Particle reacceleration in the Coma cluster: radio properties and hard X-ray emission

Brunetti, G.; Setti, G.; Feretti, L.; Giovannini, G.

doi:10.1046/j.1365-8711.2001.03978.x

Cited by 476 publications

(602 citation statements)

References 48 publications

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“…This steep-spectrum region may indicate a decline of the magnetic field or a significant steepening of the particle spectrum (Brunetti et al 2001). However, it could also be that this steepening is due to electron energy losses downstream of relicE.…”

Section: Radio Halo Spectral Index Variationsmentioning

confidence: 99%

“…In the secondary (or hadronic) model, the CR electrons are secondary products of collisions between thermal ions and relativistic protons in the ICM (e.g., Dennison 1980;Blasi & Colafrancesco 1999;Dolag & Enßlin 2000;Miniati et al 2001;Pfrommer & Enßlin 2004;Pfrommer et al 2008;Keshet & Loeb 2010;Enßlin et al 2011;Zandanel et al 2014). In the turbulent re-acceleration model, electrons are re-accelerated by merger induced magnetohydrodynamical turbulence (e.g., Schlickeiser et al 1987;Brunetti et al 2001;Petrosian 2001;Pinzke et al 2015). Secondary models are challenged by the large energy content of cosmic ray protons needed to explain radio halos with very steep spectra (Brunetti 2004;Brunetti et al 2008) and by the non-detection of γ-rays (e.g., Jeltema & Profumo 2011;Brunetti et al 2012;Ackermann et al 2014).…”

Section: Introductionmentioning

confidence: 99%

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Lofar, Vla, and Chandra Observations of the Toothbrush Galaxy Cluster

Weeren

Brunetti

Brüggen

et al. 2016

ApJ

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161

212

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We present deep LOFAR observations between 120 and 181 MHz of the "Toothbrush" (RX J0603.3+4214), a cluster that contains one of the brightest radio relic sources known. Our LOFAR observations exploit a new and novel calibration scheme to probe 10 times deeper than any previous study in this relatively unexplored part of the spectrum. The LOFAR observations, when combined with VLA, GMRT, and Chandra X-ray data, provide new information about the nature of cluster merger shocks and their role in re-accelerating relativistic particles. We derive a spectral index of 0.8 0.1 a = - at the northern edge of the main radio relic, steepening toward the south to 2 a » -. The spectral index of the radio halo is remarkably uniform ( 1.16 a = -, with an intrinsic scatter of 0.04  ). The observed radio relic spectral index gives a Mach number of 2.8 0.3 0.5  = -+ , assuming diffusive shock acceleration. However, the gas density jump at the northern edge of the large radio relic implies a much weaker shock ( 1.2  » , with an upper limit of 1.5  » ). The discrepancy between the Mach numbers calculated from the radio and X-rays can be explained if either (i) the relic traces a complex shock surface along the line of sight, or (ii) if the radio relic emission is produced by a re-accelerated population of fossil particles from a radio galaxy. Our results highlight the need for additional theoretical work and numerical simulations of particle acceleration and reacceleration at cluster merger shocks.

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Section: Radio Halo Spectral Index Variationsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Lofar, Vla, and Chandra Observations of the Toothbrush Galaxy Cluster

Weeren

Brunetti

Brüggen

et al. 2016

ApJ

Self Cite

161

212

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“…The interpretation of the polarization map is presented Sections 5.2.1-5.2.4. In the turbulent reacceleration model, electrons are reaccelerated via magnetohydrodynamical turbulence (e.g., Schlickeiser et al 1987;Brunetti et al 2001;Petrosian 2001). In this case, spectral index variations across radio halos should be related to underlying spatial variations in the turbulent energy and magnetic field strength (Feretti et al 2004;Orrú et al 2007;Vacca et al 2014).…”

Section: S-band Polarization Mapmentioning

confidence: 99%

VLA Radio Observations of the HST Frontier Fields Cluster Abell 2744: The Discovery of New Radio Relics

