Eugene Vasiliev home page

Action/angle modelling

E.Vasiliev, "AGAMA: Action-based galaxy modelling architecture" (MNRAS 2019)

Action-based modelling (talk at the 3rd Gaia Challenge, Barcelona, September 2015)

Action-based self-consistent models (talk at the University of Surrey, May 2016), and a shorter version presented at the workshop Secular evolution of self-gravitating systems workshop (Paris, May 2016)

AGAMA: Action-based galaxy modelling architecture (talk at the 4th Gaia Challenge, Stockholm, October 2016)

Self-consistent models of our Galaxy in the Gaia era (talk at the University of Barcelona, October 2017), and an updated version of the talk (Strasbourg, March 2018)

Defying the disequilibrium: the usefulness of steady-state self-consistent models for the Galaxy (talk at the KITP conference In the Balance: Stasis and Disequilibrium in the Milky Way, Santa Barbara, April 2019; video recording)

Stellar-dynamical modelling with the Agama toolbox (talk at ARI Heidelberg, November 2022)

Galactic dynamics with Agama (talk at the Challenges and Innovations in Computational Astrophysics-V workshop, November 2023; video recording)

A more in-depth tutorial on galactic dynamics with Agama: foundations and applications (lectures at the MWGaiaDN Galaxy modelling workshop workshop, Guildford, December 2024)

Agama — action-based galaxy modelling library.

Simulations of self-gravitating systems (galaxies, nuclear star clusters)

E.Vasiliev, "A new Monte Carlo method for dynamical evolution of non-spherical stellar systems" (MNRAS 2015)

E.Vasiliev, "A new Fokker–Planck approach for relaxation-driven evolution of galactic nuclei" (ApJ 2017)

Q.Zhu, E.Vasiliev, Y.Li, Y.Jing, "Primordial black holes as dark matter: constraints from compact ultra-faint dwarfs" (MNRAS 2018)

J.Sanders, E.Lilley, E.Vasiliev, N.W.Evans, D.Erkal, "Models of distorted and evolving dark matter haloes" (MNRAS 2020)

E.Vasiliev, V.Belokurov, N.W.Evans, "Radialization of satellite orbits in galaxy mergers" (ApJL 2022)

C.A.Dong-Paez, E.Vasiliev, N.W.Evans, "A 6-d view of stellar shells" (MNRAS 2022)

T.Tepper-Garcia, J.Bland-Hawthorn, E.Vasiliev, E.Athanassoula, O.Gerhard, A.Quillen, P.McMillan, K.Freeman, G.Lewis, R.Teyssier, S.Sharma, M.Hayden, S.Buder, "A barred Milky Way surrogate from an N-body simulation"; simulation snapshots

E.Davies, E.Vasiliev, V.Belokurov, N.W.Evans, A.Dillamore, "Ironing the folds: The phase-space chevrons of a GSE-like merger as a dark matter subhalo detector" (MNRAS 2023)

E.Davies, A.Dillamore, E.Vasiliev, V.Belokurov, "Accelerated phase mixing in the stellar halo due to a rotating bar" (MNRASL 2023)

P.Galan-de Anta, E.Vasiliev, M.Sarzi, M.Dotti, P.Capelo, A.Incatasciato, L.Posti, L.Morelli, E.Corsini, "The fragility of thin discs in galaxies - I. Building tailored N-body galaxy models" (MNRAS 2023)

P.Galan-de Anta, P.Capelo, E.Vasiliev, M.Dotti, M.Sarzi, E.Corsini, L.Morelli, "The fragility of thin discs in galaxies - II. Thin discs as tracers of the assembly history of galaxies" (MNRAS 2023)

T.Tepper-Garcia, J.Bland-Hawthorn, E.Vasiliev, O.Agertz, R.Teyssier, C.Federrath, "Nexus: A framework for simulations of idealised galaxies" (MNRAS 2024)

G.Hunter, M.Sormani, J.Beckmann, E.Vasiliev, S.Glover, R.Klessen, J.Soler, N.Brucy, P.Girichidis, J.Goller, L.Ohlin, R.Tress, S.Molinari, O.Gerhard, M.Benedettini, R.Smith, P.Hennebelle, L.Testi, "Testing kinematic distances under a realistic Galactic potential" (A&A, in press)

L.Beraldo e Silva, M.Valluri, E.Vasiliev, K.Hattori, W.de Siqueira Pedra, K.Daniel, "Minimum-entropy constraints on galactic potentials" (submitted)

Secular Monte-Carlo method (poster at Institut Henri Poincare, November 2013)

A new Monte-Carlo method for dynamical evolution of non-spherical stellar systems (talk at the MODEST-14 meeting, Bad Honnef, June 2014)

Monte-Carlo methods in stellar dynamics, in application to massive black holes in galactic nuclei (talk at LPI, September 2014)

Adventures of a stellar cusp in the Galactic center (talk at the MODEST-17 meeting, Prague, September 2017)

Beyond collisionless Boltzmann equation: when relaxation is important (talk at the Vlasov workshop, Marseille, November 2017)

Radialization of satellite orbits in galaxy mergers (talk at the SEGal seminar series, Paris, September 2021)

The Galactic strudel (seminar at the Institute of Astronomy, Cambridge, October 2022)

Kinetics for gravity (talk at the KITP workshop Interconnections between the Physics of Plasmas and Self-gravitating Systems, Santa Barbara, June 2024)

Raga — a software for Monte Carlo simulations of non-spherical stellar systems, possibly containing massive black holes.

