A barred Milky Way surrogate from an N-body simulation

Abstract

We present an N-body model for the barred Milky Way (MW) galaxy that reproduces many of its properties, including the overall mass distribution, the disc kinematics, and the properties of the central bar. Our high-resolution (N ∼ 10 8 particles) simulation, performed with the ramses code, starts from an axisymmetric non-equilibrium configuration constructed within the agama framework. This is a self-consistent dynamical model of the MW defined by the best available parameters for the dark matter halo, the stellar disc and the bulge.For the known (stellar+gas) disc mass (4.5 ± 1.5 × 10 10 M ) and disc mass fraction at R ≈ 2.2R d ( f d ≈ 0.3 − 0.6), the low mass limit does not yield a bar in a Hubble time. The high mass limit adopted here produces a box/peanut bar within about 2 Gyr with the correct mass (M bar ∼ 10 10 M ), size (R bar ≈ 5 kpc) and peak pattern speed (Ω bar ≈ 40 − 45 km s −1 kpc −1 ). In agreement with earlier work, the bar formation timescale scales inversely with f d (i.e. log T bar (Gyr) ≈ 0.60/ f d − 0.83, 1 f d 0.3). The disc radial heating is strong, but, in contrast to earlier claims, we find that disc vertical heating outside of the box/peanut (b/p) bulge structure is negligible.The synthetic barred MW exhibits long-term stability, except for the slow decline ( Ωbar ≈ −2 km s −1 kpc −1 Gyr −1 ) of the bar pattern speed, consistent with recent estimates. If our model is indicative of the Milky Way, we estimate that the bar first emerged 3 − 4 Gyr ago.

Kinematic-Chemical analysis and Time tagging for the Diagonal Ridge Structure of the Galactic Outer Disk with LAMOST Red Giant Branch Stars

“…Galactic seismology is the inference of the Galactic potential and Galactic sub-structure from a dynamical analysis of the observed perturbations in the gas or stellar component (discs) of the Milky Way (Chakrabarti 2017;Bland-Hawthorn & Tepper-García 2021) 1 , which is also characterising the Milky Way that is non-equilibrium and non-stationary in the asymmetric potential, and will undoubtedly give us a more comprehensive understanding of the dynamic origin and evolution of the Galaxy (Widrow et al 2012;Carlin et al 2013;Widrow et al 2014;Liu et al 2018;Wang et al 2018aWang et al ,b, 2019Wang et al , 2020aLópez-Corredoira & Sylos Labini 2019;López-Corredoira, Garzón & Wang et al 2020;Trick et al 2019;Yu, Wang & Cui et al 2021;Tepper-Garcia et al 2021;Wang et al 2022a,b;Tepper-Garcia et al 2022).…”

Dynamically constraining the length of the Milky Way bar

“…The primary simulation we use (hereafter Galaxy A) is a reproduction of the MWP14-3 model from . We also make use of another Milky Way-like simulation (hereafter Galaxy B) from Tepper-Garcia et al (2021) to further validate our method and compare to Milky Way observational data.…”

“…Although it is also set up to mirror the Milky Way, Galaxy B has significantly different initial conditions than Galaxy A. For a complete description of Galaxy B, we refer the reader to Tepper-Garcia et al (2021). In short, Galaxy B is set up using the Action-based GAlaxy Modelling Architechture software package (AGAMA; Vasiliev 2019).…”

Gaia Data Release 3

“…Other recent works focused on how the spiral arms or a Galactic bar change the expected radial, tangential, and vertical kinematic maps (i.e. Faure et al 2014;Monari et al 2016;Hunt & Bovy 2018;Monari et al 2019;Tepper-Garcia et al 2021), based on either test particle simulations or pure N-body simulations. The observable used to compare with the data can either be directly mapping the average or dispersions of the velocity components on the Galactic plane, or checking the known moving groups in the solar neighbourhood or the ridges in the diagram of azimuthal velocity versus radius.…”