Pearce

Weeren

Andrade-Santos

et al. 2017

ApJ

117

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Cluster mergers leave distinct signatures in the intracluster medium (ICM) in the form of shocks and diffuse cluster radio sources that provide evidence for the acceleration of relativistic particles. However, the physics of particle acceleration in the ICM is still not fully understood. Here we present new 1-4 GHz Jansky Very Large Array (VLA) and archival Chandra observations of the HST Frontier Fields Cluster Abell2744. In our new VLA images, we detect the previously known ∼2.1Mpc radio halo and ∼1.5Mpc radio relic. We carry out a radio spectral analysis from which we determine the relic's injection spectral index to be a = - 1.12 0. 0.31 under the assumption of diffusive shock acceleration. We also find evidence for spectral steepening in the post-shock region. We do not find evidence for a significant correlation between the radio halo's spectral index and ICM temperature. In addition, we observe three new polarized diffuse sources and determine two of these to be newly discovered giant radio relics. These two relics are located in the southeastern and northwestern outskirts of the cluster. The corresponding integrated spectral indices measure −1.81±0.26 and −0.63±0.21 for the SE and NW relics, respectively. From an X-ray surface brightness profile we also detect a possible density jump of = -+ R 1.39 0.22 0.34 co-located with the newly discovered SE relic. This density jump would correspond to a shock front Mach number of  = -+ 1.26 0.15 0.25 .

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“…This mechanism of turbulence (re)acceleration (e.g. Brunetti et al 2001;Fujita et al 2003;Brunetti et al 2004) is now believed to be the source of relativistic electrons associated with the giant radio halos observed in a growing number of massive clusters with recent merger activity such as Coma (e.g. Feretti & Giovannini 2008;Ferrari et al 2008, for reviews).…”

Section: What Is the Origin Of The Radio Emission?mentioning

confidence: 99%

A pan-chromatic view of the galaxy cluster XMMU J1230.3+1339 atz= 0.975

Fassbender

Böhringer

Santos

et al. 2011

A&A

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Context. Observations of the formation and evolution of massive galaxy clusters and their matter components provide crucial constraints on cosmic structure formation, the thermal history of the intracluster medium (ICM), galaxy evolution, transformation processes, and gravitational and hydrodynamic interaction physics of the subcomponents. Aims. We characterize the global multi-wavelength properties of the X-ray selected galaxy cluster XMMU J1230.3+1339 at z = 0.975, a new system discovered within the XMM-Newton Distant Cluster Project (XDCP). We measure and compare various widely used mass proxies and identify multiple cluster-associated components from the inner core region out to the large-scale structure environment.Methods. We present a comprehensive galaxy cluster study based on a joint analysis of X-ray data, optical imaging and spectroscopy observations, weak lensing results, and radio properties for achieving a detailed multi-component view on a system at z ∼ 1. Results. We find an optically very rich and massive system with M 200 (4.2 ± 0.8) × 10 14 M , T X,2500 5.3 +0.7 −0.6 keV, and L bol X,500 (6.5 ± 0.7) × 10 44 erg s −1 . We have identified a central fly-through group close to core passage and find marginally extended 1.4 GHz radio emission possibly associated with the turbulent wake region of the merging event. On the cluster outskirts we see evidence for an on-axis infalling group with a second brightest cluster galaxy (BCG) and indications for an additional off-axis group accretion event. We trace two galaxy filaments beyond the nominal cluster radius and provide a tentative reconstruction of the 3D-accretion geometry of the system. Conclusions. In terms of total mass, ICM structure, optical richness, and the presence of two dominant BCG-type galaxies, the newly confirmed cluster XMMU J1230.3+1339 is likely the progenitor of a system very similar to the local Coma cluster, differing by 7.6 Gyr of structure evolution. This new system is an ideally suited astrophysical model laboratory for in-depth follow-up studies on the aggregation of baryons in the cold and hot phases.

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Particle reacceleration in the Coma cluster: radio properties and hard X-ray emission

Cited by 476 publications

References 48 publications

Lofar, Vla, and Chandra Observations of the Toothbrush Galaxy Cluster

Lofar, Vla, and Chandra Observations of the Toothbrush Galaxy Cluster

VLA Radio Observations of the HST Frontier Fields Cluster Abell 2744: The Discovery of New Radio Relics

A pan-chromatic view of the galaxy cluster XMMU J1230.3+1339 atz= 0.975

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