A merger mystery: no extended radio emission in the merging cluster Abell 2146

Russell, H. R.; Weeren, R. J. van; Edge, A. C.; McNamara, B. R.; Sanders, J. S.; Fabian, A. C.; Baum, S. A.; Canning, R. E. A.; Donahue, M.; O’Dea, C. P.

doi:10.1111/j.1745-3933.2011.01098.x

Cited by 64 publications

(55 citation statements)

References 62 publications

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“…The existence of massive and merging systems without RHs is well known (Cassano et al 2010Russell et al 2011). If RHs are due to turbulence acceleration of relativistic electrons during cluster mergers they should have a typical lifetime of ∼1 Gyr (see Brunetti et al 2009), which is of the same order of the merger timescale.…”

Section: Radio Halo-cluster Merger Connectionmentioning

confidence: 96%

Occurrence of radio halos in galaxy clusters

Cuciti

Cassano

Brunetti

et al. 2015

A&A

110

139

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Context. Giant radio halos (RH) are diffuse Mpc-scale synchrotron sources detected in some massive and merging galaxy clusters. An unbiased study of the statistical properties of RHs is crucial to constraining their origin and evolution. Aims. We investigate the occurrence of RHs and its dependence on the cluster mass in a Sunyaev-Zel'dovich (SZ)-selected sample of galaxy clusters, which is nearly a mass-selected sample. Moreover, we analyse the connection between RHs and merging clusters. Methods. We selected from the Planck SZ catalogue clusters with M ≥ 6 × 10 14 M at z = 0.08−0.33 and we searched for the presence of RHs using the NVSS for z < 0.2 and the GMRT RH survey (GRHS) and its extension (EGRHS) for 0.2 < z < 0.33. We used archival Chandra X-ray data to derive information on the dynamical status of the clusters. Results. We confirm that RH clusters are merging systems while the majority of clusters without RH are relaxed, thus supporting the idea that mergers play a fundamental role in the generation of RHs. We find evidence for an increase in the fraction of clusters with RHs with the cluster mass and this is in line with expectations derived on the basis of the turbulence re-acceleration scenario. Finally, we discuss the effect of the incompleteness of our sample on this result.

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Section: Radio Halo-cluster Merger Connectionmentioning

confidence: 96%

Occurrence of radio halos in galaxy clusters

Cuciti

Cassano

Brunetti

et al. 2015

A&A

110

139

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“…If turbulence plays a role in the acceleration and dynamics of relativistic particles radio haloes evolve on a time scale of about 1 Gyr. According to this scenario, the possibility of generating a halo that is sufficiently luminous (detectable by our observations) at the GMRT frequencies depends on the combination of several parameters, including the magnetic field properties of the hosting cluster, the mass of the merging systems, the fraction of the energy of mergers that is drained in turbulence (and its properties), and the stage of the merger Russell et al 2011;Donnert et al 2013;Brunetti & Jones 2014, for a review). Further statistical studies that also consider information on the mass of clusters will be very useful.…”

