The correlation between radio power and Mach number for radio relics in galaxy clusters

Colafrancesco, S.; Marchegiani, ¶.; Paulo, C. M.

doi:10.1093/mnras/stx1806

Cited by 17 publications

(12 citation statements)

References 82 publications

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“…considering DSA mechanism (Colafrancesco et al 2017;Blandford et al 1987). This gives a shock speed of 1769 ± 148 359 km s −1 in a medium with temperature of about 3.5 × 10 7 K (as seen in Pearce et al 2017).…”

Section: Relic B a High Speed Second Internal Shockmentioning

confidence: 99%

Low-frequency radio study of MACS clusters at 610 and 235 MHz using the GMRT

Paul

Salunkhe

Datta

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Studies have shown that mergers of massive galaxy clusters produce shocks and turbulence in the intra-cluster medium, the possible event that creates radio relics, as well as the radio halos. Here we present GMRT dual-band (235 and 610 MHz) radio observations of four such clusters from the MAssive Cluster Survey (MACS) catalogue. We report the discovery of a very faint, diffuse, elongated radio source with a projected size of about 0.5 Mpc in cluster MACSJ0152.5-2852. We also confirm the presence of a radio relic-like source (about 0.4 Mpc, previously reported at 325 MHz) in MACSJ0025.4-1222 cluster. Proposed relics in both these clusters are found apparently inside the virial radius instead of their usual peripheral location, while no radio halos are detected. These high-redshift clusters (z = 0.584 and 0.413) are among the earliest merging systems detected with cluster radio emissions. In MACSJ1931-2635 cluster, we found a radio mini-halo and an interesting highly bent pair of radio jets. Further, we present here a maiden study of low frequency (GMRT 235 & 610 MHz) spectral and morphological signatures of a previously known radio cluster MACSJ0014.3-3022 (Abell 2744). This cluster hosts a relatively flat spectrum (α 610 235 ∼ −1.15), giant (∼ 1.6 Mpc each) halo-relic structure and a close-by high-speed (1769± 148 359 km s −1 ) mergershock (M = 2.02± 0.17 0.41 ) originated from a possible second merger in the cluster.

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Section: Relic B a High Speed Second Internal Shockmentioning

confidence: 99%

Low-frequency radio study of MACS clusters at 610 and 235 MHz using the GMRT

Paul

Salunkhe

Datta

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…The diffuse radio emission associated with the relics, detected at the peripheries in some merging galaxy clusters, is nevertheless explained via acceleration of CR particles in such low Mach-number shocks (e.g., Kang, Ryu & Jones 2017;van Weeren et al 2017). The low-M shocks have been routinely identified in the galaxy clusters via X-ray and radio emission (Colafrancesco, Marchegiani & Paulo 2017 and references therein). The observed spectral indices of the RMH are typically found between 1.2 and 1.6 (Giacintucci et al 2014;Kale et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Role of intracluster supernovae in radio mini-haloes in galaxy clusters

Omar

2019

Monthly Notices of the Royal Astronomical Society: Letters

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A possibility of generating a population of cosmic-ray particles accelerated in supernovae type-Ia (SNIa) remnants in the intracluster medium (ICM) is discussed. The presently constrained host-less SNIa rates in the clusters are found to be sufficient to fill a few hundred kpc region with cosmic-ray electrons within their typical synchrotron life-time of 100 Myr. The SNIa have already been considered potential sources of excess Fe abundance in cool-core clusters, distributed heating and turbulence in ICM. A good fraction of total radio power from mini-halos can be sourced from the SNIa energy deposited in the ICM with required energy conversion efficiency ≤ 1 per cent. The radio power estimated from low Mach-number shock acceleration in SNIa remnants is consistent with the observations within the uncertainties in the estimates. Some observational properties of the radio mini-halos are broadly consistent with the SNIa scenario. It is also speculated that radio powers and possibly detections of mini-halos are linked to star formation and merger histories of the clusters.

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“…Using the relation of Mach number and the spectral index i.e. mechanism; seeBlandford et al 1987;Colafrancesco et al 2017), we computed the average Mach number of the shock as M = 2.31 +0.50 −0.27 (using the average spectral index of α 1.4GHz 144MHz = −0.96 ± 0.17) for the proposed relic.…”

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confidence: 99%

Radio relic and the diffuse emission trail discovered in low-mass galaxy cluster Abell 1697

Paul

Salunkhe

Sonkamble

et al. 2020

A&A

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We report the discovery of a putative radio relic, 830 kpc in length and found toward the outskirts of galaxy cluster Abell 1697 (z = 0.181), using the LOFAR Two Meter Sky Survey (LoTSS) at 144 MHz. With an X-ray-inferred mass of M X−ray 500 = 2.9 +0.8 −0.7 × 10 14 M , this places Abell 1697 among the least massive relic hosts. The relic is also detected at 325 MHz in the Westerbork Northern Sky Survey (WENSS) and at 1.4 GHz in the NRAO VLA Sky Survey (NVSS) with an average spectral index of α(144, 325, 1400 MHz) = −0.98 ± 0.01 and magnetic field of B eq ∼ 0.6 µG. This relic, located in the northeast periphery of the cluster, is 300 kpc wide, exhibits a gradual spectral steepening across the width (α 1.4GHz 144MHz (in j) = −0.70 ± 0.11 to α 1.4GHz 144MHz (edge) = −1.19 ± 0.15), as well as indications of a co-spatial X-ray (ROSAT) shock and the radio relic emission. The radio power of the relic is P 1.4GHz = 8.5 ± 1.1 × 10 23 W Hz −1 , which is found to be in good agreement with the expected empirical correlation between the radio power and Largest Linear Size (LLS) of relics. The relic is trailed by extended (790 × 550 kpc) diffuse radio emission towards the cluster center, that is likely an ultra-steep spectrum (α 1.4GHz 144MHz < −1.84) radio source. This structure is also found to be older by at least 190 Myrs, has a very low surface brightness of 0.3 µJy arcsec −2 and magnetic field B eq ∼ 0.8 µG, similar to that of a radio phoenix. Finally, we discuss the possible mechanisms responsible for the relic and the trailing diffuse radio emission, invoking re-acceleration due to wake turbulence, as well as the revival of fossil electrons from an old AGN activity by the cluster merger shocks.

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The correlation between radio power and Mach number for radio relics in galaxy clusters

Cited by 17 publications

References 82 publications

Low-frequency radio study of MACS clusters at 610 and 235 MHz using the GMRT

Low-frequency radio study of MACS clusters at 610 and 235 MHz using the GMRT

Role of intracluster supernovae in radio mini-haloes in galaxy clusters

Radio relic and the diffuse emission trail discovered in low-mass galaxy cluster Abell 1697

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