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We consider turbulent synchrotron emitting media that also exhibits Faraday rotation and provide a statistical description of synchrotron polarization fluctuations. In particular, we consider these fluctuations as a function of the spatial…

Astrophysics of Galaxies · Physics 2016-03-09 Alex Lazarian , Dmitri Pogosyan

This paper concerns the reconstruction of the scattering coefficient in a two-dimensional transport equation from angularly averaged measurements when the probing source is isotropic and time-harmonic. This is a practical setting in the…

Analysis of PDEs · Mathematics 2011-10-17 Guillaume Bal , Francois Monard

We examine the time-dependent behavior of a nonlinear system driven by a two-frequency forcing. By using a non-perturbative approach, we are able to derive an asymptotic expression, valid in the long-time limit, for the time average of the…

Statistical Mechanics · Physics 2015-02-17 Jesús Casado-Pascual , David Cubero , Ferruccio Renzoni

Here we present a Bayesian method of including discrete measurements of dispersion measure due to the interstellar medium in the direction of a pulsar as prior information in the analysis of that pulsar. We use a simple simulation to show…

Instrumentation and Methods for Astrophysics · Physics 2013-12-10 Lindley Lentati , Paul Alexander , Michael P. Hobson

Classically, anisotropic surface wave tomography is treated as an optimisation problem where it proceeds through a linearised two-step approach. It involves the construction of 2D group or phase velocity maps for each considered period,…

Geophysics · Physics 2020-12-08 John Keith Magali

The near-infrared background between 0.5 $\mu$m to 2 $\mu$m contains a wealth of information related to radiative processes in the universe. Infrared background anisotropies encode the redshift-weighted total emission over cosmic history,…

Cosmology and Nongalactic Astrophysics · Physics 2019-04-24 Chang Feng , Asantha Cooray , Jamie Bock , Tzu-Ching Chang , Olivier Doré , Mario G. Santos , Marta B. Silva , Michael Zemcov

We study the volatility functional inference by Fourier transforms. This spectral framework is advantageous in that it harnesses the power of harmonic analysis to handle missing data and asynchronous observations without any artificial time…

Statistics Theory · Mathematics 2019-11-07 Richard Y. Chen

The complex scaling/perfectly matched layer method is a widely spread technique to simulate wave propagation problems in open domains. The method is very popular, because its implementation is very easy and does not require the knowledge of…

Numerical Analysis · Mathematics 2021-06-29 Martin Halla

A joint action of depth and bandwidth depolarization in the interstellar medium is considered using a model of N homogeneous synchrotron layers with Faraday rotation. The bandwidth depolarization can be used in multifrequency polarimetric…

Astrophysics · Physics 2007-05-23 E. N. Vinyajkin

Starting with far field data of time-harmonic acoustic or electromagnetic waves radiated by a collection of compactly supported sources in two-dimensional free space, we develop criteria and algorithms for the recovery of the far field…

Analysis of PDEs · Mathematics 2016-07-20 Roland Griesmaier , John Sylvester

The X-ray signal from active galactic nuclei and black hole X-ray binaries is highly variable on a range of timescales. This variability can be exploited to map the region of interest close to the black hole, which is far too small to…

High Energy Astrophysical Phenomena · Physics 2023-05-24 Adam Ingram

We propose a reliable direct imaging method based on the reverse time migration for finding extended obstacles with phaseless total field data. We prove that the imaging resolution of the method is essentially the same as the imaging…

Numerical Analysis · Mathematics 2015-02-04 Zhiming Chen , Guanghui Huang

Under nonuniform convection, the distribution of diffusive particles can exhibit dipole and quadrupole anisotropy induced by the fluid inertial and shear force, respectively. These convection-related anisotropies, unlike the Compton-Getting…

High Energy Astrophysical Phenomena · Physics 2022-10-26 Yiran Zhang , Siming Liu , Dejin Wu

We study the possibility of using quadrupole moments of auto-convolved galaxy images to measure cosmic shear. The autoconvolution of an image corresponds to the inverse Fourier transformation of its power spectrum. The new method has the…

Cosmology and Nongalactic Astrophysics · Physics 2016-10-26 Xiangchong Li , Jun Zhang

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…

Solar and Stellar Astrophysics · Physics 2015-06-16 S. Hekker , Y. Elsworth , S. Basu , A. Mazumdar , V. Silva Aguirre , W. J. Chaplin

Diffraction limit is manifested in the loss of high spatial frequency information that results from decay of evanescent waves. As a result, conventional far-field optics yields no information about an object's subwavelength features. Here…

Optics · Physics 2012-01-24 Leonid Alekseyev , Evgenii Narimanov , Jacob Khurgin

Photometric light curves suffer from fundamental degeneracies that limit surface information recovery. We demonstrate that astrometry enables access to complementary information through photocentre variations induced by rotating surface…

Solar and Stellar Astrophysics · Physics 2026-04-06 Conaire Deagan , Benjamin T. Montet

We propose a method to probe the homogeneity of a general universe, without assuming symmetry. We show that isotropy can be tested at remote locations on the past lightcone by comparing the line-of-sight and transverse expansion rates,…

Cosmology and Nongalactic Astrophysics · Physics 2019-06-05 Raul Jimenez , Roy Maartens , Ali Rida Khalifeh , Robert R. Caldwell , Alan F. Heavens , Licia Verde

The development of an analytically iterative method for solving steady-state as well as unsteady-state problems of cosmic-ray (CR) modulation is proposed. Iterations for obtaining the solutions are constructed for the spherically symmetric…

Instrumentation and Methods for Astrophysics · Physics 2017-07-04 Yuriy L. Kolesnyk , Pavol Bobik , Boris A. Shakhov , Marian Putis

With the space-borne missions CoRoT and Kepler, a large amount of asteroseismic data is now available. So-called global oscillation parameters are inferred to characterize the large sets of stars, to perform ensemble asteroseismology, and…

Solar and Stellar Astrophysics · Physics 2015-06-12 B. Mosser , E. Michel , K. Belkacem , M. J. Goupil , A. Baglin , C. Barban , J. Provost , R. Samadi , M. Auvergne , C. Catala