The life cycle of the Central Molecular Zone – II. Distribution of atomic and molecular gas tracers

Armillotta, Lucia; Krumholz, Mark R.; Teodoro, Enrico M. Di

doi:10.1093/mnras/staa469

Cited by 28 publications

(14 citation statements)

References 94 publications

(150 reference statements)

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“…In contrast, the default particle mass in Armillotta et al (2019) is 2000 M , a factor of 1000 worse than we achieve here. Armillotta et al (2019) and Armillotta, Krumholz & Di Teodoro (2020) also present results from a 'high-resolution' run with a particle mass of 200 M , which they carried out for a much shorter period than their main run, but even this has a much worse resolution than our simulation. An important consequence of this difference in resolution is that in the Armillotta et al (2019) simulation, the Sedov-Taylor phase following an SN explosion is resolved only for SNe exploding in low-density gas with n < 1 cm −3 , whereas in our simulation it remains well resolved even for SNe exploding in gas with a density close to our sink creation threshold.…”

Section: What Drives the Time Variability Of The Sfr In The Cmz?mentioning

confidence: 77%

Simulations of the Milky Way’s Central Molecular Zone – II. Star formation

Sormani

Treß

Glover

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Abstract The Milky Way’s central molecular zone (CMZ) has emerged in recent years as a unique laboratory for the study of star formation. Here we use the simulations presented in Tress et al. 2020 to investigate star formation in the CMZ. These simulations resolve the structure of the interstellar medium at sub-parsec resolution while also including the large-scale flow in which the CMZ is embedded. Our main findings are as follows. (1) While most of the star formation happens in the CMZ ring at R ≳ 100 pc, a significant amount also occurs closer to SgrA* at R ≲ 10 pc. (2) Most of the star formation in the CMZ happens downstream of the apocentres, consistent with the “pearls-on-a-string” scenario, and in contrast to the notion that an absolute evolutionary timeline of star formation is triggered by pericentre passage. (3) Within the timescale of our simulations (∼100 Myr), the depletion time of the CMZ is constant within a factor of ∼2. This suggests that variations in the star formation rate are primarily driven by variations in the mass of the CMZ, caused for example by AGN feedback or externally-induced changes in the bar-driven inflow rate, and not by variations in the depletion time. (4) We study the trajectories of newly born stars in our simulations. We find several examples that have age and 3D velocity compatible with those of the Arches and Quintuplet clusters. Our simulations suggest that these prominent clusters originated near the collision sites where the bar-driven inflow accretes onto the CMZ, at symmetrical locations with respect to the Galactic centre, and that they have already decoupled from the gas in which they were born.

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Section: What Drives the Time Variability Of The Sfr In The Cmz?mentioning

confidence: 77%

Simulations of the Milky Way’s Central Molecular Zone – II. Star formation

Sormani

Treß

Glover

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…Moreover, reproducing the KDL orbit would require that a sequence of clouds are launched with exactly the same initial conditions from the same point in space during a time interval of 5 Myr, which is unlikely to happen given the stochastic nature of the perturbations. Armillotta et al (2020) also report that they are unable to reproduce a stream with the characteristics of the KDL orbit in their simulations. At present, it remains to be shown that excursions compatible with the KDL orbit can occur in a self-consistent simulation of gas flow in a barred potential.…”

Section: Orbits Versus Open Orbit: a False Dichotomy?mentioning

confidence: 99%

“…Molinari et al 2011;Immer et al 2012Immer et al , 2016Jones et al 2012;Ginsburg et al 2016;Henshaw et al 2016;Kauffmann et al 2017a, b;Krieger et al 2017;Longmore et al 2017;Mills et al 2018;Mangilli et al 2019;Oka et al 2019) and theoretical (e.g. Kruijssen, Dale & Longmore 2015;Krumholz & Kruijssen 2015;Sormani, Binney & Magorrian 2015a, c;Krumholz, Kruijssen & Crocker 2017;Ridley et al 2017;Sormani et al 2018Sormani et al , 2019Armillotta et al 2019;Dale, Kruijssen & Longmore 2019;Kruijssen et al 2019a;Armillotta, Krumholz & Di Teodoro 2020;Li, Shen & Schive 2020) sides. Despite these advancements, many important open questions remain.…”

