Articles

A new hybrid technique for modeling dense star clusters

The “gravitational million-body problem,” to model the dynamical evolution of a self-gravitating, collisional N-body system with ∼10⁶ particles over many relaxation times, remains a major challenge in computation...

Authors: Carl L. Rodriguez, Bharath Pattabiraman, Sourav Chatterjee, Alok Choudhary, Wei-keng Liao, Meagan Morscher and Frederic A. Rasio

Fast cosmic web simulations with generative adversarial networks

Dark matter in the universe evolves through gravity to form a complex network of halos, filaments, sheets and voids, that is known as the cosmic web. Computational models of the underlying physical processes, ...

Authors: Andres C. Rodríguez, Tomasz Kacprzak, Aurelien Lucchi, Adam Amara, Raphaël Sgier, Janis Fluri, Thomas Hofmann and Alexandre Réfrégier

Observing supermassive black holes in virtual reality

We present a 360^∘ (i.e., 4π steradian) general-relativistic ray-tracing and radiative transfer calculations of accreting supermassive black holes. We perform state-of-the-art three-dimensional general-relativisti...

Authors: Jordy Davelaar, Thomas Bronzwaer, Daniel Kok, Ziri Younsi, Monika Mościbrodzka and Heino Falcke

On the parallelization of stellar evolution codes

Multidimensional nucleosynthesis studies with hundreds of nuclei linked through thousands of nuclear processes are still computationally prohibitive. To date, most nucleosynthesis studies rely either on hydros...

Authors: David Martin, Jordi José and Richard Longland

A MODEST review

We present an account of the state of the art in the fields explored by the research community invested in “Modeling and Observing DEnse STellar systems”. For this purpose, we take as a basis the activities of...

Authors: Anna Lisa Varri, Maxwell Xu Cai, Francisca Concha-Ramírez, František Dinnbier, Nora Lützgendorf, Václav Pavlík, Sara Rastello, Antonio Sollima, Long Wang and Alice Zocchi

Entropy-limited hydrodynamics: a novel approach to relativistic hydrodynamics

We present entropy-limited hydrodynamics (ELH): a new approach for the computation of numerical fluxes arising in the discretization of hyperbolic equations in conservation form. ELH is based on the hybridisat...

Authors: Federico Guercilena, David Radice and Luciano Rezzolla

PKDGRAV3: beyond trillion particle cosmological simulations for the next era of galaxy surveys

Authors: Douglas Potter, Joachim Stadel and Romain Teyssier

The black hole accretion code

We present the black hole accretion code (BHAC), a new multidimensional general-relativistic magnetohydrodynamics module for the MPI-AMRVAC framework. BHAC has been designed to solve the equations of ideal genera...

Authors: Oliver Porth, Hector Olivares, Yosuke Mizuno, Ziri Younsi, Luciano Rezzolla, Monika Moscibrodzka, Heino Falcke and Michael Kramer

The evolution of hierarchical triple star-systems

Field stars are frequently formed in pairs, and many of these binaries are part of triples or even higher-order systems. Even though, the principles of single stellar evolution and binary evolution, have been ...

Authors: Silvia Toonen, Adrian Hamers and Simon Portegies Zwart

Riemann solvers and Alfven waves in black hole magnetospheres

In the magnetosphere of a rotating black hole, an inner Alfven critical surface (IACS) must be crossed by inflowing plasma. Inside the IACS, Alfven waves are inward directed toward the black hole. The majority...

Authors: Brian Punsly, Dinshaw Balsara, Jinho Kim and Sudip Garain

In situ and in-transit analysis of cosmological simulations

Modern cosmological simulations have reached the trillion-element scale, rendering data storage and subsequent analysis formidable tasks. To address this circumstance, we present a new MPI-parallel approach fo...

Authors: Brian Friesen, Ann Almgren, Zarija Lukić, Gunther Weber, Dmitriy Morozov, Vincent Beckner and Marcus Day

Achieving convergence in galaxy formation models by augmenting N-body merger trees

Accurate modeling of galaxy formation in a hierarchical, cold dark matter universe requires the use of sufficiently high-resolution merger trees to obtain convergence in the predicted properties of galaxies. W...

