A three-component giant radio halo: The puzzling case of the galaxy cluster Abell 2142

被引：15

作者：

Bruno L. ^{[1
,2
]}

Botteon A. ^{[2
]}

Shimwell T. ^{[3
,4
]}

Cuciti V. ^{[1
,2
,5
]}

De Gasperin F. ^{[2
,5
]}

Brunetti G. ^{[2
]}

Dallacasa D. ^{[1
,2
]}

Gastaldello F. ^{[6
]}

Rossetti M. ^{[6
]}

Van Weeren R.J. ^{[4
]}

Venturi T. ^{[2
]}

Russo S.A. ^{[7
]}

Taffoni G. ^{[7
]}

Cassano R. ^{[2
]}

Biava N. ^{[1
,2
]}

Lusetti G. ^{[5
]}

Bonafede A. ^{[1
,2
]}

Ghizzardi S. ^{[6
]}

De Grandi S. ^{[6
]}

机构：

[1] Dipartimento di Fisica e Astronomia (DIFA), Università di Bologna, Via Gobetti 93/2, Bologna

[2] Istituto Nazionale di Astrofisica (INAF) - Istituto di Radioastronomia (IRA), Via Gobetti 101, Bologna

[3] Astron, Netherlands Institute for Radio Astronomy, Oude Hoogeveensedijk 4, Dwingeloo

[4] Leiden Observatory, Leiden University, PO Box 9513, Leiden

[5] Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, Hamburg

[6] Inaf - Iasf Milano, Via A. Corti 12, Milano

[7] Istituto Nazionale di Astrofisica (INAF), Astronomical Observatory of Trieste, Trieste

来源：

Astronomy and Astrophysics | 2023年 / 678卷

基金：

爱尔兰科学基金会; 英国科研创新办公室; 英国科学技术设施理事会; 欧盟地平线“2020”; 欧洲研究理事会;

关键词：

Acceleration of particles; Galaxies: clusters: individual: Abell 2142; Galaxies: clusters: intracluster medium; Large-scale structure of Universe; Radiation mechanisms: non-thermal; Radiation mechanisms: thermal;

D O I：

10.1051/0004-6361/202347245

中图分类号：

TK1 [热力工程、热机];

学科分类号：

080702 ;

摘要：

Context. Turbulence introduced into the intracluster medium (ICM) through cluster-merger events transfers energy to non-thermal components, and can trigger the formation of diffuse synchrotron radio sources. Typical diffuse sources in the form of giant radio halos and mini-halos are found in merging and relaxed cool-core galaxy clusters, respectively. On the other hand, recent observations reveal an increasing complexity to the non-thermal phenomenology. Aims. Abell 2142 (A2142) is a mildly disturbed cluster that exhibits uncommon thermal and non-thermal properties. It is known to host a hybrid halo consisting of two components (H1 and H2), namely a mini-halo-like and an enigmatic elongated radio halo-like structure. We aim to investigate the properties, origin, and connections of each component. Methods. We present deep LOFAR observations of A2142 in the frequency ranges 30- 78 MHz and 120 - 168 MHz. With complementary multi-frequency radio and X-ray data, we analysed the radio spectral properties of the halo and assessed the connection between the non-thermal and thermal components of the ICM. Results. We detect a third radio component (H3), which extends over the cluster volume on scales of ~2 Mpc, embeds H1 and H2, and has a morphology that roughly follows the thermal ICM distribution. The radio spectral index is moderately steep in H1 (α=1.09 ± 0.02) and H2 (α=1.15 ± 0.02), but is steeper (α=1.57 ± 0.20) in H3. Our analysis of the thermal and non-thermal properties allowed us to discuss possible formation scenarios for each radio component. Turbulence from sloshing motions of low-entropy gas on different scales may be responsible for the origin of H1 and H2. We classified H3 as a giant ultrasteep spectrum radio halo, and find that it may trace the residual activity from an old energetic merger and/or inefficient turbulent reacceleration induced by ongoing minor mergers. © 2023 EDP Sciences. All rights reserved.

引用

共 144 条

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