Simulations of the Milky Way’s central molecular zone — I. Gas dynamics. (arXiv:2004.06724v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Tress_R/0/1/0/all/0/1">Robin G. Tress</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sormani_M/0/1/0/all/0/1">Mattia C. Sormani</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Glover_S/0/1/0/all/0/1">Simon C.O. Glover</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Klessen_R/0/1/0/all/0/1">Ralf S. Klessen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Battersby_C/0/1/0/all/0/1">Cara D. Battersby</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Clark_P/0/1/0/all/0/1">Paul C. Clark</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hatchfield_H/0/1/0/all/0/1">H Perry Hatchfield</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Smith_R/0/1/0/all/0/1">Rowan J. Smith</a>
We use hydrodynamical simulations to study the Milky Way’s central molecular
zone (CMZ), i.e. the star-forming nuclear ring at Galactocentric radii
$Rlesssim200$ pc. The simulations comprise the gas flow in a Milky Way barred
potential out to $R=5$ kpc, which is necessary in order to capture the
large-scale environment in which the CMZ is embedded and with which it is
strongly interacting through the bar-driven inflow. The simulations also
include a non-equilibrium time-dependent chemical network, gas self-gravity,
and a sub-grid model for star formation and supernova feedback, all while
reaching sub-parsec resolution in the densest regions. Our main findings are as
follows: (1) The distinction between inner ($Rlesssim120$ pc) and outer
($120lesssim Rlesssim450$ 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 $Rsimeq 200$ pc which
is interacting directly 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 $infty$-shaped
structure identified in Herschel data by Molinari et al. 2011. (3) The bar in
our simulation efficiently drives an inflow from the Galactic disc ($Rsimeq 3$
kpc) down to the CMZ ($Rsimeq200$ pc) of the order of
$1rm,M_odot,yr^{-1}$, consistent with observational determinations. (4)
Self-gravity and supernovae feedback can drive an inflow from the CMZ inwards
towards the circumnuclear disc of the order of $sim0.03,rm
M_odot,yr^{-1}$. (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 ($Rlesssim30$
pc) to the Galactic centre, but are also connected to the larger-scale streams
at $Rgtrsim100$ pc.
We use hydrodynamical simulations to study the Milky Way’s central molecular
zone (CMZ), i.e. the star-forming nuclear ring at Galactocentric radii
$Rlesssim200$ pc. The simulations comprise the gas flow in a Milky Way barred
potential out to $R=5$ kpc, which is necessary in order to capture the
large-scale environment in which the CMZ is embedded and with which it is
strongly interacting through the bar-driven inflow. The simulations also
include a non-equilibrium time-dependent chemical network, gas self-gravity,
and a sub-grid model for star formation and supernova feedback, all while
reaching sub-parsec resolution in the densest regions. Our main findings are as
follows: (1) The distinction between inner ($Rlesssim120$ pc) and outer
($120lesssim Rlesssim450$ 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 $Rsimeq 200$ pc which
is interacting directly 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 $infty$-shaped
structure identified in Herschel data by Molinari et al. 2011. (3) The bar in
our simulation efficiently drives an inflow from the Galactic disc ($Rsimeq 3$
kpc) down to the CMZ ($Rsimeq200$ pc) of the order of
$1rm,M_odot,yr^{-1}$, consistent with observational determinations. (4)
Self-gravity and supernovae feedback can drive an inflow from the CMZ inwards
towards the circumnuclear disc of the order of $sim0.03,rm
M_odot,yr^{-1}$. (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 ($Rlesssim30$
pc) to the Galactic centre, but are also connected to the larger-scale streams
at $Rgtrsim100$ pc.
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