Authors: Andrew J Benson, Chris Cannella and Shaun Cole

Simulations of stripped core-collapse supernovae in close binaries

We perform smoothed-particle hydrodynamical simulations of the explosion of a helium star in a close binary system, and study the effects of the explosion on the companion star as well as the effect of the pre...

Authors: Alex Rimoldi, Simon Portegies Zwart and Elena Maria Rossi

Efficient conservative ADER schemes based on WENO reconstruction and space-time predictor in primitive variables

We present a new version of conservative ADER-WENO finite volume schemes, in which both the high order spatial reconstruction as well as the time evolution of the reconstruction polynomials in the local space-...

Authors: Olindo Zanotti and Michael Dumbser

Stationary relativistic jets

In this paper we describe a simple numerical approach which allows to study the structure of steady-state axisymmetric relativistic jets using one-dimensional time-dependent simulations. It is based on the fac...

Authors: Serguei S Komissarov, Oliver Porth and Maxim Lyutikov

Sapporo2: a versatile direct N-body library

Astrophysical direct N-body methods have been one of the first production algorithms to be implemented using NVIDIA’s CUDA architecture. Now, almost seven years later, the GPU is the most used accelerator device ...

Authors: Jeroen Bédorf, Evghenii Gaburov and Simon Portegies Zwart

Implicit large eddy simulations of anisotropic weakly compressible turbulence with application to core-collapse supernovae

In the implicit large eddy simulation (ILES) paradigm, the dissipative nature of high-resolution shock-capturing schemes is exploited to provide an implicit model of turbulence. The ILES approach has been appl...

Authors: David Radice, Sean M Couch and Christian D Ott

GPU-enabled particle-particle particle-tree scheme for simulating dense stellar cluster system

Authors: Masaki Iwasawa, Simon Portegies Zwart and Junichiro Makino

PHEW: a parallel segmentation algorithm for three-dimensional AMR datasets

We introduce phew (Parallel HiErarchical Watershed), a new segmentation algorithm to detect structures in astrophysical fluid simulations, and its implementation into the adaptive mesh refinement (AMR) code ramse...

Authors: Andreas Bleuler, Romain Teyssier, Sébastien Carassou and Davide Martizzi

A calculator for Roche lobe properties

The Roche lobe geometry is important to understand and study the properties of the mass-losing component in a semi-detached binary system. However it is not easy to calculate accurately, and existing tables us...

Authors: Denis A Leahy and Janet C Leahy

The numerical frontier of the high-redshift Universe

The first stars are believed to have formed a few hundred million years after the big bang in so-called dark matter minihalos with masses

Authors: Thomas H Greif

Adaptive techniques for clustered N-body cosmological simulations

ChaNGa is an N-body cosmology simulation application implemented using Charm++. In this paper, we present the parallel design of ChaNGa and address many challenges arising due to the high dynamic...

Authors: Harshitha Menon, Lukasz Wesolowski, Gengbin Zheng, Pritish Jetley, Laxmikant Kale, Thomas Quinn and Fabio Governato

On the reliability of N-body simulations

The general consensus in the N-body community is that statistical results of an ensemble of collisional N-body simulations are accurate, even though individual simulations are not. A way to test this hypothesis i...

Authors: Tjarda Boekholt and Simon Portegies Zwart

A fast multipole method for stellar dynamics

The approximate computation of all gravitational forces between N interacting particles via the fast multipole method (FMM) can be made as accurate as direct summation, but requires less than ...

Authors: Walter Dehnen

On the origin of jets from disc-accreting magnetized stars

A brief review of the origin of jets from disc-accreting rotating magnetized stars is given. In most models, the interior of the disc is characterized by a turbulent viscosity and magnetic diffusivity (‘alpha’...

Authors: Richard VE Lovelace, Marina M Romanova, Patrick Lii and Sergei Dyda

Artificial viscosity in comoving curvilinear coordinates: towards a differential geometrically consistent implicit advection scheme

We propose a modification for the tensor of artificial viscosity employable for generally comoving, curvilinear grids. We present a strong conservation form for the equations of radiation hydrodynamics for stu...

Authors: Harald Höller, Antti Koskela, Ernst Dorfi and Werner Benger