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We analyse the evolution of cosmological perturbations which leads to the formation of large voids in the distribution of galaxies. We assume that perturbations are spherical and all components of the Universe - radiation, matter and dark…

Cosmology and Nongalactic Astrophysics · Physics 2020-08-04 Maksym Tsizh , Bohdan Novosyadlyj

We consider a system of nonlinear wave equations with constraints that arises from the Einstein equations of general relativity and describes the geometry of the so-called Gowdy symmetric spacetimes on T3. We introduce two numerical…

General Relativity and Quantum Cosmology · Physics 2009-01-08 Paulo Amorim , Christine Bernardi , Philippe G. LeFloch

In this work, we study the evolution with redshift of the colour-magnitude relation (CMR) of early-type galaxies. This evolution is analyzed through cosmological numerical simulations from z = 2 to z = 0. The preliminary results shown here…

Astrophysics of Galaxies · Physics 2020-05-12 L. J. Zenocratti , A. V. Smith Castelli , M. E. De Rossi , F. R. Faifer

A new model for evolving Evolutionary Algorithms (EAs) is proposed in this paper. The model is based on the Multi Expression Programming (MEP) technique. Each MEP chromosome encodes an evolutionary pattern that is repeatedly used for…

Neural and Evolutionary Computing · Computer Science 2021-10-13 Mihai Oltean

In this paper, we consider the initial value problem for the Einstein-Vlasov-Scalar field equations in temporal gauge, where the initial data are prescribed on two characteristic smooth intersecting hypersurfaces. From a suitable choice of…

Mathematical Physics · Physics 2016-08-04 Marcel Dossa , Jean Baptiste Patenou

Consider a generalized Oseen evolution operator in 3D exterior domains, that is generated by a non-autonomous linearized system arising from time-dependent rigid motions. This was found by Hansel and Rhandi, and then the theory was…

Analysis of PDEs · Mathematics 2025-02-19 Yosuke Asami , Toshiaki Hishida

This series of papers is intended to present astrocladistics in some detail and evaluate this methodology in reconstructing phylogenies of galaxies. Being based on the evolution of all the characters describing galaxies, it is an objective…

Astrophysics · Physics 2007-05-23 Didier Fraix-Burnet , Philippe Choler , Emmanuel J. P. Douzery , Anne Verhamme

We introduce $k$-evolution, a relativistic $N$-body code based on $\textit{gevolution}$, which includes clustering dark energy among its cosmological components. To describe dark energy, we use the effective field theory approach. In…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-23 Farbod Hassani , Julian Adamek , Martin Kunz , Filippo Vernizzi

We have computed a series of realistic and self-consistent models of the emitted spectra of H{\sc ii} galaxies. Our models combine different codes of chemical evolution, evolutionary population synthesis and photoionization. The emitted…

Astrophysics · Physics 2009-11-13 M. Martín Manjón , M. Mollá , A. I. Díaz , R. Terlevich

The aim of this article is to propose a systematic study of transparent boundary conditions for finite difference approximations of evolution equations. We try to keep the discussion at the highest level of generality in order to apply the…

Numerical Analysis · Mathematics 2016-09-23 Jean-François Coulombel

Masking the horizontal branch and giant stars allows unambiguous measurements of mean age and metallicity in simple old stellar populations from metal and hydrogen line strengths. Billion year resolution is possible in the luminous halos of…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Jeremy Mould

The space of derivations of finite dimensional evolution algebras associated to graphs over a field with characteristic zero has been completely characterized in the literature. In this work we generalize that characterization by describing…

Rings and Algebras · Mathematics 2020-06-23 Tiago Reis , Paula Cadavid

This lecture is devoted to the problem of computing initial data for the Cauchy problem of 3+1 general relativity. The main task is to solve the constraint equations. The conformal technique, introduced by Lichnerowicz and enhanced by York,…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Eric Gourgoulhon

The dynamics of gravitational waves is investigated in full 3+1 dimensional numerical relativity, emphasizing the difficulties that one might encounter in numerical evolutions, particularly those arising from non-linearities and gauge…

General Relativity and Quantum Cosmology · Physics 2011-09-09 Peter Anninos , Joan Masso , Edward Seidel , Wai-Mo Suen , Malcolm Tobias

The paper examines stochastic diffusion within an expanding space-time framework. It starts with providing a rationale for the considered model and its motivation from cosmology where the expansion of space-time is used in modelling various…

Probability · Mathematics 2023-12-22 Philip Broadbridge , Illia Donhauzer , Andriy Olenko

Numerical relativity became a powerful tool to investigate the dynamics of binary problems with black holes or neutron stars as well as the very structure of General Relativity. Although public numerical relativity codes are available to…

General Relativity and Quantum Cosmology · Physics 2015-06-16 Hirotada Okawa

We consider the Cauchy problem for a $3$-evolution operator $P$ with $(t,x)$-depending coefficients and complex valued lower order terms. We assume the initial data to be Gevrey regular and to admit an exponential decay at infinity, that…

Analysis of PDEs · Mathematics 2021-12-30 Alexandre Arias Junior , Alessia Ascanelli , Marco Cappiello

We present a new derivation of the equations governing the oscillations of slowly rotating relativistic stars. Previous investigations have been mostly carried out in the Regge-Wheeler gauge. However, in this gauge the process of…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Johannes Ruoff , Adamantios Stavridis , Kostas D. Kokkotas

In this paper, we investigate the long-time behavior of solutions to the two-dimensional Navier-Stokes equations with initial data evolving under the influence of the planar Couette flow. We focus on general perturbations, which may be…

Analysis of PDEs · Mathematics 2025-05-14 Ning Liu , Ping Zhang , Weiren Zhao

This Living Review updates a previous version which its itself an update of a review article. Numerical exploration of the properties of singularities could, in principle, yield detailed understanding of their nature in physically realistic…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Beverly K. Berger