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We develop a theoretical framework to study slowly rotating compact stars in a rather general class of alternative theories of gravity, with the ultimate goal of investigating constraints on alternative theories from electromagnetic and…

General Relativity and Quantum Cosmology · Physics 2015-05-30 Paolo Pani , Emanuele Berti , Vitor Cardoso , Jocelyn Read

So far, numerical simulations of ultra-faint dwarf galaxies (UFDs) failed to properly reproduce the observed size-luminosity relation. In particular, no hydro-dynamical-run managed to form UFDs with a half light radius as small as 30 pc as…

Astrophysics of Galaxies · Physics 2023-10-02 Yves Revaz

Geometric modeling by constraints leads to large systems of algebraic equations. This paper studies bipartite graphs underlaid by systems of equations. It shows how these graphs make possible to polynomially decompose these systems into…

Discrete Mathematics · Computer Science 2014-05-26 Samy Ait-Aoudia , Roland Jegou , Dominique Michelucci

We report application of a method for extracting gravitational waves to three-dimensional numerical simulation on coalescing binary neutron stars. We found the extracted wave form includes the componets corresponding to the quadrupole part…

Astrophysics · Physics 2009-11-10 Mari Kawamura , Ken-ichi Oohara

Anisotropic stresses are ubiquitous in nature, but their modeling in General Relativity is poorly understood and frame dependent. We introduce the first study on the dynamical properties of anisotropic self-gravitating fluids in a covariant…

General Relativity and Quantum Cosmology · Physics 2019-06-05 Guilherme Raposo , Paolo Pani , Miguel Bezares , Carlos Palenzuela , Vitor Cardoso

The stable critical points and their corresponding cosmology are derived in the teleparallel gravity with an added Gauss-Bonnet topological invariant term. We have analyzed the dynamics of the Universe by presenting two cosmological viable…

General Relativity and Quantum Cosmology · Physics 2023-12-12 S. A. Kadam , Santosh V Lohakare , B. Mishra

The current generation of millimeter interferometers have revealed a population of compact (r <~ 0.1 pc), massive (M ~ 100 Msun) gas cores that are the likely progenitors of massive stars. I review models for the evolution of these objects…

Astrophysics · Physics 2007-05-23 Mark R. Krumholz

The theory of contractions of multivectors, and star duality, was reorganized in a previous article, and here we present some applications. First, we study inner and outer spaces associated to a general multivector $M$ via the equations $v…

General Mathematics · Mathematics 2024-10-30 André L. G. Mandolesi

A framework to systematically decouple high order elliptic equations into combination of Poisson-type and Stokes-type equations is developed. The key is to systematically construct the underling commutative diagrams involving the complexes…

Numerical Analysis · Mathematics 2018-07-03 Long Chen , Xuehai Huang

In this work we investigate the properties of neutron stars admixed with selfinteracting scalar bosonic dark matter. The dark matter interaction is described by a generalized $\phi^n$ power-law potential. We perform a stability analysis of…

High Energy Astrophysical Phenomena · Physics 2024-12-11 Sarah Louisa Pitz , Jürgen Schaffner-Bielich

We present a method of constructing perturbative equations of motion for the geometric background of any given tensorial field theory. Requiring invariance of the gravitational dynamics under spacetime diffeomorphisms leads to a PDE system…

General Relativity and Quantum Cosmology · Physics 2019-09-04 Tobias Reinhart , Nils Alex

A ccc-generically supercompact cardinal $\kappa$ can be smaller than or equal to the continuum. On the other hand, such a cardinal $\kappa$ still satisfies diverse largeness properties, like that it is a stationary limit of ccc-generically…

Logic · Mathematics 2022-02-17 Sakaé Fuchino , Hiroshi Sakai

We are developing 3 dimensional simulation codes for coalescing binary neutron stars. A code using the maximal slicing condition is obtained. To evaluate the gravitational radiation, we implemented a gauge-invariant wave extraction and…

Astrophysics · Physics 2007-05-23 Mari Kawamura , Ken-ichi Oohara , Takashi Nakamura

We model gravitational collapse leading to star formation in a wide range of isolated disk galaxies using a three-dimensional, smoothed particle hydrodynamics code. The model galaxies include a dark matter halo and a disk of stars and…

Astrophysics · Physics 2009-11-10 Yuexing Li , Mordecai-Mark Mac Low , Ralf S. Klessen

In the present article, we have constructed a static charged anisotropic compact star model of Einstein field equations for a spherically symmetric space-time geometry. Specifically, we have extended the charged isotropic Heintzmann…

General Relativity and Quantum Cosmology · Physics 2018-08-29 E. Morales , Francisco Tello-Ortiz

We introduce a novel method for discerning optical telescope images of stars from those of galaxies using Gaussian processes (GPs). Although applications of GPs often struggle in high-dimensional data modalities such as optical image…

Instrumentation and Methods for Astrophysics · Physics 2022-03-14 Amanda L. Muyskens , Imène R. Goumiri , Benjamin W. Priest , Michael D. Schneider , Robert E. Armstrong , Jason M. Bernstein , Ryan Dana

We describe a mechanism for using discrete symmetries to solve the doublet-triplet splitting problem of four-dimensional supersymmetric GUT's. We present two versions of the mechanism, one via ``deconstruction,'' and one in terms of…

High Energy Physics - Phenomenology · Physics 2007-05-23 Edward Witten

Motivation: Motivated by the growing interest in understanding the role of non-metricity in describing dense stellar systems, in this paper, we study compact stellar configurations within the framework of linear $f(Q)$ gravity. Methodology:…

General Relativity and Quantum Cosmology · Physics 2026-04-28 Arpita Ghosh , Abhishek Paul , Ranjan Sharma , Samstuti Chanda

The exact analytical solutions for vacuum electromagnetic fields of slowly rotating magnetized compact stars in conformal gravity have been studied. Taking the realistic dipolar magnetic field configuration for the star, analytical…

General Relativity and Quantum Cosmology · Physics 2018-06-11 Bobur Turimov , Bobomurat Ahmedov , Ahmadjon Abdujabbarov , Cosimo Bambi

We present a spectral decomposition technique and its applications to a sample of galaxies hosting large-scale counter-rotating stellar disks. Our spectral decomposition technique allows to separate and measure the kinematics and the…

Astrophysics of Galaxies · Physics 2014-02-24 L. Coccato , L. Morelli , A. Pizzella , E. M. Corsini , E. Dalla Bonta' , L. M. Buson