A MeerKAT-meets-LOFAR study of MS 1455.0 + 2232: a 590 kiloparsec ‘mini’-halo in a sloshing cool-core cluster
| Autor: | C J Riseley, K Rajpurohit, F Loi, A Botteon, R Timmerman, N Biava, A Bonafede, E Bonnassieux, G Brunetti, T Enßlin, G Di Gennaro, A Ignesti, T Shimwell, C Stuardi, T Vernstrom, R J van Weeren |
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| Rok vydání: | 2022 |
| Předmět: |
High Energy Astrophysical Phenomena (astro-ph.HE)
Galaxies - clusters - individual - MS 1455.0+2232 Space and Planetary Science FOS: Physical sciences Radio continuum - general Astronomy and Astrophysics Astrophysics::Cosmology and Extragalactic Astrophysics Galaxies - clusters - general X-rays - galaxies - clusters Astrophysics - High Energy Astrophysical Phenomena Galaxies - clusters - intracluster medium Astrophysics::Galaxy Astrophysics |
| Zdroj: | Monthly Notices of the Royal Astronomical Society, 512(3), 4210-4230 |
| ISSN: | 1365-2966 0035-8711 |
| DOI: | 10.1093/mnras/stac672 |
| Popis: | Radio mini-haloes are poorly-understood, moderately-extended diffuse radio sources that trace the presence of magnetic fields and relativistic electrons on scales of hundreds of kiloparsecs, predominantly in relaxed clusters. With relatively few confirmed detections to-date, many questions remain unanswered. This paper presents new radio observations of the galaxy cluster MS1455.0$+$2232 performed with MeerKAT (covering the frequency range 872$-$1712 MHz) and LOFAR (covering 120$-$168 MHz), the first results from a homogeneously selected mini-halo census. We find that this mini-halo extends for $\sim590$ kpc at 1283 MHz, significantly larger than previously believed, and has a flatter spectral index ($\alpha = -0.97 \pm 0.05$) than typically expected. Our X-ray analysis clearly reveals a large-scale (254 kpc) sloshing spiral in the intracluster medium. We perform a point-to-point analysis, finding a tight single correlation between radio and X-ray surface brightness with a super-linear slope of $b_{\rm 1283~MHz} = 1.16^{+0.06}_{-0.07}$ and $b_{\rm 145~MHz} = 1.15^{+0.09}_{-0.08}$; this indicates a strong link between the thermal and non-thermal components of the intracluster medium. Conversely, in the spectral index/X-ray surface brightness plane, we find that regions inside and outside the sloshing spiral follow different correlations. We find compelling evidence for multiple sub-components in this mini-halo for the first time. While both the turbulent (re-)acceleration and hadronic scenarios are able to explain some observed properties of the mini-halo in MS1455.0$+$2232, neither scenario is able to account for all the evidence presented by our analysis. Comment: Accepted for publication in MNRAS. Manuscript contains 22 pages, 12 figures, 4 tables |
| Databáze: | OpenAIRE |
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