‘The Brick’ is not a<i>brick</i>: a comprehensive study of the structure and dynamics of the central molecular zone cloud G0.253+0.016

Henshaw, Jonathan D.; Ginsburg, Adam; Haworth, Thomas J.; Longmore, S.; Kruijssen, J. M. Diederik; Mills, Elisabeth A. C.; Sokolov, Vlas; Walker, Daniel; Barnes, Ashley; Contreras, Y.; Bally, John; Battersby, Cara; Beuther, H.; Butterfield, Natalie; Dale, James E.; Henning, Th.; Jackson, James M.; Kauffmann, Jens; Pillai, T.; Ragan, S. E.; Riener, M.; Zhang, Qizhou

doi:10.1093/mnras/stz471

Cited by 90 publications

(121 citation statements)

References 132 publications

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“…65 While single dish observations depict G0.253+0.016 as a single, coherent, and centrally-condensed molecular cloud, 66 more recent work suggests that G0.253+0.016 is dynamically complex and hierarchicallystructured. 11 Observations and data…”

Section: Ngc 4321mentioning

confidence: 99%

“…We focus our analysis on one of G0.253+0.016's dominant substructures, extracted using ACORNS. 11 The distribution of optically-thin 11…”

Section: Cmz Gmcmentioning

confidence: 99%

“…5 Although dense star-forming gas likely emerges from a combination of instabilities, 6,7 convergent flows, 8 and turbulence, 9 establishing the precise origin is challenging because it requires quantifying gas motion over many orders of magnitude in spatial scale. Here we measure [10][11][12] the motion of molecular gas in the Milky Way and in nearby galaxy NGC 4321, assembling observations that span an unprecedented spatial dynamic range (10 −1 −10 3 pc). We detect ubiquitous velocity fluctuations across all spatial scales and galactic environments.…”

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confidence: 99%

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Ubiquitous velocity fluctuations throughout the molecular interstellar medium

et al. 2020

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The density structure of the interstellar medium (ISM) determines where stars form and release energy, momentum, and heavy elements, driving galaxy evolution. [1][2][3][4] Density variations are seeded and amplified by gas motion, but the exact nature of this motion is unknown across spatial scale and galactic environment. 5 Although dense star-forming gas likely emerges from a combination of instabilities, 6, 7 convergent flows, 8 and turbulence, 9 establishing the precise origin is challenging because it requires quantifying gas motion over many orders of magnitude in spatial scale. Here we measure [10][11][12] the motion of molecular gas in the Milky Way and in nearby galaxy NGC 4321, assembling observations that span an unprecedented spatial dynamic range (10 −1 −10 3 pc). We detect ubiquitous velocity fluctuations across all spatial scales and galactic environments. Statistical analysis of these fluctuations indicates how star-forming gas is assembled. We discover oscillatory gas flows with wavelengths ranging from 0.3−400 pc. These flows are coupled to regularly-spaced density enhancements that likely form via gravitational instabilities. 13,14 We also identify stochastic and scale-free velocity and density fluctuations, consistent with the structure generated in turbulent flows. 9 Our results demonstrate that ISM structure cannot be considered in isolation. Instead, its formation and evolution is controlled by nested, interdependent flows of matter covering many orders of magnitude in spatial scale.We use observations that trace molecular gas in a variety of galactic environments and span a wide range of spatial scales. We measure the position-position-velocity (p-p-v) structure of the molecular ISM from 0.1 pc scales, relevant for individual star-forming cores, up to the scales of individual giant molecular clouds (GMCs), now accessible in nearby galaxies using facilities such as the Atacama Large Millimeter/submillimeter Array (ALMA). On large (from 100 pc to >1000 pc) scales, we analyse observations of nearby galaxy NGC 4321 from the Physics at High Angular resolution in Nearby GalaxieS (PHANGS-ALMA) survey. At intermediate (from 1 pc to 100 pc) scales, we target both the Galactic disc and the Central Molecular Zone (CMZ, i.e. the central 500 pc) of the Milky Way with data from the Galactic Ring Survey 15 and the Mopra CMZ survey, 16 respectively. On small scales (from 0.1 pc to around 10 pc) we include observations of two dense molecular clouds, G035.39-00.33 17 in the Galactic disc and G0.253+0.016 11 in the CMZ.We extract the kinematics of the gas using spectral decomposition, modelling each spectrum as a set of individual Gaussian emission features. [10][11][12] Spectral decomposition is advantageous because it yields a description of all prominent emission features observed in spectroscopic data. We visualise the results using the peak intensities and velocity centroids of the modelled emission features (Figure 1). This method facilitates the detection of small fluctuations in velocity, which can o...

