The Orbital Evolution Induced by Baryonic Condensation in Triaxial Halos

Abstract

Using spectral methods, we analyse the orbital structure of prolate/triaxial dark matter (DM) halos in N-body simulations to understand the processes that drive the evolution of shapes of DM halos and elliptical galaxies in which central masses are grown. A longstanding issue is whether the change in the shapes of DM halos is the result of chaotic scattering of box orbits, or whether they change shape adiabatically in response to the evolving galactic potential. We use orbital frequencies to classify orbits, to quantify orbital shapes, and to identify resonant orbits and chaotic orbits. The frequency-based method overcomes the limitations of Lyapunov exponents which are sensitive to numerical discreteness effects. Regardless of the distribution of the baryonic component, the shape of a DM halo changes primarily due to changes in the shapes of individual orbits within a given family. Orbits with small pericentric radii are more likely to change both their orbital type and shape than orbits with large pericentric radii. Whether the evolution is regular (and reversible) or chaotic (and irreversible), depends primarily on the radial distribution of the baryonic component. The growth of an extended baryonic component of any shape results in a regular rather than chaotic change in orbital populations. In contrast the growth of a massive and compact central component results in chaotic scattering of a significant fraction of both box and long-axis tube orbits. The growth of a disk causes a significant fraction of halo particles to become trapped by major global orbital resonances. Despite the fact that shape of a DM halo is always quite oblate following the growth of a central baryonic component, a significant fraction of its orbit population has characteristics of its triaxial or prolate progenitor (ABRIDGED).

23 pages, 14 Figures, Version accepted by MNRAS. New model added - no changes to conclusions

References in corpus (5)

• The Causes of Halo Shape Changes Induced by Cooling Baryons: Disks Versus Substructures
• The Hot Interstellar Medium of Normal Elliptical Galaxies. I. A Chandra Gas Gallery and Comparison of X-ray and Optical Morphology
• The Flattened Dark Matter Halo of M31 as Deduced from the Observed HI Scale Heights
• Multimass spherical structure models for N-body simulations
• The rate of secular evolution in elliptical galaxies with central masses

Cited by in corpus (69)

• AGAMA: Action-based galaxy modelling architecture
• The Sagittarius Dwarf Galaxy: a Model for Evolution in a Triaxial Milky Way Halo
• Double-Disk Dark Matter
• Supermassive Black Hole Binary Evolution in Axisymmetric Galaxies: the final parsec problem is not a problem
• The Shape of Dark Matter Haloes in the Aquarius Simulations: Evolution and Memory
• Orbital structure of merger remnants: Trends with gas fraction in 1:1 mergers
• On the identification of merger debris in the {\it Gaia} Era
• Cosmological Simulations of Decaying Dark Matter: Implications for Small-scale Structure of Dark Matter Halos
• Chaotic Dispersal of Tidal Debris
• What's Up in the Milky Way? The Orientation of the Disc Relative to the Triaxial Halo
• The Sphericalization of Dark Matter Halos by Galaxy Disks
• Supermassive Dark Stars: Detectable in JWST
• Dark Stars: A Review
• Shapes of Gas, Gravitational Potential and Dark Matter in Lambda-CDM Clusters
• The impact of baryon physics on the structure of high-redshift galaxies
• A unified framework for the orbital structure of bars and triaxial ellipsoids
• The impact of baryons on the direct detection of dark matter
• An analytical model for the accretion of dark matter subhalos
• Regular and chaotic orbits in barred galaxies - I. Applying the SALI/GALI method to explore their distribution in several models
• Streams in the Aquarius stellar haloes
• A new code for orbit analysis and Schwarzschild modelling of triaxial stellar systems
• Probing the shape and history of the Milky Way halo with orbital spectral analysis
• Anatomy of a buckling galactic bar
• Actions, angles and frequencies for numerically integrated orbits
• Dynamically constraining the length of the Milky Way bar
• On the orbits that generate the X-shape in the Milky Way bulge
• A fast algorithm for estimating actions in triaxial potentials
• Observing Dark Stars with JWST
• The Clustering of Orbital Poles Induced by the LMC: Hints for the Origin of Planes of Satellites
• Action-based distribution function modelling for constraining the shape of the Galactic dark matter halo
• Loss of halo triaxiality due to bar formation
• Stellar Disks in Aquarius Dark Matter Haloes
• Faint objects in motion: the new frontier of high precision astrometry
• Milking the spherical cow: on aspherical dynamics in spherical coordinates
• Chaos and dynamical trends in barred galaxies: bridging the gap between N-body simulations and time-dependent analytical models
• Influence of baryons on the orbital structure of dark matter haloes
• Internal Alignments of Red Versus Blue Discs in Dark Matter Halos
• Systematic Problems With Using Dark Matter Simulations to Model Stellar Halos
• Orbital support and evolution of flat profiles of bars (shoulders)
• The Orbital Structure of Triaxial Galaxies with Figure Rotation
• Baryonic impact on the dark matter orbital properties of Milky Way-sized haloes
• On the relevance of chaos for halo stars in the Solar Neighbourhood
• Baryons Shaping Dark Matter Haloes
• Chaotic motion and the evolution of morphological components in a time-dependent model of a barred galaxy within a dark matter halo
• Orbital classification in an N-body bar
• Halo orbits in cosmological disk galaxies: tracers of formation history
• FCC046: a candidate gaseous polar ring dwarf elliptical galaxy in the Fornax Cluster
• Constraining Dark Matter Properties with Gamma-Rays from the Galactic Center with Fermi-LAT
• Substructures, Resonances and debris streams
• Constraining the Milky Way Dark Matter Density Profile with Gamma-Rays with Fermi-LAT
• Constructing the Milky Way Stellar Halo in the Galactic Center by Direct Orbit Integration
• Frequencies, chaos and resonances: a study of orbital parameters of nearby thick disc and halo stars
• Chaotic mixing and the secular evolution of triaxial cuspy galaxy models built with Schwarzschild's method
• Detectability of Supermassive Dark Stars with the Roman Space Telescope
• Angular Momentum Evolution in Dark Matter Halos
• On the chaos induced by the Galactic bar on the orbits of nearby halo stars
• Stability and pulsation of the first dark stars
• Made-To-Measure Models of Self-Similar Triaxial Halos with Steep Inner Density Gradients
• First measurement of the triaxiality of the inner dark matter halo of the Milky Way
• Effective power-law dependence of Lyapunov exponents on the central mass in galaxies
• Orbits and adiabatic contraction in scalar field dark matter halos: revisiting the cusp-core problem in dwarf galaxies
• Massive evaluation and analysis of Poincaré recurrences on grids of initial data: a tool to map chaotic diffusion
• Early Growing Supermassive Black Holes Strengthen Bars and Boxy/Peanut Bulges
• The Stellar Orbital Structure in Axisymmetric Galaxy Models with Supermassive Black Hole Binaries
• The Spheroidal Bulge of the Milky Way: Chemodynamically Distinct from the Inner-Thick Disc and Bar
• Supermassive Dark Stars and their remnants as a possible solution to three recent cosmic dawn puzzles
• Stellar orbital properties as diagnostics of the origin of the stellar halo
• New tools for probing the phase space structure of dark matter halos
• Deprojection of external barred galaxies from photometry