Star Formation Rates of Massive Molecular Clouds in the Central Molecular Zone

Abstract

We investigate star formation at very early evolutionary phases in five massive clouds in the inner 500 pc of the Galaxy, the Central Molecular Zone. Using interferometer observations of H${}_2$O masers and ultra-compact H II regions, we find evidence of ongoing star formation embedded in cores of 0.2 pc scales and $\gtrsim$10${}^5$ cm${}^{-3}$ densities. Among the five clouds, Sgr C possesses a high (9%) fraction of gas mass in gravitationally bound and/or protostellar cores, and follows the dense ($\gtrsim$10${}^4$ cm${}^{-3}$) gas star formation relation that is extrapolated from nearby clouds. The other four clouds have less than 1% of their cloud masses in gravitationally bound and/or protostellar cores, and star formation rates 10 times lower than predicted by the dense gas star formation relation. At the spatial scale of these cores, the star formation efficiency is comparable to that in Galactic disk sources. We suggest that the overall inactive star formation in these Central Molecular Zone clouds could be because there is much less gas confined in gravitationally bound cores, which may be a result of the strong turbulence in this region and/or the very early evolutionary stage of the clouds when collapse has only recently started.

ApJ accepted. SMA and VLA data are made public at https://doi.org/10.5281/zenodo.1436909 and analysis scripts are available at https://github.com/xinglunju/CMZclouds. 32 pages including 4 appendices, 20 figures, 7 tables

References in corpus (20)

• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• Structural Analysis of Molecular Clouds: Dendrograms
• Multi-Scale CLEAN deconvolution of radio synthesis images
• The Critical Density and the Effective Excitation Density of Commonly Observed Molecular Dense Gas Tracers
• The dynamical evolution of molecular clouds near the Galactic Centre - I. Orbital structure and evolutionary timeline
• Intrinsically Red Sources observed by Spitzer in the Galactic Mid-Plane
• Spatial distribution of interstellar gas in the innermost 3 kpc of our Galaxy
• Star Formation in the Central 400 pc of the Milky Way: Evidence for a Population of Massive YSOs
• Magnetic Fields in High-Mass Infrared Dark Clouds
• The link between turbulence, magnetic fields, filaments, and star formation in the Central Molecular Zone cloud G0.253+0.016
• Turbulence sets the initial conditions for star formation in high-pressure environments
• The Survey of Water and Ammonia in the Galactic Center (SWAG): Molecular Cloud Evolution in the Central Molecular Zone
• Galactocentric variation of the gas-to-dust ratio and its relation with metallicity
• Accurate water maser positions from HOPS
• Water maser variability over 20 years in a large sample of star-forming regions: the complete database
• The W43-MM1 mini-starburst ridge, a test for star formation efficiency models
• The dynamics and star-forming potential of the massive Galactic centre cloud G0.253+0.016
• Abundant Methanol Masers but no New Evidence for Star Formation in GCM0.253+0.016
• Star formation in a high-pressure environment: An SMA view of the Galactic centre dust ridge
• A Large--Scale Spectroscopic Survey of Methanol and OH Line Emission from the Galactic Center: Observations and Data

Cited by in corpus (25)

• The 1.28 GHz MeerKAT Galactic Center Mosaic
• 'The Brick' is not a brick: A comprehensive study of the structure and dynamics of the Central Molecular Zone cloud G0.253+0.016
• Cloud-cloud collision as drivers of the chemical complexity in Galactic Centre molecular clouds
• Ultra-diffuse galaxies without dark matter
• Dark Matter Deficient Galaxies Produced Via High-velocity Galaxy Collisions In High-resolution Numerical Simulations
• CMZoom: Survey Overview and First Data Release
• ALMA Observations of Massive Clouds in the Central Molecular Zone: Jeans Fragmentation and Cluster Formation
• Young massive star cluster formation in the Galactic Centre is driven by global gravitational collapse of high-mass molecular clouds
• Star formation in 'the Brick': ALMA reveals an active proto-cluster in the Galactic centre cloud G0.253+0.016
• ALMA Observations of Massive Clouds in the Central Molecular Zone: Ubiquitous Protostellar Outflows
• A massive Keplerian protostellar disk with flyby-induced spirals in the Central Molecular Zone
• SOFIA/HAWC+ Far-Infrared Polarimetric Large-Area CMZ Exploration (FIREPLACE) Survey III: Full Survey Data Set
• A global view on star formation: The GLOSTAR Galactic plane survey IV. Radio continuum detections of young stellar objects in the Galactic Centre region
• Effects of Varying Mass Inflows on Star Formation in Nuclear Rings of Barred Galaxies
• A wind-blown bubble in the Central Molecular Zone cloud G0.253+0.016
• Virial Clumps in Central Molecular Zone Clouds
• Kinematics of Galactic Centre clouds shaped by shear-seeded solenoidal turbulence
• The initial conditions for young massive cluster formation in the Galactic Centre: convergence of large-scale gas flows
• Gravitationally Bound Gas Determines Star Formation in the Galaxy
• CMZoom III: Spectral Line Data Release
• Dual-band Unified Exploration of Three CMZ Clouds (DUET). Cloud-wide census of continuum sources showing low spectral indices
• Hot Molecular Core Candidates in the Galactic Center 50 km/s Molecular Cloud
• Turbulence and its connection to episodic accretion in binary YSOs
• ALMA observations of massive clouds in the central molecular zone: slim filaments tracing parsec-scale shocks
• Molecular Clouds at the Edge of the Galaxy II. Physical properties and scaling relations