The LOFAR and JVLA view of the distant steep spectrum radio halo in MACS J1149.5+2223

Bruno, L.; Rajpurohit, K.; Brunetti, G.; Gastaldello, F.; Botteon, A.; Ignesti, Alessandro; Bonafede, A.; Dallacasa, D.; Cassano, R.; Weeren, R. J. van; Cuciti, V.; Gennaro, G. Di; Shimwell, T. W.; Brüggen, M.

doi:10.1051/0004-6361/202039877

Cited by 31 publications

(36 citation statements)

References 108 publications

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“…This is largely consistent with the USSRH population (e.g. Cassano et al, 2013;Bruno et al, 2021;Duchesne et al, 2021a) which are normally found to be under-luminous with respect to the 1400 MHz scaling relations but shift towards the regression line when the relation is computed at 150 MHz. Conversely, the candidate halo (or point source) in Abell 2693 sits far above both relations, though the derived mass approaches the limits obtainable with RASS and carries significant uncertainty.…”

Section: Low Frequency Radio Halos and Relicssupporting

confidence: 85%

“…Panoramic Survey Telescope And Rapid Response System RASS data shown in the Fig. 3(iii) indicates the bulk ICM sits to the southwest, with D1 oriented almost perpendicular, which is abnormal for large-scale relics (with the exception of the relic source in MACS J1149.5+2223, though the nature of that source is unclear; Bonafede et al 2012;Bruno et al 2021). With no evidence of shocks (and an absence of more sensitive X-ray data) we cannot differentiate from relic or fossil electrons/remnant radio galaxy.…”

Section: Röentgen Satellitementioning

confidence: 99%

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Low-frequency integrated radio spectra of diffuse, steep-spectrum sources in galaxy clusters: palaeontology with the MWA and ASKAP

Duchesne,

Johnston-Hollitt,

Bartalucci

2021

Preprint

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Galaxy clusters have been found to host a range of diffuse, non-thermal emission components, generally with steep, power law spectra. In this work we report on the detection and follow-up of radio halos, relics, remnant radio galaxies, and other fossil radio plasmas in Southern Sky galaxy clusters using the Murchison Widefield Array, Australian Square Kilometre Array Pathfinder. We make use of the frequency coverage between the two radio interferometers-from 88 to ∼ 900 MHz-to characterise the integrated spectra of these sources within this frequency range. Highlights from the sample include the detection of a double relic system in Abell 3186, a mini-halo in RXC J0137.2−0912, a candidate halo and relic in Abell 3399, and a complex multi-episodic head-tail radio galaxy in Abell 3164. We compare this selection of sources and candidates to the literature sample, finding sources consistent with established radio power-cluster mass scaling relations. Finally, we use the low-frequency integrated spectral index, 𝛼 (𝑆 𝜈 ∝ 𝜈 𝛼 ), of the detected sample of cluster remnants and fossil sources to compare with samples of known halos, relics, remnants and fossils to investigate a possible link between their electron populations. We find the distributions of 𝛼 to be consistent with relic and halo emission generated by seed electrons that originated in fossil or remnant sources. However, the present sample sizes are insufficient to rule out other scenarios.

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Section: Low Frequency Radio Halos and Relicssupporting

confidence: 85%

Section: Röentgen Satellitementioning

confidence: 99%

Low-frequency integrated radio spectra of diffuse, steep-spectrum sources in galaxy clusters: palaeontology with the MWA and ASKAP

Duchesne,

Johnston-Hollitt,

Bartalucci

2021

Preprint

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“…b ∼ 0.64 − 1) regardless of the morphology of the radio halos (e.g. Feretti et al 2001;Govoni et al 2001a,b;Bruno et al 2021;Rajpurohit et al 2021;Botteon et al 2020b). Also, a lower value of b at higher frequency suggests additional non-thermal processes in the outer regions of the halo where X-ray emission is fainter.…”

Section: Thermal and Non-thermal Correlationmentioning

confidence: 99%

“…In this paper, we adopt a flux scale uncertainty of 10 percent on the LOFAR data as assumed by a number of previous studies (e.g. Bruno et al 2021;Rajpurohit et al 2021). beam uncorrected Notes: a : Briggs weighting, PA: position angle with the reference axis to the north and counter-clockwise as positive, c : smoothed.…”

