A Census of Early Phase High-Mass Star Formation in the Central Molecular Zone

Abstract

We present new observations of C-band continuum emission and masers to assess high-mass ($>$8 $M_{\odot }$) star formation at early evolutionary phases in the inner 200 pc of the Central Molecular Zone (CMZ) of the Galaxy. The continuum observation is complete to free-free emission from stars above 10-11 $M_{\odot }$ in 91% of the covered area. We identify 104 compact sources in the continuum emission, among which five are confirmed ultracompact H II regions, 12 are candidates of ultra-compact H II regions, and the remaining 87 sources are mostly massive stars in clusters, field stars, evolved stars, pulsars, extragalactic sources, or of unknown nature that is to be investigated. We detect class II CH${}_3$OH masers at 23 positions, among which six are new detections. We confirm six known H${}_2$CO masers in two high-mass star forming regions, and detect two new H${}_2$CO masers toward the Sgr C cloud, making it the ninth region in the Galaxy that contains masers of this type. In spite of these detections, we find that current high-mass star formation in the inner CMZ is only taking place in seven isolated clouds. The results suggest that star formation at early evolutionary phases in the CMZ is about 10 times less efficient than expected by the dense gas star formation relation, which is in line with previous studies that focus on more evolved phases of star formation. This means that if there will be any impending, next burst of star formation in the CMZ, it has not yet begun.

arXiv comment26 pages, 7 pages, 6 tables. ApJ accepted. The continuum images are publicly available at https://doi.org/10.5281/zenodo.3361115 . A pdf file with finer image resolutions is available at https://xinglunju.github.io/files/HMSFinCMZ.pdf

References in corpus (91)

