ORCID Profile
0000-0001-5233-8087
Current Organisation
Universität Hamburg
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Publisher: EDP Sciences
Date: 03-2010
Publisher: IOP Publishing
Date: 08-02-2013
Publisher: IOP Publishing
Date: 12-2008
Publisher: IOP Publishing
Date: 24-02-2015
Publisher: Cambridge University Press (CUP)
Date: 19-12-2011
DOI: 10.1017/JFM.2011.503
Abstract: We present a systematic study of the influence of different forcing types on the statistical properties of supersonic, isothermal turbulence in both the Lagrangian and Eulerian frameworks. We analyse a series of high-resolution, hydrodynamical grid simulations with Lagrangian tracer particles and examine the effects of solenoidal ( ergence-free) and compressive (curl-free) forcing on structure functions, their scaling exponents, and the probability density functions of the gas density and velocity increments. Compressively driven simulations show significantly larger density contrast, more intermittent behaviour, and larger fractal dimension of the most dissipative structures at the same root mean square Mach number. We show that the absolute values of Lagrangian and Eulerian structure functions of all orders in the integral range are only a function of the root mean square Mach number, but independent of the forcing. With the assumption of a Gaussian distribution for the probability density function of the velocity increments for large scales, we derive a model that describes this behaviour.
Publisher: American Physical Society (APS)
Date: 07-11-2008
Publisher: Wiley
Date: 07-2013
Publisher: EDP Sciences
Date: 20-11-2008
Publisher: American Astronomical Society
Date: 04-2022
Abstract: Primordial magnetic fields (PMFs) could explain the large-scale magnetic fields present in the universe. Inflation and phase transitions in the early universe could give rise to such fields with unique characteristics. We investigate the magnetohydrodynamic evolution of these magnetogenesis scenarios with cosmological simulations. We evolve inflation-generated magnetic fields either as (i) uniform (homogeneous) or as (ii) scale-invariant stochastic fields, and phase-transition-generated ones either as (iii) helical or as (iv) nonhelical fields from the radiation-dominated epoch. We find that the final distribution of magnetic fields in the simulated cosmic web shows a dependence on the initial strength and the topology of the seed field. Thus, the observed field configuration retains information on the initial conditions at the moment of the field generation. If detected, PMF observations would open a new window for indirect probes of the early universe. The differences between the competing models are revealed on the scale of galaxy clusters, bridges, as well as filaments and voids. The distinctive spectral evolution of different seed fields produces imprints on the correlation length today. We discuss how the differences between rotation measures from highly ionized regions can potentially be probed with forthcoming surveys.
Publisher: EDP Sciences
Date: 10-03-2011
Publisher: American Astronomical Society
Date: 10-02-2009
Publisher: American Astronomical Society
Date: 21-10-2008
DOI: 10.1086/595280
Publisher: EDP Sciences
Date: 10-2009
Publisher: EDP Sciences
Date: 10-2019
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Wolfram Schmidt.