Particle streaming - Is the Alfven velocity the ultimate speed limit

Holman, Gordon D.; Ionson, J. A.; Scott, J. S.

doi:10.1086/156881

Cited by 62 publications

(44 citation statements)

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“…There are also other suggested radio halo formation scenarios: radio halos were proposed to be superpositions of large numbers of relic radio galaxies (Harris & Miley 1978, and others), they were proposed to be due to rapidly diffusing electrons escaping from radio galaxies (Holman et al 1979, and others), and their relativistic electrons were proposed to result from annihilation of neutralinos, if neutralinos are the dominant dark matter component (Colafrancesco & Mele 2001). Although these are interesting possibilities, they are disfavoured by the apparent association of radio halos with merger shock waves as discussed above.…”

Section: Halo Formation Scenariosmentioning

confidence: 99%

The radio luminosity function of cluster radio halos

Enßlin

Roettgering²

2002

A&A

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Abstract. A significant fraction of galaxy clusters exhibits cluster-wide radio halos. We give a simple prediction of the local and higher redshift radio halo luminosity function (RHLF) on the basis of (i) an observed and a theoretical X-ray cluster luminosity function (XCLF) (ii) the observed radio-X-ray luminosity correlation (RXLC) of galaxy clusters with radio halos (iii) an assumed fraction of f rh ≈ 1 3 galaxy clusters to have radio halos as supported by observations. We then find 300-700 radio halos with S 1.4 GHz > 1 mJy, and 10 5 -10 6 radio halos with S 1.4 GHz > 1 µJy should be visible on the sky. 14% of the S 1.4 GHz > 1 mJy and 56% of the S 1.4 GHz > 1 µJy halos are located at z > 0.3. Subsequently, we give more realistic predictions taking into account (iv) a refined estimate of the radio halo fraction as a function of redshift and cluster mass, and (v) a decrease in intrinsic radio halo luminosity with redshift due to increased inverse Compton electron energy losses on the Cosmic Microwave Background (CMB). We find that this reduces the radio halo counts from the simple prediction by only 30 % totally, but the high redshift (z > 0.3) counts are more strongly reduced by 50-70%. These calculations show that the new generation of sensitive radio telescopes, including LOFAR, ATA, EVLA, SKA and the already-operating GMRT should be able to detect large numbers of radio halos and will provide unique information for studies of galaxy cluster merger rates and associated non-thermal processes.

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Section: Halo Formation Scenariosmentioning

confidence: 99%

The radio luminosity function of cluster radio halos

Enßlin

Roettgering²

2002

A&A

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“…The passage of the shock is expected to generate turbulence downstream which will scatter the particles. Scattering upstream, however, is more problematic [Holman, Ionson, and Scott, 1979]. Observations [Tsurutani andRodriquez, 1981] of interplantetary shocks andplanetarybow shocksshowthat whenthey arenearlyparallel thereis a veryturbulentforeshock regioncapable of scattering particles.…”

Section: A Stochastic Accelerationmentioning

confidence: 99%

Particle acceleration in solar flares

Mandzhavidze

Ramaty

1993

Nuclear Physics B - Proceedings Supplements

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“…The passage of the 39 shock is expected to generate turbulence downstream which will scatter the particles. Scattering upstream, however,is more problematic (Holman, Ionson and Scott 1979). Observations (Tsurutani and Rodriquez 1981) of interplantetary shocks and planetary bow shocks show that when they are nearly parallel there is a very turbulent foresh rick reqion capable of scattering particles.…”

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confidence: 99%