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Fluctuations due to a super-position of uncorrelated Lorentzian pulses with a random distribution of amplitudes and duration times are considered. These are demonstrated to be strongly intermittent in the limit of weak pulse overlap,…

等离子体物理 · 物理学 2018-03-14 O. E. Garcia , A. Theodorsen

Extreme scattering events (ESEs) in the interstellar medium (ISM) were first observed in regular flux measurements of compact extragalactic sources. They are characterized by a flux variation over a period of weeks, suggesting the passage…

Turbulence is a vital part of the interstellar medium (ISM) of galaxies, contributing significantly to galaxy energy budgets and acting as a regulator of star formation. Despite this, little is understood about ISM turbulence empirically.…

星系天体物理 · 物理学 2021-07-26 Dana Simard , Vikram Ravi

Weak interstellar scintillations of pulsar B0809+74 were observed at two epochs using a 30m EISCAT antenna at 933 MHz. These have been used to constrain the spectrum, the distribution and the transverse velocity of the scattering plasma…

天体物理学 · 物理学 2015-06-24 Barney Rickett , Bill Coles , Jussi Markkanen

The behavior of a newly introduced overlap parameter is analyzed, measuring the correlation between intensity fluctuations of waves in random media in different physical regimes, with varying amount of disorder and non-linearity. Its…

统计力学 · 物理学 2015-12-01 Fabrizio Antenucci , Andrea Crisanti , Luca Leuzzi

Context. The spatially coherent multipath propagation of pulsar radiation leads to a temporal and spectral interference patterns called scintillation. It is caused by density variations in the ionized interstellar medium, which often take…

高能天体物理现象 · 物理学 2026-05-15 Tim Sprenger , Xun Shi , Olaf Wucknitz , Robert A. Main

An observer, situated several thousand light-years away from a radio pulsar, finds himself embedded in the diffraction pattern resulting from the propagation of the radio waves through the irregular interstellar medium. The observer's…

广义相对论与量子宇宙学 · 物理学 2010-11-01 Redouane Fakir

Plastic scintillation detectors are increasingly used to measure dose distributions in the context of radiotherapy treatments. Their water-equivalence, real-time response and high spatial resolution distinguish them from traditional…

医学物理 · 物理学 2021-09-22 Emily Cloutier , Louis Archambault , Luc Beaulieu

Asteroseismology, i.e. the study of the internal structures of stars via their global oscillations, is a valuable tool to obtain stellar parameters such as mass, radius, surface gravity and mean density. These parameters can be obtained…

太阳与恒星天体物理 · 物理学 2015-06-16 S. Hekker , Y. Elsworth , S. Basu , A. Mazumdar , V. Silva Aguirre , W. J. Chaplin

The aim of this article is to establish asymptotic distributions and consistency of subsampling for spectral density and for magnitude of coherence for non-stationary, almost periodically correlated time series. We show the asymptotic…

统计理论 · 数学 2011-02-11 Łukasz Lenart

We analyze deterministic and random temporal variations in dispersion measure (DM) from the full three-dimensional velocities of pulsars with respect to the solar system, combined with electron-density variations on a wide range of length…

高能天体物理现象 · 物理学 2016-09-29 Michael T. Lam , James M. Cordes , Shami Chatterjee , Megan L. Jones , Maura A. McLaughlin , John W. Armstrong

We provide a theoretical description of synchrotron fluctuations arising from magnetic turbulence. We derive an expression that relates the correlation of synchrotron fluctuations for an arbitrary index of relativistic electrons with the…

星系天体物理 · 物理学 2015-05-28 Alex Lazarian , Dmitri Pogosyan

Some experimental results of correlation functions in Bose-Einstein interferometry measurements exhibit a non smooth behaviour - oscillations. Possible origin of such a behaviour in non-trivial spatial distribution of the source is…

高能物理 - 唯象学 · 物理学 2009-09-25 Peter Filip

Numerical simulation is used to analyze statistical characteristics of vortex beams propagating in the atmosphere. The cumulative distribution function and the probability density function of intensity fluctuations are compared for Gaussian…

光学 · 物理学 2019-09-04 V. P. Aksenov , V. V. Dudorov , V. V. Kolosov

We carried out observations of pulsar PSR B1919+21 at 324 MHz to study the distribution of interstellar plasma in the direction of this pulsar. We used the RadioAstron (RA) space radiotelescope together with two ground telescopes:…

太阳与恒星天体物理 · 物理学 2017-05-10 V. I. Shishov , T. V. Smirnova , C. R. Gwinn , A. S. Andrianov , M. V. Popov , A. G. Rudnitskiy , V. A. Soglasnov

Interstellar scintillation (ISS) has been established as the cause of the random variations seen at centimetre wavelengths in many compact radio sources on timescales of a day or less. Observations of ISS can be used to probe structure both…

Context: By providing information about the location of scattering material along the line of sight (LoS) to pulsars, scintillation arcs are a powerful tool for exploring the distribution of ionized material in the interstellar medium.…

Interstellar scattering causes pulsar profiles to grow asymmetrically, thus affecting the pulsar timing residuals, and is strongest at lower frequencies. Different Interstellar medium models predict different frequency ($\nu$) and…

高能天体物理现象 · 物理学 2019-05-01 Karishma Bansal , G. B. Taylor , Kevin Stovall , Jayce Dowell

We measure the effects of interstellar scattering on average pulse profiles from 13 radio pulsars with simple pulse shapes. We use data from the LOFAR High Band Antennas, at frequencies between 110 and 190~MHz. We apply a forward fitting…

A statistical model is used to determine how stochastic fluctuations in the intensities of orthogonal polarization modes contribute to the modulation and depolarization of pulsar radio emission. General expressions for the distributions of…

高能天体物理现象 · 物理学 2023-12-19 M. M. McKinnon