A5077121632- Black Holes and Theoretical Physics
- Cosmology and Gravitation Theories
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Galaxies: Formation, Evolution, Phenomena
- Meteorological Phenomena and Simulations
- Parallel Computing and Optimization Techniques
- Scientific Computing and Data Management
- Advanced Mathematical Physics Problems
- Mechanics and Biomechanics Studies
- Noncommutative and Quantum Gravity Theories
- Aquatic and Environmental Studies
- Gamma-ray bursts and supernovae
- Model Reduction and Neural Networks
- Particle physics theoretical and experimental studies
- Distributed and Parallel Computing Systems
- Computational Physics and Python Applications
- Context-Aware Activity Recognition Systems
- Adaptive optics and wavefront sensing
- IoT and Edge/Fog Computing
- Marine and environmental studies
- Particle Accelerators and Free-Electron Lasers
- Nonlinear Waves and Solitons
- Radiative Heat Transfer Studies
- Numerical methods in inverse problems
Sci-Tech Daresbury
2022
Daresbury Laboratory
2019-2021
Istituto Nazionale di Fisica Nucleare, Sezione di Catania
2016-2018
University of Catania
2004-2017
Max Planck Institute for Gravitational Physics
2011-2015
Max Planck Society
2012-2015
Louisiana State University
2001-2012
Pennsylvania State University
2006-2008
We describe the Einstein Toolkit, a community-driven, freely accessible computational infrastructure intended for use in numerical relativity, relativistic astrophysics, and other applications. The toolkit, developed by collaboration involving researchers from multiple institutions around world, combines core set of components needed to simulate astrophysical objects such as black holes, compact objects, collapsing stars, well full suite analysis tools. Toolkit is currently based on Cactus...
A model for a flat isotropic universe with negative cosmological constant $\ensuremath{\Lambda}$ and massless scalar field as sole matter content is studied within the framework of loop quantum cosmology. By application methods introduced $\ensuremath{\Lambda}=0$, physical Hilbert space set Dirac observables are constructed. As in that case, plays here role an emergent time. The properties system found to be similar those $k=1$ Friedmann-Robertson-Walker (FRW) model: small energy densities,...
We construct a three-dimensional, fully relativistic numerical model of universe filled with an inhomogeneous pressureless fluid, starting from initial data that represent perturbation the Einstein–de Sitter model. then measure departure average expansion rate respect to this homogeneous and isotropic reference model, comparing local quantities predictions linear theory. find collapsing perturbations reach turnaround point much earlier than expected spherical top-hat collapse deviation one...
We use high-redshift type Ia supernova and compact radio source data in order to test the infrared (IR) fixed point model of late Universe which was proposed recently. It describes a cosmology with time dependent cosmological constant Newton whose dynamics arises from an underlying renormalization group flow near IR-attractive point. Without any fine-tuning or quintessence field it yields ΩM = ΩΛ 1/2. Its characteristic t4/3-dependence scale factor leads distance–redshift relation...
The idea of black-hole lattices as models for the large-scale structure universe has been under scrutiny several decades, and some properties these systems have elucidated recently in context problem cosmological backreaction. complete, three-dimensional fully relativistic evolution system has, however, never tackled. We explicitly construct first solutions by numerically integrating Einstein's equation case an eight-black-hole lattice with topology S3.
We present the numerical evolution of a family conformally-flat, infinite, expanding cubic black-hole lattices. solve for initial data using an initial-data prescription presented recently, along with new multigrid solver developed this purpose. then apply standard tools relativity to calculate time development dataset and derive quantities cosmological relevance, such as scaling proper lengths. Similarly case S3 lattices, we find that length remains close analytical solution...
The apparent properties of distant objects encode information about the way light they emit propagates to an observer, and therefore curvature underlying spacetime. Measuring relationship between redshift $z$ luminosity distance $D_{\rm L}$ a standard candle, for example, yields on Universe's matter content. In practice, however, in order decode this observer needs make assumption functional form L}(z)$ relation; other words, cosmological model be assumed. work, we use numerical-relativity...
AI-based weather emulators have begun to rival the accuracy of traditional numerical solvers, for a fraction computational cost. The question whether they can be reliably deployed in all use cases (e.g., forecast extreme scenarios), however, is still open. We outline an ensembling strategy based on architectural variations Prithvi WxC foundation model (FM), highlighting impact each these physical and ability capture distributional extremes. A simple ensemble 100 models sufficient observe...