Section: Observations and Data Reductionmentioning

confidence: 99%

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A 3.5 Mpc long radio relic in the galaxy cluster ClG 0217+70

Hoang

Zhang

Stuardi

et al. 2021

A&A

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Context. Megaparsec-scale radio sources in the form of halos and relics are often detected in dynamically disturbed galaxy clusters. Although they are associated with merger-induced turbulence and shocks, respectively, their formation is not fully understood. Aims. We aim to identify the mechanisms responsible for particle acceleration and magnetic field amplification in the halo and relics of the galaxy cluster ClG 0217+70. Methods. We observed ClG 0217+70 with LOFAR at 141 MHz and with VLA at 1.5 GHz, and we combined these observations with VLA 1.4 GHz archival data to study the morphological and spectral properties of the diffuse sources. We added Chandra archival data to examine the thermal and non-thermal properties of the halo. Results. Our LOFAR and VLA data confirm the presence of a giant radio halo in the cluster centre and multiple relics in the outskirts. The radio and X-ray emission from the halo are correlated, implying a tight relation between the thermal and non-thermal components. The diffuse radio structure in the south-east, with a projected size of 3.5 Mpc, is the most extended radio relic detected to date. The spectral index across the relic width steepens towards the cluster centre, suggesting electron ageing in the post-shock regions. The shock Mach numbers for the relics derived from the spectral index map range between 2.0 and 3.2. However, the integrated spectral indices lead to increasingly high Mach numbers for the relics farther from the cluster centre. This discrepancy could be because the relation between injection and integrated spectra does not hold for distant shocks, suggesting that the cooling time for the radio-emitting electrons is longer than the crossing time of the shocks. The variations in the surface brightness of the relics and the low Mach numbers imply that the radio-emitting electrons are re-accelerated from fossil plasma that could originate in active galactic nuclei.

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Low-frequency integrated radio spectra of diffuse, steep-spectrum sources in galaxy clusters: palaeontology with the MWA and ASKAP

Duchesne

Johnston‐Hollitt

Bartalucci

2021

Publ. Astron. Soc. Aust.

View full text Add to dashboard Cite

Galaxy clusters have been found to host a range of diffuse, non-thermal emission components, generally with steep, power law spectra. In this work we report on the detection and follow-up of radio halos, relics, remnant radio galaxies, and other fossil radio plasmas in Southern Sky galaxy clusters using the Murchison Widefield Array and the Australian Square Kilometre Array Pathfinder. We make use of the frequency coverage between the two radio interferometers—from 88 to $\sim\!900$ MHz—to characterise the integrated spectra of these sources within this frequency range. Highlights from the sample include the detection of a double relic system in Abell 3186, a mini-halo in RXC J0137.2–0912, a candidate halo and relic in Abell 3399, and a complex multi-episodic head-tail radio galaxy in Abell 3164. We compare this selection of sources and candidates to the literature sample, finding sources consistent with established radio power–cluster mass scaling relations. Finally, we use the low-frequency integrated spectral index, $\alpha$ ( $S_v \propto v^\alpha$ ), of the detected sample of cluster remnants and fossil sources to compare with samples of known halos, relics, remnants and fossils to investigate a possible link between their electron populations. We find the distributions of $\alpha$ to be consistent with relic and halo emission generated by seed electrons that originated in fossil or remnant sources. However, the present sample sizes are insufficient to rule out other scenarios.

show abstract

The LOFAR and JVLA view of the distant steep spectrum radio halo in MACS J1149.5+2223

Cited by 31 publications

References 108 publications

Low-frequency integrated radio spectra of diffuse, steep-spectrum sources in galaxy clusters: palaeontology with the MWA and ASKAP

Low-frequency integrated radio spectra of diffuse, steep-spectrum sources in galaxy clusters: palaeontology with the MWA and ASKAP

A 3.5 Mpc long radio relic in the galaxy cluster ClG 0217+70

Low-frequency integrated radio spectra of diffuse, steep-spectrum sources in galaxy clusters: palaeontology with the MWA and ASKAP

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