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In this paper, we consider the 1D wave equation where the spatial domain is a bounded interval. Assuming the initial conditions to be known, we are here interested in identifying an unknown source term, while we take the Neumann derivative…

Optimization and Control · Mathematics 2011-06-30 Marianne Chapouly , Mazyar Mirrahimi

We study the local existence of strong solutions for the cubic nonlinear wave equation with data in $H^s(M)$, $s<1/2$, where $M$ is a three dimensional compact riemannian manifold. This problem is supercritical and can be shown to be…

Analysis of PDEs · Mathematics 2009-11-13 N. Burq , N. Tzvetkov

Numerical results, based on a lattice method for computational general relativity, will be presented for Cauchy evolution of initial data for the Brill, Teukolsky and polarised Gowdy space-times. The simple objective of this paper is to…

General Relativity and Quantum Cosmology · Physics 2017-08-02 Leo Brewin

We deal with the Cauchy problem for a perturbed wave equation in the half-plane with data given on a part of the space-time boundary. The equation in consideration describes a wave process in a laterally inhomogeneous medium. We propose a…

Analysis of PDEs · Mathematics 2019-11-01 M. N. Demchenko

The standard model of cosmology with nearly Gaussian, isotropic, scale invariant and adiabatic initial conditions describes the cosmological observations well. However, the study of any deviation from the mentioned conditions will open up a…

Cosmology and Nongalactic Astrophysics · Physics 2018-01-31 Mohammad Ansari Fard , Shant Baghram

We consider the Cauchy problem on nonlinear scalar conservation laws with a diffusion-type source term related to an index $s\in \R$ over the whole space $\R^n$ for any spatial dimension $n\geq 1$. Here, the diffusion-type source term…

Analysis of PDEs · Mathematics 2011-04-08 Renjun Duan , Lizhi Ruan , Changjiang Zhu

This article is devoted to the Cauchy problem for the 2D gravity-capillary water waves in fluid domains with general bottoms. We prove that the Cauchy problem in Sobolev spaces is uniquely solvable for data $\frac{1}{4}$ derivatives less…

Analysis of PDEs · Mathematics 2016-02-04 Quang-Huy Nguyen

Within the closed universe, we obtain the amplitude and frequency of gravitational waves in the terms of discrete wave numbers, wave propagation time, and cosmological constant using the deviation equation in the first-order perturbed…

General Relativity and Quantum Cosmology · Physics 2021-05-27 Jafar Khodagholizadeh , Amir H. Abbassi , Ali Vahedi , Komeil Babaei

Posterior distributions on parameters computed from experimental data using Bayesian techniques are only as accurate as the models used to construct them. In many applications these models are incomplete, which both reduces the prospects of…

General Relativity and Quantum Cosmology · Physics 2015-06-23 Christopher J. Moore , Jonathan R. Gair

We consider an one-dimensional inhomogeneous harmonic chain consisting of two different semi-infinite chains of harmonic oscillators. We study the Cauchy problem with random initial data. Under some restrictions on the interaction between…

Mathematical Physics · Physics 2021-02-09 T. V. Dudnikova

The growing field of large-scale time domain astronomy requires methods for probabilistic data analysis that are computationally tractable, even with large datasets. Gaussian Processes are a popular class of models used for this purpose…

Instrumentation and Methods for Astrophysics · Physics 2017-11-15 Daniel Foreman-Mackey , Eric Agol , Sivaram Ambikasaran , Ruth Angus

We present a numerically cheap approximation to super-sample covariance (SSC) of large scale structure cosmological probes, first in the case of angular power spectra. It necessitates no new elements besides those used for the prediction of…

Cosmology and Nongalactic Astrophysics · Physics 2019-04-17 Fabien Lacasa , Julien Grain

The spherical modes of gravitational waves (GWs) have become a major focus of recent detection campaigns due to the additional information they can provide about different properties of the source. However, GW detection is restricted to…

General Relativity and Quantum Cosmology · Physics 2023-12-07 Alejandro Torres-Orjuela

We prove global completeness in the expanding direction of spacetimes satisfying the vacuum Einstein equations on a manifold of the form $\Sigma \times S^{1}\times R$ where $\Sigma $ is a compact surface of genus $G>1.$ The Cauchy data are…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Yvonne Choquet-Bruhat , Vincent Moncrief

We prove quasi-invariance of Gaussian measures supported on Sobolev spaces under the dynamics of the three-dimensional defocusing cubic nonlinear wave equation. As in the previous work on the two-dimensional case, we employ a simultaneous…

Probability · Mathematics 2022-07-20 Trishen S. Gunaratnam , Tadahiro Oh , Nikolay Tzvetkov , Hendrik Weber

This paper investigates wave-equations on spacetimes with a metric which is locally analytic in the time. We use recent results in the theory of the non-characteristic Cauchy problem to show that a solution to a wave-equation vanishing in…

Mathematical Physics · Physics 2007-05-23 Alexander Strohmaier

This paper is devoted to a study of observability estimate for the wave equation with variable coefficients $(h^{jk}(x))_{n\times n}$ ($n\in\mathbb{N})$. We consider both the observation point lies outside the domain and the observation…

Analysis of PDEs · Mathematics 2021-12-20 Zhonghua Liao , Xiaoyu Fu

Using Fermat's principle, we analyze the effects of very long wavelength gravitational waves upon the images of a gravitationally lensed quasar. We show that the lens equation in the presence of gravity waves is equivalent to that of a lens…

Astrophysics · Physics 2011-09-09 J. Frieman , D. Harari , G. Surpi

This paper studies the Cauchy problem for systems of semi-linear wave equations on $\mathbb{R}^{3+1}$ with nonlinear terms satisfying the null conditions. We construct future global-in-time classical solutions with arbitrarily large initial…

Analysis of PDEs · Mathematics 2015-12-31 Shuang Miao , Long Pei , Pin Yu

The 1D Cauchy problem for the Dirac-Klein-Gordon system is shown to be locally well-posed for low regularity Dirac data in $\hat{H^{s,p}}$ and wave data in $\hat{H^{r,p}} \times \hat{H^{r-1,p}}$ for $1<p\le 2$ under certain assumptions on…

Analysis of PDEs · Mathematics 2007-05-23 Hartmut Pecher