The search for solutions of Einstein's equations representing relativistic cosmological models with a discrete matter content has been remarkably fruitful in the last decade. In this review we discuss progress made study specific subclass cosmologies, black-hole lattice models. particular, illustrate techniques used construction these spacetimes, and examine their resulting physical properties. This includes large-scale dynamics, dressing mass due to interaction between individual black...
We discuss the possibility of a dimensional reduction Einstein equations in S3 black-hole lattices. It was reported previous literature that evolution spaces containing curves local, discrete rotational and reflection Symmetry (LDRRS) can be carried out via system ODEs along these curves. However, 3+1 Numerical Relativity computations demonstrate this is not case, we show analytically due to presence tensorial quantity which suppressed by symmetry. calculate term analytically, verify...
Novel applications of Numerical Relativity demand more flexible algorithms and tools. In this paper, I develop test a multigrid solver, based on the infrastructure provided by Einstein Toolkit, for elliptic partial differential equations spaces with periodic boundary conditions (PBCs). This type often characterizes numerical representation cosmological models, where space is assumed to be made up identical copies single fiducial domain, so that only finite volume (with PBCs at its edges)...
The applications of numerical relativity to cosmology are on the rise, contributing insight into such cosmological problems as structure formation, primordial phase transitions, gravitational-wave generation, and inflation. In this paper, I present infrastructure for computation inhomogeneous dust cosmologies which was used recently measure effect nonlinear inhomogeneity cosmic expansion rate. illustrate code's architecture, provide evidence its correctness in a number familiar settings,...
Physics-informed neural networks (NN) are an emerging technique to improve spatial resolution and enforce physical consistency of data from physics models or satellite observations. A super-resolution (SR) is explored reconstruct high-resolution images ($4\times$) lower in advection-diffusion model atmospheric pollution plumes. SR performance generally increased when the equation constrains NN addition conventional pixel-based constraints. The ability techniques also missing investigated by...
It has been recently shown that, contrary to an intuitive decoupling argument, the presence of new physics at very large energy scales (say around Planck scale) can have a strong impact on electroweak vacuum lifetime. In particular, could be totally destabilized. This study was performed in flat spacetime background, and it is important extend analysis curved since these are Planckian-physics effects. generally expected that under extreme conditions gravity should quench formation true...
The Higgs effective potential becomes unstable at approximately $10^{11}$ GeV, and if only standard model interactions are considered, the lifetime $τ$ of electroweak vacuum turns out to be much larger than age Universe $T_U$. It is well known, however, that extremely sensitive presence unknown new physics: latter can enormously lower $τ$. This poses a serious problem for stability our Universe, demanding physical mechanism protects it from disastrous decay. We have found there exists...
The peeling theorem of general relativity predicts that the Weyl curvature scalars ${\ensuremath{\Psi}}_{n}$ ($n=0,\dots{},4$), when constructed from a suitable null tetrad in an asymptotically flat spacetime, fall off as ${r}^{n\ensuremath{-}5}$ along outgoing radial geodesics. This leads to interpretation ${\ensuremath{\Psi}}_{4}$ gravitational radiation at large distances source. We have performed numerical simulations full binary black hole inspiral and merger, computed standard used...
We present results obtained by scattering a scalar field off the curved background of coalescing binary black hole system. A massless is evolved on set fixed backgrounds, each provided spatial hypersurface generated numerically during merger. show that scattered from merger region exhibits quasinormal ringing once common apparent horizon surrounds two holes. This occurs earlier than onset perturbative regime as measured start in gravitational waveforms. also use frequencies to associate mass...
Scientific computation faces multiple scalability challenges in trying to take advantage of the latest generation compute, network and graphics hardware. We present a comprehensive approach solving four important challenges: programming productivity, large numbers of processors, I/O bandwidth, interactive visualization large data. describe scenario where our integrated system is applied the field numerical relativity. A solver for governing Einstein equations generated and ...
This paper describes the Alpaca runtime tools. These tools leverage component infrastructure of Cactus Framework in a novel way to enable steering, monitoring, and interactive control simulation. Simulation data can be observed graphically, or by inspecting values variables. When GPUs are available, images generated using volume ray casting on live data. In response error conditions automatic triggers, users pause simulation modify repair data, change parameters. this we describe design our...