Section: Cluster Dynamics In Grhs and Egrhsmentioning

confidence: 99%

The Extended GMRT Radio Halo Survey

Kale¹,

Venturi²,

Giacintucci³

et al. 2015

A&A

134

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The intra-cluster medium contains cosmic rays and magnetic fields that are manifested through the large scale synchrotron sources, termed radio haloes, relics, and mini-haloes. The Extended Giant Metrewave Radio Telescope (GMRT) Radio Halo Survey (EGRHS) is an extension of the GMRT Radio Halo Survey (GRHS) designed to search for radio haloes using GMRT 610/235 MHz observations. The GRHS and EGRHS consists of 64 clusters in the redshift range 0.2−0.4 that have an X-ray luminosity larger than 5 × 10 44 erg s −1 in the 0.1−2.4 keV band and declination, δ > −31 • in the REFLEX and eBCS X-ray cluster catalogues. In this second paper in the series, GMRT 610/235 MHz data on the last batch of 11 galaxy clusters and the statistical analysis of the full sample are presented. A new mini-halo in RX J2129.6+0005 and candidate diffuse sources in Z5247, A2552, and Z1953 have been discovered. A unique feature of this survey are the upper limits on the detections of 1 Mpc sized radio haloes; 4 new are presented here, making a total of 31 in the survey. Of the sample, 58 clusters with adequately sensitive radio information were used to obtain the most accurate occurrence fractions so far. The occurrence fractions of radio haloes, mini-haloes and relics in our sample are ∼22%, ∼16% and ∼5%, respectively. The P 1.4 GHz − L X diagrams for the radio haloes and mini-haloes are presented. The morphological estimators -centroid shift (w), concentration parameter (c), and power ratios (P 3 /P 0 ) derived from the Chandra X-ray images -are used as proxies for the dynamical states of the GRHS and EGRHS clusters. The clusters with radio haloes and mini-haloes occupy distinct quadrants in the c− w, c− P 3 /P 0 and w− P 3 /P 0 planes, corresponding to the more and less morphological disturbance, respectively. The non-detections span both the quadrants.Key words. galaxies: clusters: general -radio continuum: galaxies IntroductionThe intra-cluster medium (ICM) is the diffuse matter that pervades the space between the galaxies in galaxy clusters. It is dominated by hot (∼10 7 −10 8 K) thermal plasma that emits thermal Bremsstrahlung that is detectable in soft X-ray bands and is also responsible for the thermal Sunyaev-Zel'dovich (SZ) effect. It has been found that the ICM also contains magnetic fields (0.1−1 μG) and relativistic electrons (Lorentz factors 1000) distributed over the entire cluster volume. The most direct evidence of this are the cluster-wide diffuse synchrotron sources detected in radio bands (see Feretti et al. 2012;Brunetti & Jones 2014, for reviews). They occur in a variety of morphologies and sizes and are classified into three main types, namely, radio haloes, radio relics, and mini-haloes.Radio haloes (RHs) are Mpc-sized sources found in massive, merging galaxy clusters. They typically trace the morphology of the X-ray surface brightness, show negligible polarisation, and Appendices are available in electronic form at http://www.aanda.org have synchrotron spectral indices 1 , α ≥ 1. The emitting relativistic electro...

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“…Donnert et al 2013). The non detection of a radio halo for A2146 by Russell et al (2011) might therefore indicate that this cluster fits well into this aged population. However, this is inconsistent with the X-ray observations since the estimated age from the shock fronts puts the cluster at an evolutionary stage of 0.2 − 0.3 Gyr after core passage (see Russell et al 2010White et al 2015), similar to the Bullet cluster, yet the Bullet cluster clearly sits along the correlation.…”

Section: Introductionmentioning

confidence: 99%

“…Using 5.7 hours of observations from the Giant MetreWave Telescope (GMRT) at 325 MHz, Russell et al (2011) found no evidence of extended radio emission in A2146 down to a rms of 250 µJy beam −1 . The only two radio sources detected coincided with A2146-A and a second cluster galaxy to the north (labelled as radio source in Fig.…”

Section: Introductionmentioning

confidence: 99%

Mystery solved: discovery of extended radio emission in the merging galaxy cluster Abell 2146

Hlavacek-Larrondo

Gendron-Marsolais

Fecteau-Beaucage

et al. 2017

Monthly Notices of the Royal Astronomical Society

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Abell 2146 (z = 0.232) is a massive galaxy cluster currently undergoing a spectacular merger in the plane of the sky with a bullet-like morphology. It was the first system in which both the bow and upstream shock fronts were detected at X-ray wavelengths (Mach ∼ 2), yet deep GMRT 325 MHz observations failed to detect extended radio emission associated with the cluster as is typically seen in such systems. We present new, multi-configuration 1 − 2 GHz Karl G. Jansky Very Large Array (VLA) observations of Abell 2146 totalling 16 hours of observations. These data reveal for the first time the presence of an extended (≈ 850 kpc), faint radio structure associated with Abell 2146. The structure appears to harbour multiple components, one associated with the upstream shock which we classify as a radio relic and one associated with the subcluster core which is consisted as being a radio halo bounded by the bow shock. The newly detected structures have some of the lowest radio powers detected thus far in any cluster (P 1.4GHz, halo = 2.4 ± 0.2 × 10 23 W Hz −1 and P 1.4GHz, relic = 2.2 ± 0.2 × 10 23 W Hz −1 ). The flux measurement of the halo, as well as its morphology, also suggest that the halo was recently created (≈ 0.3 Gyr after core passage), consistent with the dynamical state of the cluster. These observations demonstrate the capacity of the upgraded VLA to detect extremely faint and extended radio structures. Based on these observations, we predict that many more radio relics and radio halos in merging clusters should be detected by future radio facilities such as the Square Kilometre Array (SKA).

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A merger mystery: no extended radio emission in the merging cluster Abell 2146

Cited by 64 publications

References 62 publications

Occurrence of radio halos in galaxy clusters

Occurrence of radio halos in galaxy clusters

The Extended GMRT Radio Halo Survey

Mystery solved: discovery of extended radio emission in the merging galaxy cluster Abell 2146

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