Signatures in a Giant Radio Galaxy of a Cosmological Shock Wave at Intersecting Filaments of Galaxies

Enßlin, T. A.; Simon, Patrick; Biermann, P. L.; Klein, U.; Kohle, S.; Kronberg, P. P.; Mack, K.‐H.

doi:10.1086/319131

Cited by 32 publications

(24 citation statements)

References 23 publications

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“…Indirect evidence of extracluster magnetic fields may exist in radio observations by Ensslin et al (2001) of the giant radio galaxy NGC 315. New images reveal significant asymmetries and peculiarities in this galaxy.…”

Section: E Extracluster Fieldsmentioning

confidence: 99%

Origin of galactic and extragalactic magnetic fields

2002

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A variety of observations suggest that magnetic fields are present in all galaxies and galaxy clusters. These fields are characterized by a modest strength (10 −7 − 10 −5 G) and huge spatial scale (< ∼ 1 Mpc). It is generally assumed that magnetic fields in spiral galaxies arise from the combined action of differential rotation and helical turbulence, a process known as the αω-dynamo. However fundamental questions concerning the nature of the dynamo as well as the origin of the seed fields necessary to prime it remain unclear. Moreover, the standard αω-dynamo does not explain the existence of magnetic fields in elliptical galaxies and clusters. The author summarizes what is known observationally about magnetic fields in galaxies, clusters, superclusters, and beyond. He then reviews the standard dynamo paradigm, the challenges that have been leveled against it, and several alternative scenarios. He concludes with a discussion of astrophysical and early Universe candidates for seed fields.

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Section: E Extracluster Fieldsmentioning

confidence: 99%

Origin of galactic and extragalactic magnetic fields

2002

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“…Miniati et al 2001b; Ryu et al 2003; Pfrommer et al 2006, 2007; Kang et al 2007; Hoeft et al 2008; Skillman et al 2008; Molnar et al 2009; Vazza, Brunetti & Gheller 2009a) or indirectly by the action of shock waves on radio plasma bubbles, employing a novel method of combining radio observations and analytical insight that is supported by idealized hydrodynamic simulations (e.g. Enßlin et al 2001; Pfrommer & Jones 2011). Most of these numerical works agree on the fact that the bulk of the energy in the Universe is dissipated at relatively weak shocks, M ∼ 2–3 (where M is the Mach number), internal to clusters, while strong and larger shocks are found outside large‐scale structures, M ∼ 10–100, at the boundary layers between the ‘collapsing’ and the ‘expanding’ universe.…”

Section: Introductionmentioning

confidence: 99%

A comparison of cosmological codes: properties of thermal gas and shock waves in large-scale structures

Vazza

Dolag

Ryu

et al. 2011

Monthly Notices of the Royal Astronomical Society

112

127

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Cosmological hydrodynamical simulations are a valuable tool for understanding the growth of large‐scale structure and the observables connected with this. Yet, comparably little attention has been given to validation studies of the properties of shocks and of the resulting thermal gas between different numerical methods – something of immediate importance as gravitational shocks are responsible for generating most of the entropy of the large‐scale structure in the Universe. Here, we present results for the statistics of thermal gas and the shock wave properties for a large volume simulated with three different cosmological numerical codes: the Eulerian total variations diminishing (TVD) code, the Eulerian piecewise parabolic method based code enzo and the Lagrangian smoothed particle hydrodynamics (SPH) code gadget. Starting from a shared set of initial conditions, we present convergence tests for a cosmological volume of side‐length 100 Mpc h−1, studying in detail the morphological and statistical properties of the thermal gas as a function of mass and spatial resolution in all codes. By applying shock‐finding methods to each code, we measure the statistics of shock waves and the related cosmic ray acceleration efficiencies, within the sample of simulations and for the results of the different approaches. We discuss the regimes of uncertainties and disagreement among codes, with a particular focus on the results at the scale of galaxy clusters. Even if the bulk of thermal and shock properties is reasonably in agreement among the three codes, yet some significant differences exist (especially between Eulerian methods and SPH). In particular, we report (a) differences of huge factors (∼10–100) in the values of average gas density, temperature, entropy, Mach number and shock thermal energy flux in the most rarefied regions of the simulations (ρ/ρcr < 1) between grid and SPH methods; (b) the hint of an entropy core inside clusters simulated in grid codes; (c) significantly different phase diagrams of shocked cells in grid codes compared to SPH and (d) sizable differences in the morphologies of accretion shocks between grid and SPH methods.

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“…Dietrich et al 2004; Drinkwater et al 2004; Ebeling, Barrett & Donovan 2004; Gal & Lubin 2004; Pimbblet & Drinkwater 2004, amongst others) and not only at optical wavelengths (e.g. Scharf et al 2000; Ensslin et al 2001; Tittley & Henriksen 2001; Bagchi et al 2002; Durret et al 2003); although detection of (X‐ray‐emitting gas from) filaments has not been without some failures (Briel & Henry 1995). One is left considering several questions: (i) how common are FOGs?…”

Section: Introductionmentioning

confidence: 99%

Intercluster filaments of galaxies programme: abundance and distribution of filaments in the 2dFGRS catalogue

Pimbblet

Drinkwater

Hawkrigg

2004

Monthly Notices of the Royal Astronomical Society

107

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Filaments of galaxies are known to stretch between galaxy clusters at all redshifts in a complex manner. In this Letter, we present an analysis of the frequency and distribution of intercluster galaxy filaments selected from the 2dF Galaxy Redshift Survey. Out of 805 cluster–cluster pairs, we find at least 40 per cent have bona fide filaments. We introduce a filament classification scheme and divide the filaments into several types according to their visual morphology: straight (lying on the cluster–cluster axis; 37 per cent), warped or curved (lying off the cluster–cluster axis; 33 per cent), sheets (planar configurations of galaxies; 3 per cent), uniform (1 per cent) and irregular (26 per cent). We find that straight filaments are more likely to reside between close cluster pairs and they become more curved with increasing cluster separation. This curving is toward a larger mass concentration in general. We also show that the more massive a cluster is, the more likely it is to have a larger number of filaments. Our results are found to be consistent with a Λ cold dark matter cosmology.

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Signatures in a Giant Radio Galaxy of a Cosmological Shock Wave at Intersecting Filaments of Galaxies

Cited by 32 publications

References 23 publications

Origin of galactic and extragalactic magnetic fields

Origin of galactic and extragalactic magnetic fields

A comparison of cosmological codes: properties of thermal gas and shock waves in large-scale structures

Intercluster filaments of galaxies programme: abundance and distribution of filaments in the 2dFGRS catalogue

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