Fejezetek a kockázat témaköréből a közgazdaságtanban

Regős, Gábor

doi:10.14267/phd.2015041

Cited by 3 publications

(4 citation statements)

References 14 publications

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“…Thus, provided we can determine the location of the caustics, we can still estimate β through the measurement of δ g for a rich galaxy cluster (Regös & Geller 1989). Recently, Regös (1996) suggested the application of gravitational lensing (e.g. Tyson, Valdes, & Wenk 1990;Kaiser & Squires 1993;Kaiser, Squires, & Broadhurst 1995;Bonnet & Mellier 1995) to determine the mass overdensity δ and therefore the unbiased value of Ω 0 .…”

Section: Introductionmentioning

confidence: 99%

Infall Regions of Galaxy Clusters

Diaferio

Geller

1997

ApJ

286

379

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In hierarchical clustering, galaxy clusters accrete mass through the aggregation of smaller systems. Thus, the velocity Ðeld of the infall regions of clusters contains signiÐcant random motion superposed on radial infall. Because the purely spherical infall model does not predict the amplitude of the velocity Ðeld correctly, methods estimating the cosmological density parameter based on this model yield unreli-) 0 able biased results. In fact, the amplitude of the velocity Ðeld depends on local dynamics and only very weakly on the global properties of the universe.We use N-body simulations of Ñat and open universes to show that the amplitude of the velocity Ðeld of the infall regions of dark matter halos is a direct measure of the escape velocity within these regions. We can use this amplitude to estimate the mass of dark matter halos within a few megaparsecs from the halo center. In this region dynamical equilibrium assumptions do not hold. The method yields a mass estimate with better than 30% accuracy. If galaxies trace the velocity Ðeld of the infall regions of clusters reliably, this method provides a straightforward way to estimate the amount of mass surrounding rich galaxy clusters from redshift data alone.

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Section: Introductionmentioning

confidence: 99%

Infall Regions of Galaxy Clusters

Diaferio

Geller

1997

ApJ

286

379

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“…The large shear between adjacent disk annuli suggests that disks might be unstable to turbulent motions, which has led to many turbulent viscosity mechanisms. Convective eddies, gravitational instabilities, internal shocks, magnetic stresses, sound waves, spiral density waves, and tidal forces have all been popular turbulence mechanisms in the past three decades (see, for example, [120], [161], [25], [112], [176], [7], [60], [172], [168], [24], [177], [157], [144], [5]).…”

Section: Turbulent Viscosity and Disk Timescalesmentioning

confidence: 99%

Accretion Disks and Eruptive Phenomena

Kenyon

1999

The Origin of Stars and Planetary Systems

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“…However, the capacity of caustic edges themselves to constrain cosmological parameters has not been pursued since the work of Ref. [8].…”

Section: Introductionmentioning

confidence: 99%

“…Following Refs. [2,3,8] but also deviating significantly from their approach, Ref. [9] demonstrated the necessity to include a cosmological term to describe the escape velocity profile of galaxy clusters as inferred from their projected phase spaces.…”

Section: Introductionmentioning

confidence: 99%

Cosmology with galaxy cluster phase spaces

2017

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We present a novel approach to constrain accelerating cosmologies with galaxy cluster phase spaces. With the Fisher matrix formalism we forecast constraints on the cosmological parameters that describe the cosmological expansion history. We find that our probe has the potential of providing constraints comparable to, or even stronger than, those from other cosmological probes. More specifically, with 1000 (100) clusters uniformly distributed in the redshift range 0 ≤ z ≤ 0.8, after applying a conservative 80% mass scatter prior on each cluster and marginalizing over all other parameters, we forecast 1σ constraints on the dark energy equation of state w and matter density parameter ΩM of σw = 0.138(0.431) and σΩ M = 0.007(0.025) in a flat universe. Assuming 40% mass scatter and adding a prior on the Hubble constant we can achieve a constraint on the CPL parametrization of the dark energy equation of state parameters w0 and wa with 100 clusters in the same redshift range: σw 0 = 0.191 and σw a = 2.712. Dropping the assumption of flatness and assuming w = −1 we also attain competitive constraints on the matter and dark energy density parameters: σΩ M = 0.101 and σΩ Λ = 0.197 for 100 clusters uniformly distributed in the range 0 ≤ z ≤ 0.8 after applying a prior on the Hubble constant. We also discuss various observational strategies for tightening constraints in both the near and far future.

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Fejezetek a kockázat témaköréből a közgazdaságtanban

Cited by 3 publications

References 14 publications

Infall Regions of Galaxy Clusters

Infall Regions of Galaxy Clusters

Accretion Disks and Eruptive Phenomena

Cosmology with galaxy cluster phase spaces

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