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We employ the gravitational decoupling approach for static and spherically symmetric systems to develop a simple and powerful method in order to a) continuously isotropize any anisotropic solution of the Einstein field equations, and b)…

General Relativity and Quantum Cosmology · Physics 2019-10-11 R. Casadio , E. Contreras , J. Ovalle , A. Sotomayor , Z. Stuchlick

Since self-gravity is crucial in the structure formation of the universe, many hydrodynamics simulations with the effect of self-gravity have been conducted. The multigrid method is widely used as a solver for the Poisson equation of the…

Astrophysics of Galaxies · Physics 2023-10-13 Ryunosuke Maeda , Tsuyoshi Inoue , Shu-ichiro Inutsuka

In a non supervised Bayesian estimation approach for inverse problems in imaging systems, one tries to estimate jointly the unknown image pixels $f$ and the hyperparameters $\theta$ given the observed data $g$ and a model $M$ linking these…

Mathematical Physics · Physics 2009-04-28 Ali Mohammad-Djafari

Consider the Poisson equation with the Dirichlet boundary condition on a three-dimensional polyhedral domain. For singular solutions from the non-smoothness of the domain boundary, we propose new anisotropic tetrahedral mesh refinement…

Numerical Analysis · Mathematics 2016-12-21 Hengguang Li

The Inverse Problem for the estimation of a point-wise approximation error occurring at the discretization and solving of the system of partial differential equations is addressed. The set of the differences between the numerical solutions…

Numerical Analysis · Mathematics 2021-01-05 Aleksey Alekseev , Alexander Bondarev

In present paper we suggest exact solution of the Poisson problem which appears in frequently addressed applications regarding calculation of the gravitational potential of spiral galaxies. We suggest an analytical solution for the problem…

General Physics · Physics 2017-10-26 Anton A. Lipovka , Armando Meza

We propose a non grid-based interpolation scheme based on the information from the data collected from the vicinity of the query point. As a non-grid-based interpolation, the data points can be distributed randomly in a small region, and…

Numerical Analysis · Mathematics 2016-09-21 Kai Lin , Wei-Liang Qian

The Fast Multipole Method (FMM) for the Poisson equation is extended to the case of non-axisymmetric problems in an axisymmetric domain, described by cylindrical coordinates. The method is based on a Fourier decomposition of the source into…

Numerical Analysis · Mathematics 2023-01-04 Michael J. Carley

Green's function plays a significant role in both theoretical analysis and numerical computing of partial differential equations (PDEs). However, in most cases, Green's function is difficult to compute. The troubles arise in the following…

Machine Learning · Computer Science 2022-04-29 Guochang Lin , Fukai Chen , Pipi Hu , Xiang Chen , Junqing Chen , Jun Wang , Zuoqiang Shi

Adjoint field methods are both elegant and efficient for calculating sensitivity information required across a wide range of physics-based inverse problems. Here we provide a unified approach to the derivation of such methods for problems…

Geophysics · Physics 2011-09-20 Alireza Aghasi , Eric L. Miller

We propose an approach to infer large-scale heterogeneities within a small celestial body from measurements of its gravitational potential, provided for instance by spacecraft radio-tracking. The non-uniqueness of the gravity inversion is…

Earth and Planetary Astrophysics · Physics 2023-11-10 Alfonso Caldiero , Sébastien Le Maistre

Partial differential equations with distributional sources---in particular, involving (derivatives of) delta distributions---have become increasingly ubiquitous in numerous areas of physics and applied mathematics. It is often of…

Computational Physics · Physics 2019-11-22 Marius Oltean , Carlos F. Sopuerta , Alessandro D. A. M. Spallicci

The aim of this work is to formulate two new solutions by decoupling the field equations via a minimal geometric deformation in the context of self-interacting Brans-Dicke gravity. We introduce an extra source in the anisotropic fluid…

General Relativity and Quantum Cosmology · Physics 2022-01-14 M. Sharif , Amal Majid

The solution of the Poisson equation is a ubiquitous problem in computational astrophysics. Most notably, the treatment of self-gravitating flows involves the Poisson equation for the gravitational field. In hydrodynamics codes using…

Instrumentation and Methods for Astrophysics · Physics 2019-01-16 Bernhard Müller , Conrad Chan

We present an efficient numerical method, inspired by transformation optics, for solving the Poisson equation in complex and arbitrarily shaped geometries. The approach operates by mapping the physical domain to a uniform computational…

Numerical Analysis · Mathematics 2026-02-03 Deepak Gautam , Bhooshan Paradkar

A classical problem in acoustic (and electromagnetic) scattering concerns the evaluation of the Green's function for the Helmholtz equation subject to impedance boundary conditions on a half-space. The two principal approaches used for…

Numerical Analysis · Mathematics 2012-11-28 Michael O'Neil , Leslie Greengard , Andras Pataki

We describe a simple and effective algorithm for solving Poisson's equation in the context of self-gravity within the DISPATCH astrophysical fluid framework. The algorithm leverages the fact that DISPATCH stores multiple time slices and…

Instrumentation and Methods for Astrophysics · Physics 2018-06-27 J. P. Ramsey , T. Haugbølle , Å. Nordlund

We present a novel Bayesian framework for inverse problems in which the pos terior distribution is interpreted as the intensity measure of a Poisson point process (PPP). The posterior density is approximated using kernel density estimation,…

Numerical Analysis · Mathematics 2025-10-08 Zhiliang Deng , Zhiyuan Wang , Xiaomei Yang , Xiaofei Guan

This paper constructs the multipole expansion (in general relativity) of the gravitational field generated by a slowly-moving isolated source. We introduce some definitions for the source multipole moments, valid to all orders in a…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Luc Blanchet

We present a many-body $GW$ formalism for quantum subsystems embedded in discrete polarizable environments containing up to several hundred thousand atoms described at a fully ab initio random phase approximation level. Our approach is…

Chemical Physics · Physics 2024-01-26 David Amblard , Xavier Blase , Ivan Duchemin