2025/01/13 by Andra Stroe, K. Rajpurohit, Kamlesh Rajpurohit +35 · 1 voice
Physics and Astronomy · #Astronomy and Astrophysical Research #Astrophysical Phenomena and Observations #Astrophysics of Galaxies (astro-ph.GA) #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #Gamma-ray bursts and supernovae #High Energy Astrophysical Phenomena (astro-ph.HE) #astro-ph.CO #astro-ph.GA #astro-ph.HE
paper · pdf · doi:10.48550/arxiv.2501.07651
openalex publication_date 2025/01/13 · arxiv published 2025/01/13 · arxiv updated 2025/02/13 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Relics are diffuse, highly-polarized radio sources that trace merger-driven shocks at the periphery of merging galaxy clusters. The LOFAR survey recently discovered a rare example of double relics in the low-mass cluster PSZ2 G181.06+48.47. Through a detailed exploration of new Chandra and XMM-Newton observations, we reveal that PSZ2 G181.06+48.47 has a lower mass (M500,X=2.32+0.29-0.25×1014 M\odot) than previously thought. Despite its cool global temperature of kT500=3.62+0.15-0.07 keV, PSZ2 G181.06+48.47 is one of the most disturbed clusters in the Planck sample, with a complex morphological and thermodynamic structure. We discover a set of three discontinuities within <500 kpc of the cluster center, and, from a surface brightness analysis, place 5σ upper limits of MNE<1.43 and MSW<1.57 for any shock associated with the relic locations. We also revise established scaling relations for double radio-relics by adding 12 new systems not included in previous work. The PSZ2 G181.06+48.47 relics have the widest separation (scaled for r500) of all known double-relic systems. The exceptional distance from the cluster center (>r200), indicates the relics may be associated with shocks in the ``run-away" phase. We propose that this late-stage, post-apocenter merger is captured as the two subclusters with a mass ratio of 1.2-1.4 fall back into each other. The outer relic shocks were likely produced at the first core passage, while the inner discontinuities are associated with the second infall.