. Botteon and C. Jones and E. O'Sullivan and C. Zhang and R. J. van Weeren and I. Zhuravleva and G. Schellenberger and J. M. Vrtilek and L. P. David and R. Sunyaev and M. Devlin and S. Dicker and S. Haridas and J. van Marrewijk and B. S. Mason and E. Moravec and J. Orlowski-Scherer and C. Romero and C. L. Sarazin and J. Sievers},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.34667},
  eprint = {2610.34667},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.34667},
}

TY  - UNPB
TI  - Radio view of the Peanut cluster: merger-induced stripping and a radio halo shortly after pericentric passage
AU  - K. Rajpurohit
AU  - N. Lyskova
AU  - E. Churazov
AU  - W. Forman
AU  - I. Khabibullin
AU  - R. Kraft
AU  - L. Di Mascolo
AU  - T. Mroczkowski
AU  - A. Botteon
AU  - C. Jones
AU  - E. O'Sullivan
AU  - C. Zhang
AU  - R. J. van Weeren
AU  - I. Zhuravleva
AU  - G. Schellenberger
AU  - J. M. Vrtilek
AU  - L. P. David
AU  - R. Sunyaev
AU  - M. Devlin
AU  - S. Dicker
AU  - S. Haridas
AU  - J. van Marrewijk
AU  - B. S. Mason
AU  - E. Moravec
AU  - J. Orlowski-Scherer
AU  - C. Romero
AU  - C. L. Sarazin
AU  - J. Sievers
PY  - 2026
DA  - 2026/10/26
PB  - arXiv
DO  - 10.48550/arxiv.2610.34667
UR  - https://arxiv.org/abs/2610.34667
AB  - The Peanut galaxy cluster (SRGe CL0238.3+2005) offers a rare opportunity to investigate thermal and nonthermal processes only ∼0.1\,Gyr after pericentric passage. We present a multi-frequency radio study of this system at z=0.42 using new MeerKAT and uGMRT observations, complemented by Chandra and MUSTANG-2 data. We identify two morphologically and spectrally distinct radio components: a double-lobed source in the northern subcluster and extended diffuse emission across the cluster center. The double-lobed source has a strongly curved, ultra-steep spectrum and is offset by ∼22\,kpc from the nearest brightest cluster galaxy. Its spectral curvature and positional offset are consistent with remnant AGN plasma that may have been displaced during the merger or reshaped by a shock. The diffuse emission extends over ∼1~Mpc and is classified as an ultra-steep spectrum (α=−1.77±0.11 between 400\,MHz and 1.28\,GHz) radio halo. Its volume-averaged radio emissivity, (1.1±0.1)×10^−41 erg s^−1 cm^−3 Hz^−1 at 1.4\,GHz, is an order of magnitude higher than the characteristic value for other halos. The radial profile of the halo is well described by a single exponential fit and its radio emission correlates tightly with the X-ray, with a best-fit slope of 1.11±0.05. Chandra and MUSTANG-2 observations reveal candidate surface brightness discontinuities, with the most prominent inner feature coinciding with a region of flatter spectral index, potentially tracing localized particle (re)-acceleration. The coexistence of an extended ultra-steep spectrum radio halo, high radio emissivity, remnant AGN plasma, and candidate X-ray/SZ discontinuities makes the Peanut cluster an important test case for understanding the evolution of diffuse radio emission and its connection to the dynamical state of the intracluster medium in early-stage mergers.
ER  -