Section: Introductionmentioning

confidence: 99%

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

Treß

Sormani

Glover

et al. 2020

Monthly Notices of the Royal Astronomical Society

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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 ∼ 5 kpc. 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. 2011. (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 $1\rm \, M_\odot \, yr^{-1}$, consistent with observational determinations. (4) Supernova feedback can drive an inflow from the CMZ inwards towards the circumnuclear disc of the order of $\sim 0.03\, \rm M_\odot \, yr^{-1}$. (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 (R ≲ 30 pc) to the Galactic centre, but are also connected to the larger-scale streams at R ≳ 100 pc.

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“…Together with the rest of the CMZ clouds, the Brick is subjected to strong shear (𝑉/𝑅 ∼ 1.7 Myr −1 ; Kruĳssen et al 2014; Krumholz lar clusters (Ginsburg & Kruĳssen 2018). One explanation for the presently low SFR in the region is the idea that the CMZ undergoes bursts of star formation, followed by quiescent phases (Kruĳssen et al 2014;Krumholz et al 2017;Armillotta et al 2020;Sormani et al 2020;Tress et al 2020). Longmore et al (2013b) and Barnes et al (2019Barnes et al ( , 2020 reported an increase of star formation activity as a function of orbital position angle among the subset of CMZ clouds known as the 'dust ridge' (which includes the Brick).…”

Section: Introductionmentioning

confidence: 99%

“…Some authors have performed simulations that follow the gas flow towards the galactic centre and connect kiloparsec scales to the inner few hundred parsecs (e.g. Sormani et al 2015;Armillotta et al 2019Armillotta et al , 2020Tress et al 2020;Sormani et al 2020). These simulations allow us to study the formation and large-scale properties of molecular clouds in the CMZ.…”

Section: Introductionmentioning

confidence: 99%

The complex multi-scale structure in simulated and observed emission maps of the proto-cluster cloud G0.253+0.016 (`the Brick')

Petkova¹,

Kruijssen²,

Kluge³

et al. 2021

Preprint

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The Central Molecular Zone (CMZ; the central ∼ 500 pc of the Milky Way) hosts molecular clouds in an extreme environment of strong shear, high gas pressure and density, and complex chemistry. G0.253+0.016, also known as 'the Brick', is the densest, most compact and quiescent of these clouds. High-resolution observations with the Atacama Large Millimeter/submillimeter Array (ALMA) have revealed its complex, hierarchical structure. In this paper we compare the properties of recent hydrodynamical simulations of the Brick to those of the ALMA observations. To facilitate the comparison, we post-process the simulation and create synthetic ALMA maps of molecular line emission from eight molecules. We correlate the line emission maps to each other and to the mass column density, and find that HNCO is the best mass tracer of the eight emission lines. Additionally, we characterise the spatial structure of the observed and simulated cloud using the density probability distribution function (PDF), spatial power spectrum, fractal dimension, and moments of inertia. While we find good agreement between the observed and simulated data in terms of power spectra and fractal dimensions, there are key differences in terms of the density PDFs and moments of inertia, which we attribute to the omission of magnetic fields in the simulations. Models that include the external gravitational potential generated by the stars in the CMZ better reproduce the observed structure, highlighting that cloud structure in the CMZ results from the complex interplay between internal physics (turbulence, self-gravity, magnetic fields) and the impact of the extreme environment.

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The life cycle of the Central Molecular Zone – II. Distribution of atomic and molecular gas tracers

Cited by 28 publications

References 94 publications

Simulations of the Milky Way’s Central Molecular Zone – II. Star formation

Simulations of the Milky Way’s Central Molecular Zone – II. Star formation

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

The complex multi-scale structure in simulated and observed emission maps of the proto-cluster cloud G0.253+0.016 (`the Brick')

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