Simulations of the Milky Way’s central molecular zone – I. Gas dynamics

Tress, Robin G., Sormani, Mattia C., Glover, Simon C. O., Klessen, Ralf S., Battersby, Cara D., Clark, Paul C. ORCID: https://orcid.org/0000-0002-4834-043X, Hatchfield, H. Perry and Smith, Rowan J. 2020. Simulations of the Milky Way’s central molecular zone – I. Gas dynamics. Monthly Notices of the Royal Astronomical Society 499 (3) , pp. 4455-4478. 10.1093/mnras/staa3120

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Abstract

We use hydrodynamical simulations to study the Milky Way’s central molecular zone (CMZ). The simulations include a non-equilibrium chemical network, the gas self-gravity, star formation, and supernova feedback. We resolve the structure of the interstellar medium at sub-parsec resolution while also capturing the interaction between the CMZ and the bar-driven large-scale flow out to R∼5kpc⁠. Our main findings are as follows: (1) The distinction between inner (R ≲ 120 pc) and outer (120 ≲ R ≲ 450 pc) CMZ that is sometimes proposed in the literature is unnecessary. Instead, the CMZ is best described as single structure, namely a star-forming ring with outer radius R ≃ 200 pc which includes the 1.3° complex and which is directly interacting with the dust lanes that mediate the bar-driven inflow. (2) This accretion can induce a significant tilt of the CMZ out of the plane. A tilted CMZ might provide an alternative explanation to the ∞-shaped structure identified in Herschel data by Molinari et al. (3) The bar in our simulation efficiently drives an inflow from the Galactic disc (R ≃ 3 kpc) down to the CMZ (R ≃ 200 pc) of the order of 1M⊙yr−1⁠, consistent with observational determinations. (4) Supernova feedback can drive an inflow from the CMZ inwards towards the circumnuclear disc of the order of ∼0.03M⊙yr−1⁠. (5) We give a new interpretation for the 3D placement of the 20 and 50 km s−1 clouds, according to which they are close (R ≲ 30 pc) to the Galactic Centre, but are also connected to the larger scale streams at R ≳ 100 pc.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	Oxford University Press
ISSN:	0035-8711
Date of First Compliant Deposit:	10 December 2020
Date of Acceptance:	6 October 2020
Last Modified:	09 Nov 2022 09:46
URI:	https://orca.cardiff.ac.uk/id/eprint/136928

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