Optical/X-ray/radio view of Abell 1213: A galaxy cluster with anomalous diffuse radio emission

Journal Article · Fri Apr 21 00:00:00 EDT 2023 · Astronomy and Astrophysics

DOI:https://doi.org/10.1051/0004-6361/202345842· OSTI ID:2425246

Boschin, W. ^[1]; Girardi, M. ^[2]; De Grandi, S. ^[3]; Riva, G. ^[4]; Feretti, L. ^[5]; Giovannini, G. ^[6]; Govoni, F. ^[7]; Vacca, V. ^[7]

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1. Istituto Nazionale di Astrofisica (INAF), Canary Islands (Spain); Instituto de Astrofísica de Canarias, Canary Islands (Spain); Univ. de La Laguna, Canary Islands (Spain)
2. Univ. of Trieste (Italy); Istituto Nazionale di Astrofisica (INAF), Trieste (Italy). Osservatorio Astronomico di Trieste
3. Istituto Nazionale di Astrofisica (INAF), Merate (Italy). Osservatorio Astronomico di Brera
4. Istituto Nazionale di Astrofisica (INAF), Milano (Italy). Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano; Università degli Studi di Milano (Italy)
5. Istituto Nazionale di Astrofisica (INAF), Bologna (Italy). Istituto di Radioastronomia
6. Istituto Nazionale di Astrofisica (INAF), Bologna (Italy). Istituto di Radioastronomia; Univ. of Bologna (Italy)
7. Istituto Nazionale di Astrofisica (INAF), Selargius (Italy). Osservatorio Astronomico di Cagliari

Context. Abell 1213, a low-richness galaxy system, is known to host an anomalous radio halo detected in data of the Very Large Array (VLA). It is an outlier with regard to the relation between the radio halo power and the X-ray luminosity of the parent clusters. Aims. Our aim is to analyze the cluster in the optical, X-ray, and radio bands to characterize the environment of its diffuse radio emission and to shed new light on its nature. Methods. We used optical data from the Sloan Digital Sky Survey to study the internal dynamics of the cluster. We also analyzed archival XMM-Newton X-ray data to unveil the properties of its hot intracluster medium. Finally, we used recent data from the LOw Frequency ARray (LOFAR) at 144 MHz, together with VLA data at 1.4 GHz, to study the spectral behavior of the diffuse radio source. Results. Both our optical and X-ray analysis reveal that this low-mass cluster exhibits disturbed dynamics. In fact, it is composed of several galaxy groups in the peripheral regions and, in particular, in the core, where we find evidence of substructures oriented in the NE–SW direction, with hints of a merger nearly along the line of sight. The analysis of the X-ray emission adds further evidence that the cluster is in an unrelaxed dynamical state. At radio wavelengths, the LOFAR data show that the diffuse emission is ~510 kpc in size. Moreover, there are hints of low-surface-brightness emission permeating the cluster center. Conclusions. The environment of the diffuse radio emission is not what we would expect for a classical halo. The spectral index map of the radio source is compatible with a relic interpretation, possibly due to a merger in the N–S or NE–SW directions, in agreement with the substructures detected through the optical analysis. The fragmented, diffuse radio emissions at the cluster center could be attributed to the surface brightness peaks of a faint central radio halo.

• Research Organization: US Department of Energy (USDOE), Washington, DC (United States). Office of Science, Sloan Digital Sky Survey (SDSS)
• Sponsoring Organization: USDOE Office of Science (SC)
• OSTI ID: 2425246
• Journal Information: Astronomy and Astrophysics, Journal Name: Astronomy and Astrophysics Vol. 672; ISSN 0004-6361
• Publisher: EDP Sciences
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
Galaxy: kinematics and dynamics
acceleration of particles
galaxies: clusters: general
galaxies: clusters: individual: Abell 1213
galaxies: clusters: intracluster medium
large-scale structure of Universe