PhaseFlow — a Fokker–Planck code for spherically-symmetric isotropic multicomponent stellar systems, possibly containing a massive black hole.

Introduction and tutorial for gravitational N-body simulations (for undergraduates, Spring 2013): Lecture notes and problems.

Numerical simulations of gravitational dynamics (lectures at the School of Modern Astrophysics, Moscow, June 2016): Lectures, Seminars.

Lecture 1: Astrophysical introduction to gravitational dynamics.
Basic concepts: mean-field regime, two-body relaxation, collective effects, secular evolution.
Physical regimes: collisional vs. collisionless.
Overview of gravitational N-body problem, computational challenges.
Astrophysical contexts: planetary systems, star clusters, galactic dynamics, cosmological structure formation.
Lecture 2: Collisional systems — planetary systems and star clusters.
Direct-summation methods. Symplectic and Hermite integration methods. Choice of timestep.
Two-body regularization schemes and their extensions.
Secular evolution of near-Keplerian systems, orbit-averaged approach.
Long-term evolution of planetary systems and globular clusters.
Lecture 3: Collisionless systems — galaxies and cosmology.
Force softening and its physical interpretation; resolution and convergence.
Tree-code and fast multipole methods.
Grid-based Poisson solvers (FFT and multigrid relaxation methods), adaptive mesh refinements schemes.
Basis-set expansion technique.
Cosmology: comoving coordinates, initial conditions, halo finders.
Lecture 4: Unconventional approaches and miscellaneous other issues.
Computational issues: hardware acceleration, GPU, parallelization strategies.
Direct solution of collisionless Boltzmann equation, applications to dark matter dynamics in cosmology.
Fokker-Planck and Monte Carlo methods for collisional systems.
Hydrodynamics — main approaches: grid-based, SPH, moving-mesh.
Gastrophysics and sub-grid physics in cosmological context.
Seminar 1: Overview of gravitational N-body simulation software.
Workflow of numerical simulations. Individual simulation codes and integrated frameworks: NEMO, Starlab, AMUSE.
Architecture of the AMUSE framework. Setting up and testing the simulation environment on laptops.
Creating and analyzing a simple N-body model.
Seminar 2: Simulations of collisional systems.
First-hand experience with various integration schemes. Assessing the validity of simulations, error control.
Evolving a star cluster and the Solar system.
Seminar 3. Simulations of collisionless systems.
Dynamical friction acting on a point-mass satellite orbiting in a galaxy.
Seminar 4. Bridge coupling of individual integrators.
Star cluster orbiting in a galaxy. Tidal stripping and dissolution acting together with dynamical friction.

Dark matter halo structure and evolution

PhD thesis: «Dynamics of dark matter in galactic centers» (in Russian). Abstract, Автореферат, диссертация

The evolution of dark matter in central areas of galaxies is considered (Milky Way is taken as an example). The formation of a galaxy leads to the compression of dark matter halo due to baryonic infall. Traditional method of calculating the compression (Blumenthal method) is shown to overestimate the dark matter density, especially for more flat initial halo density profiles and for radially anisotropic particle velocities. Subsequent evolution is driven by scattering off of dark matter particles on bulge stars and their absorption by the supermassive black hole. It is described by diffusion equation in energy - angular momentum phase space. The diffusion coefficients are calculated, as well as the absoroption and evaporation rate of particles. It is shown that by now the density of dark matter inside central parsec is greatly diminished: approximately 10% of initial dark matter mass is captured by black hole, about a half is evaporated. The annihilation of particles may explain observed gamma-ray flux from Galactic center

Its results are mainly presented in the following papers:

E.Vasiliev, M.Zelnikov, "Dark matter dynamics in the galactic center" (Phys.Rev.D 2008)

E.Vasiliev, "Dark matter annihilation near a black hole: Plateau versus weak cusp" (Phys.Rev.D 2007)

E.Vasiliev, "A simple analytical model for dark matter halo structure and adiabatic contraction" (JETP 2006)

Dark matter dynamics in the Galactic center (poster at the Dynamics of Galaxies conference, Saint-Petersburg, August 2007)

Dark matter dynamics in the Galactic center (talk at the N-body school, Turku, August 2008)