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Section: Ngc 4321mentioning

confidence: 99%

“…We focus our analysis on one of G0.253+0.016's dominant substructures, extracted using ACORNS. 11 The distribution of optically-thin 11…”

Section: Cmz Gmcmentioning

confidence: 99%

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confidence: 99%

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Ubiquitous velocity fluctuations throughout the molecular interstellar medium

et al. 2020

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“…Heyer et al 2009;Miville-Deschênes et al 2017) and advocate a scaling relation that also takes the surface density into account. Moreover, especially in the inner part of the Galaxy, linewidths can be systematically higher than predicted by the size-linewidth relation, indicating that σ v is at least partly set by Galactic environment (Shetty et al 2012;Henshaw et al 2016Henshaw et al , 2019Rice et al 2016). We want to emphasise here that we do not use the size-linewidth relation to make conclusive decisions about the distance to a gas emission peak, but only use it as additional prior KDA information for sources with v LSR < 20 km s −1 .…”

Section: Prior For the Fitted Linewidthmentioning

confidence: 99%

Autonomous Gaussian decomposition of the Galactic Ring Survey

Riener

Kainulainen

Henshaw

et al. 2020

A&A

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Knowledge about the distribution of CO emission in the Milky Way is essential to understanding the impact of the Galactic environment on the formation and evolution of structures in the interstellar medium. However, our current insight as to the fraction of CO in the spiral arm and interarm regions is still limited by large uncertainties in assumed rotation curve models or distance determination techniques. In this work we use the Bayesian approach from Reid et al. (2016, ApJ, 823, 77; 2019, ApJ, 885, 131), which is based on our most precise knowledge at present about the structure and kinematics of the Milky Way, to obtain the current best assessment of the Galactic distribution of 13CO from the Galactic Ring Survey. We performed two different distance estimates that either included (Run A) or excluded (Run B) a model for Galactic features, such as spiral arms or spurs. We also included a prior for the solution of the kinematic distance ambiguity that was determined from a compilation of literature distances and an assumed size-linewidth relationship. Even though the two distance runs show strong differences due to the prior for Galactic features for Run A and larger uncertainties due to kinematic distances in Run B, the majority of their distance results are consistent with each other within the uncertainties. We find that the fraction of 13CO emission associated with spiral arm features ranges from 76 to 84% between the two distance runs. The vertical distribution of the gas is concentrated around the Galactic midplane, showing full-width at half-maximum values of ~75 pc. We do not find any significant difference between gas emission properties associated with spiral arm and interarm features. In particular, the distribution of velocity dispersion values of gas emission in spurs and spiral arms is very similar. We detect a trend of higher velocity dispersion values with increasing heliocentric distance, which we, however, attribute to beam averaging effects caused by differences in spatial resolution. We argue that the true distribution of the gas emission is likely more similar to a combination of the two distance results discussed, and we highlight the importance of using complementary distance estimations to safeguard against the pitfalls of any single approach. We conclude that the methodology presented in this work is a promising way to determine distances to gas emission features in Galactic plane surveys.

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“…Some galaxy centers host nuclear starbursts (e.g., NGC 253; Leroy et al 2018), whereas the Milky Way's central region, known as the Central Molecular Zone (CMZ) appears to be underproducing stars relative to its dense gas content, with surveys finding an SFR 10-100 times lower than that predicted by contemporary theory (e.g., Immer et al 2012;Longmore et al 2013). This deficiency has motivated many studies of the star-forming properties of molecular clouds in this extreme environment (Rathborne et al 2014;Ginsburg et al 2018;Walker et al 2018;Barnes et al 2019;Henshaw et al 2019).…”

Section: Introductionmentioning

confidence: 99%

Fiery Cores: Bursty and Smooth Star Formation Distributions across Galaxy Centers in Cosmological Zoom-in Simulations

Orr

Hatchfield

Battersby

et al. 2021

ApJL

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We present an analysis of the R  1.5 kpc core regions of seven simulated Milky Way-mass galaxies, from the FIRE-2 (Feedback in Realistic Environments) cosmological zoom-in simulation suite, for a finely sampled period (Δt = 2.2 Myr) of 22 Myr at z ≈ 0, and compare them with star formation rate (SFR) and gas surface density observations of the Milky Way's Central Molecular Zone (CMZ). Despite not being tuned to reproduce the detailed structure of the CMZ, we find that four of these galaxies are consistent with CMZ observations at some point during this 22 Myr period. The galaxies presented here are not homogeneous in their central structures, roughly dividing into two morphological classes; (a) several of the galaxies have very asymmetric gas and SFR distributions, with intense (compact) starbursts occurring over a period of roughly 10 Myr, and structures on highly eccentric orbits through the CMZ, whereas (b) others have smoother gas and SFR distributions, with only slowly varying SFRs over the period analyzed. In class (a) centers, the orbital motion of gas and star-forming complexes across small apertures (R  150 pc, analogously |l| < 1°in the CMZ observations) contributes as much to tracers of star formation/dense gas appearing in those apertures, as the internal evolution of those structures does. These asymmetric/bursty galactic centers can simultaneously match CMZ gas and SFR observations, demonstrating that time-varying star formation can explain the CMZ's low star formation efficiency.

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‘The Brick’ is not abrick: a comprehensive study of the structure and dynamics of the central molecular zone cloud G0.253+0.016

Cited by 90 publications

References 132 publications

Ubiquitous velocity fluctuations throughout the molecular interstellar medium

Ubiquitous velocity fluctuations throughout the molecular interstellar medium

Autonomous Gaussian decomposition of the Galactic Ring Survey

Fiery Cores: Bursty and Smooth Star Formation Distributions across Galaxy Centers in Cosmological Zoom-in Simulations

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