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200 papers

We perform numerical simulations in the close vicinity of a slowly rotating young stellar object. Using our own resistive MHD Zeus347 code in 2D axisymmetry, magnetospheric interaction experiences four robust stages in evolution.…

Solar and Stellar Astrophysics · Physics 2011-10-27 Miljenko Cemeljic , Hsien Shang

We construct barotropic stellar equilibria, containing magnetic fields with both poloidal and toroidal field components. We extend earlier results by exploring the effect of different magnetic field and current distributions. Our results…

Solar and Stellar Astrophysics · Physics 2015-06-04 S. K. Lander , D. I. Jones

We construct a class of closed timelike curves (CTCs) using a compactified extra dimension $u$. A nonzero metric element $g_{tu}(u)$ enables particles to travel backwards in global time $t$. The compactified dimension guarantees that the…

General Relativity and Quantum Cosmology · Physics 2015-06-11 Chiu Man Ho , Thomas J. Weiler

Orbits of test particles and light rays are an important tool to study the properties of space-time metrics. Here we systematically study the properties of the gravitational field of a globally regular magnetic monopole in terms of the…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Valeria Kagramanova , Jutta Kunz , Claus Laemmerzahl

We conduct 3D magneto-hydrodynamic (MHD) simulations in order to test the stability of the magnetic equilibrium configuration described by Duez & Mathis (2010). This analytically-derived configuration describes the lowest energy state for a…

Solar and Stellar Astrophysics · Physics 2015-05-20 V. Duez , J. Braithwaite , S. Mathis

Sequences based on the Distant Dipolar Field (DDF) have shown great promise for novel spectroscopy and imaging. Unless spatial variation in the longitudinal magnetization, M_{z}(s), is eliminated by relaxation, diffusion, or spoiling…

Medical Physics · Physics 2019-10-24 Curtis A. Corum , Arthur F. Gmitro

We study the linear stability of vacuum static, spherically symmetric solutions to the gravitational field equations of the Bergmann-Wagoner-Nordtvedt class of scalar-tensor theories (STT) of gravity, restricting ourselves to nonphantom…

General Relativity and Quantum Cosmology · Physics 2023-11-14 Kirill A. Bronnikov , Sergei V. Bolokhov , Milena V. Skvortsova , Kodir Badalov , Rustam Ibadov

The magnetic field in stellar radiation zones can play an important role in phenomena such as mixing, angular momentum transport, etc. We study the effect of rotation on the stability of a predominantly toroidal magnetic field in the…

Solar and Stellar Astrophysics · Physics 2015-06-15 Alfio Bonanno , Vadim Urpin

The present study aims at studying the flow and field produced by a stellar radiative zone which is initially made to rotate differentially in the presence of a large-scale poloidal magnetic field threading the whole domain. We focus both…

Solar and Stellar Astrophysics · Physics 2020-09-02 L. Jouve , F. Lignières , M. Gaurat

In this work we consider the evolution of a massive scalar field in cylindrically symmetric space-times. Quasinormal modes have been calculated for static and rotating cosmic cylinders. We found unstable modes in some cases. Rotating as…

General Relativity and Quantum Cosmology · Physics 2010-04-06 Alan B. Pavan , E. Abdalla , C. Molina

We study linear perturbations around time dependent spherically symmetric solutions in the Lambda_3 massive gravity theory, which self-accelerate in the vacuum. We find that the dynamics of the scalar perturbations depend on the coordinate…

High Energy Physics - Theory · Physics 2015-06-16 Nima Khosravi , Gustavo Niz , Kazuya Koyama , Gianmassimo Tasinato

Magnetohydrodynamic (MHD) instabilities can play an important role in the structure and dynamics of the pulsar magnetosphere. We consider the instabilitycaused by differential rotation that is suggested by many theoretical models. Stability…

High Energy Astrophysical Phenomena · Physics 2015-06-04 V. Urpin

Dynamical issues associated with quantum fields in Rindler space are addressed in a study of the interaction between two sources at rest generated by the exchange of scalar particles, photons and gravitons. These static interaction energies…

High Energy Physics - Theory · Physics 2011-05-10 F. Lenz , K. Ohta , K. Yazaki

Well controlled and highly stable magnetic fields are desired for a wide range of applications in physical research, including quantum metrology, sensing, information processing, and simulation. Here we introduce a low-cost hybrid assembly…

Quantum Physics · Physics 2018-12-21 Frederick Hakelberg , Philip Kiefer , Matthias Wittemer , Tobias Schaetz , Ulrich Warring

Extremely long-lived, time-dependent, spatially-bound scalar field configurations are shown to exist in $d$ spatial dimensions for a wide class of polynomial interactions parameterized as $V(\phi) = \sum_{n=1}^h\frac{g_n}{n!}\phi^n$.…

High Energy Physics - Theory · Physics 2009-11-10 Marcelo Gleiser

The physical origin of spacetime discreteness remains a central open problem in quantum gravity, with most existing approaches relying on specific microscopic structures or model-dependent assumptions. In this letter, spacetime discreteness…

General Relativity and Quantum Cosmology · Physics 2026-05-26 Weihu Ma , Yu-Gang Ma

The stability of matter composed of electrons and static nuclei is investigated for a relativistic dynamics for the electrons given by a suitably projected Dirac operator and with Coulomb interactions. In addition there is an arbitrary…

Statistical Mechanics · Physics 2009-10-28 Elliott H. Lieb , Heinz Siedentop , Jan Philip Solovej

In the absence of an active dynamo, purely poloidal magnetic field configurations are unstable to large-scale dynamical perturbations, and decay via reconnection on an Alfvenic timescale. Nevertheless, a number of classes of dynamo-free…

Astrophysics · Physics 2009-11-13 Avery E. Broderick , Ramesh Narayan

We derive a necessary condition for the existence of marginally stable circular orbits of test particles in stationary axisymmetric spacetimes which possess a refection symmetry with respect to the equatorial plane; photon orbits are also…

General Relativity and Quantum Cosmology · Physics 2016-08-08 Shabnam Beheshti , Edgar Gasperin

Neutron stars can harbor extremely strong magnetic fields, yet the structure and stability of their magnetic field configuration remain poorly understood. Observations of pulsars indicate that the large-scale external field is predominantly…

High Energy Astrophysical Phenomena · Physics 2026-05-25 Aurora Capobianco , William Cook , Sebastiano Bernuzzi , Brynmor Haskell , Jacob Fields