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Radial velocity fluctuations on the plane of the sky are a powerful tool for studying the turbulent dynamics of emission line regions. We conduct a systematic statistical analysis of the H alpha velocity field for a diverse sample of 9 H II…

Astrophysics of Galaxies · Physics 2023-06-14 J. García-Vázquez , William J. Henney , H. O. Castañeda

The ionized interstellar medium disperses pulsar radio signals, resulting in a stochastic time-variable delay known as the dispersion measure (DM) noise. In the wideband paradigm of pulsar timing, we measure a DM together with a time of…

Instrumentation and Methods for Astrophysics · Physics 2025-08-27 Abhimanyu Susobhanan , Rutger van Haasteren

The cause of the extended rotation curves of galaxies is investigated. It is shown that conventional sources and most exotic sources for the needed gravitational fields are implausible. We suggest spatial fluctuations in a scalar field,…

Astrophysics · Physics 2007-05-23 H. L. Helfer

We investigate a L\'evy-Walk alternating between velocities $\pm v_0$ with opposite sign. The sojourn time probability distribution at large times is a power law lacking its mean or second moment. The first case corresponds to a ballistic…

Statistical Mechanics · Physics 2014-06-03 D. Froemberg , E. Barkai

We examine statistics of fluctuations of the laser beam intensity at its propagating in turbulent atmosphere. We are interested in relatively large propagating distances and the remote tail of the probability density function. The tail is…

Optics · Physics 2024-03-07 Igor V. Kolokolov , Vladimir V. Lebedev

Gravitational radiation that propagates through an inhomogeneous mass distribution is subject to random gravitational lensing, or scattering, causing variations in the wave amplitude and temporal smearing of the signal. A statistical theory…

Astrophysics · Physics 2009-11-10 J-P Macquart

The L\'evy, jumping process, defined in terms of the jumping size distribution and the waiting time distribution, is considered. The jumping rate depends on the process value. The fractional diffusion equation, which contains the variable…

Statistical Mechanics · Physics 2009-06-10 Tomasz Srokowski

The remarkable rapid variations in radio flux density and polarization of the quasar PKS 0405-385 observed in 1996 are subject to a correlation analysis, from which characteristic time scales and amplitudes are derived. The variations are…

Astrophysics · Physics 2009-11-07 Barney J. Rickett , Lucyna Kedziora-Chudczer , David L. Jauncey

To obtain the most accurate pulse arrival times from radio pulsars, it is necessary to correct or mitigate the effects of the propagation of radio waves through the warm and ionised interstellar medium. We examine both the strength of…

Instrumentation and Methods for Astrophysics · Physics 2016-11-15 R. M. Shannon , J. M. Cordes

We establish a connection between the scattering inverse problem and the determination of the distribution of the position of the Levy process at the exit time of a bounded interval in term of its Levy exponent.

Probability · Mathematics 2007-05-23 Sonia Fourati

We studied the turbulence spectrum of the local interstellar plasma in the direction of PSR J0437-4715, on the basis of our observations and those reported earlier by others. We combine these data to form a structure function for the…

Astrophysics · Physics 2009-11-11 T. V. Smirnova , C. R. Gwinn , V. I. Shishov

In this article, on the basis of the Langevin equation applied to velocity fluctuations, we numerically model the Partial Variance of Increments, which is a useful tool to measure time and spatial correlations in space plasmas. We consider…

Plasma Physics · Physics 2023-07-26 Iván Gallo-Méndez , Pablo S. Moya

A study on the spatial organization and velocity fluctuations of non Brownian spherical particles settling at low Reynolds number in a vertical Hele-Shaw cell is reported. The particle volume fraction ranged from 0.005 to 0.05, while the…

Fluid Dynamics · Physics 2019-08-17 A. Boschan , B. L. Ocampo , M. Annichini , G. Gauthier

Observations over the last two decades have shown that a significant fraction of all flat-spectrum, extragalactic radio sources exhibit flux density variations on timescales of a day or less at frequencies of several GHz. It has been…

Within the point vortex model, we compute the probability distribution function of the velocity fluctuations induced by same-signed vortices scattered within a disk according to a fractal distribution of distances to origin $\sim…

Statistical Mechanics · Physics 2016-05-25 Audun Skaugen , Luiza Angheluta

We investigate the impact of external periodic potentials on superdiffusive random walks known as Levy flights and show that even strongly superdiffusive transport is substantially affected by the external field. Unlike ordinary random…

Statistical Mechanics · Physics 2009-11-07 D. Brockmann , T. Geisel

We critically examine how well the evolution of large-scale density perturbations is followed in cosmological $N$-body simulations. We first run a large volume simulation and perform a mode-by-mode analysis in three-dimensional Fourier…

When a gravitational wave (GW) from a distant source propagates through the universe, its amplitude and phase change due to gravitational lensing by the inhomogeneous mass distribution. We derive the amplitude and phase fluctuations, and…

Astrophysics · Physics 2009-11-13 Ryuichi Takahashi

I use a method based on interstellar scintillations for discerning information about source sizes on scales less than one micro-arc sec. I use a comprehensive model for a pulsar signal, scintillated amplitude modulated noise, that includes…

Astrophysics · Physics 2007-05-23 J. M. Cordes

Galactic cosmic ray transport relies on the existence of turbulence on scales comparable with the gyration radius of the particles and with wavenumber vector oriented along the local magnetic field. In the standard picture, in which…

High Energy Astrophysical Phenomena · Physics 2023-12-29 O. Pezzi , P. Blasi
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