• Astropy: A Community Python Package for Astronomy
• Gaia Data Release 2. Summary of the contents and survey properties
• On the variation of the Initial Mass Function
• Detection of the gravitational redshift in the orbit of the star S2 near the Galactic centre massive black hole
• Clouds, filaments and protostars: the Herschel Hi-GAL Milky Way
• On the Star Formation Rates in Molecular Clouds
• A Catalog of Extended Green Objects (EGOs) in the GLIMPSE Survey: A new sample of massive young stellar object outflow candidates
• The WISE Catalog of Galactic HII Regions
• Variations in the Galactic star formation rate and density thresholds for star formation
• A Minimum Column Density of 1 g cm^-2 for Massive Star Formation
• What controls star formation in the central 500 pc of the Galaxy?
• The 6-GHz methanol multibeam maser catalogue I: Galactic Centre region, longitudes 345 to 6
• How Many Infrared Dark Clouds can form Massive Stars and Clusters?
• The dynamical evolution of molecular clouds near the Galactic Centre - I. Orbital structure and evolutionary timeline
• Dense gas in the Galactic central molecular zone is warm and heated by turbulence
• Star Formation in the Central 400 pc of the Milky Way: Evidence for a Population of Massive YSOs
• The link between turbulence, magnetic fields, filaments, and star formation in the Central Molecular Zone cloud G0.253+0.016
• Methanol masers : Reliable tracers of the early stages of high-mass star formation
• A Catalog of X-ray Point Sources from Two Megaseconds of Chandra Observations of the Galactic Center
• Star formation rates and efficiencies in the Galactic Centre
• The H_2O southern Galactic Plane Survey (HOPS): I. Techniques and H_2O maser data
• Characterizing Precursors to Stellar Clusters with Herschel
• A $\lambda$20cm Survey of the Galactic Center Region I: Detection of Numerous Linear Filaments
• The thermal state of molecular clouds in the Galactic Center: evidence for non-photon-driven heating
• The RMS Survey: Critical Tests of Accretion Models for the Formation of Massive Stars
• Dynamics of Ionized Gas at the Galactic Center: VLA Observations of the 3D Velocity Field and Location of the Ionized Streams in Sagittarius A West
• Confirmation of the exclusive association between 6.7-GHz methanol masers and high-mass star formation regions
• Candidate super star cluster progenitor gas clouds possibly triggered by close passage to Sgr A*
• A Dynamical Model for the Formation of Gas Rings and Episodic Starbursts Near Galactic Centres
• The Galactic Center Molecular Cloud Survey. I. A Steep Linewidth-Size Relation & Suppression of Star Formation
• HASH: the Hong Kong/AAO/Strasbourg H-alpha planetary nebula database
• BLOBCAT: Software to Catalogue Flood-Filled Blobs in Radio Images of Total Intensity and Linear Polarization
• A high-sensitivity 6.7 GHz methanol maser survey toward H2O sources
• A cluster in the making: ALMA reveals the initial conditions for high-mass cluster formation
• A Dynamical Model for Gas Flows, Star Formation, and Nuclear Winds in Galactic Centres
• The Galactic Center Cloud G0.253+0.016: A Massive Dense Cloud with low Star Formation Potential
• 'The Brick' is not a brick: A comprehensive study of the structure and dynamics of the Central Molecular Zone cloud G0.253+0.016
• Distributed star formation throughout the Galactic Center cloud Sgr B2
• Precise Positions of Methanol Masers
• A Model for the Onset of Self-gravitation and Star Formation in Molecular Gas Governed by Galactic Forces: I. Cloud-scale Gas Motions
• HST Paschen-alpha Survey of the Galactic Center: Data Reduction and Products
• The Survey of Water and Ammonia in the Galactic Center (SWAG): Molecular Cloud Evolution in the Central Molecular Zone
• Near-infrared counterparts to Chandra X-ray sources toward the Galactic Center. II. Discovery of Wolf-Rayet stars and O supergiants
• A Chandra Catalog of X-ray Sources in the Central 150 pc of the Galaxy
• The dynamical evolution of molecular clouds near the Galactic Centre - II. Spatial structure and kinematics of simulated clouds
• HST/NICMOS Paschen-alpha Survey of the Galactic Center: Overview
• Isolated Wolf-Rayet Stars and O Supergiants in the Galactic Center Region Identified via Paschen-alpha Excess
• Recent star formation in the inner Galactic Bulge seen by ISOGAL II -- The Central Molecular Zone
• A VLA H92alpha Study of the Arched Filament Complex Near the Galactic Center
• Tracing the Conversion of Gas into Stars in Young Massive Cluster Progenitors
• Massive Young Stellar Objects in the Galactic Center. I. Spectroscopic Identification from Spitzer/IRS Observations
• A New Catalog of Radio Compact HII Regions in the Milky Way
• A multi-wavelength view of the Galactic center dust ridge reveals little star formation
• Stellar Winds and Embedded Star Formation in the Galactic Center Quintuplet and Arches Clusters: Multifrequency Radio Observations
• Abundant Methanol Masers but no New Evidence for Star Formation in GCM0.253+0.016
• An Ultra-deep Chandra Catalog of X-ray Point Sources in the Galactic Center Star Cluster
• Star Formation Rates of Massive Molecular Clouds in the Central Molecular Zone
• Star formation in a high-pressure environment: An SMA view of the Galactic centre dust ridge
• Spectral imaging of the Central Molecular Zone in multiple 7-mm molecular lines
• The Galactic Center Molecular Cloud Survey. II. A Lack of Dense Gas & Cloud Evolution along Galactic Center Orbits
• Main-sequence stars masquerading as Young Stellar Objects in the central molecular zone
• A High-Resolution Survey of HI Absorption toward the Central 200 pc of the Galactic Center
• Continuum sources from the THOR survey between 1 and 2 GHz
• Early stage massive star formation near the Galactic Center: Sgr C
• Deciphering the ionized gas content in the massive star forming complex G75.78+0.34
• The Molecular Gas Environment in the 20 km s${}^{-1}$ Cloud in the Central Molecular Zone
• A New Perspective of the Radio Bright Zone at The Galactic Center: Feedback from Nuclear Activities
• Young massive star cluster formation in the Galactic Centre is driven by global gravitational collapse of high-mass molecular clouds
• Radio continuum emission in the northern Galactic plane: Sources and spectral indices from the THOR survey
• The dynamical evolution of molecular clouds near the Galactic Centre -- III. Tidally--induced star formation in protocluster clouds
• High-mass star-forming cloud G0.38+0.04 in the Galactic Center Dust Ridge contains H2CO and SiO masers
• On the physical mechanisms governing the cloud lifecycle in the Central Molecular Zone of the Milky Way
• The eMERGE Survey I: Very Large Array 5.5 GHz observations of the GOODS-North Field
• Evidence of Short Timescale Flux Density Variations of UC HII regions in Sgr B2 Main and North
• Properties of the Compact HII Region Complex G-0.02-0.07
• Star formation in the massive "starless" infrared dark cloud G0.253$+$0.016
• Massive Star Formation of the Sgr A East HII Regions Near the Galactic Center
• Radio Detection of A Candidate Neutron Star Associated with Galactic Center Supernova Remnant Sagittarius A East
• ALMA View of the Galactic Center Mini-spiral: Ionized Gas Flows around Sagittarius A*
• Hard X-rays from Ultra-Compact HII Regions in W49A
• Galactic Center Mini-spiral by ALMA - Possible Origin of the Central Cluster
• M0.20-0.033: An Expanding Molecular Shell in the Galactic Center Radio Arc
• A Large--Scale Spectroscopic Survey of Methanol and OH Line Emission from the Galactic Center: Observations and Data
• A 6.7 GHz methanol maser survey of the central molecular zone
• Star Formation Sites toward the Galactic Center Region: The Correlation of CH3OH Masers, H2O Masers, and Near-IR Green Sources
• Methanol Maser Emission from Galactic Center Sources with Excess 4.5 μm Emission
• The Unusual Galactic Center Radio Source N3
• IRTF/TEXES Observations of the HII Regions H1 and H2 in the Galactic Centre
• Pumping of the 4.8 GHz H${}_{\text{2}}$CO masers and its implications for the periodic masers in G37.55+0.20
• An Infrared Study of the Dust Properties and Geometry of the Arched Filaments HII Region with SOFIA/FORCAST
• Sagittarius B2 Main: A Cluster of Ultra-Compact HII Regions and Massive Protostellar Cores

Cited by in corpus (27)

• Cloud-cloud collision as drivers of the chemical complexity in Galactic Centre molecular clouds
• CMZoom: Survey Overview and First Data Release
• ALMA Observations of Massive Clouds in the Central Molecular Zone: Jeans Fragmentation and Cluster Formation
• 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
• CMZoom II: Catalog of Compact Submillimeter Dust Continuum Sources in the Milky Way's Central Molecular Zone
• A massive Keplerian protostellar disk with flyby-induced spirals in the Central Molecular Zone
• The centres of M83 and the Milky Way: opposite extremes of a common star formation cycle
• A global view on star formation: The GLOSTAR Galactic plane survey IV. Radio continuum detections of young stellar objects in the Galactic Centre region
• A global view on star formation: The GLOSTAR Galactic plane survey VIII. Formaldehyde absorption in Cygnus~X
• The Milky Way Atlas for Linear Filaments
• A wind-blown bubble in the Central Molecular Zone cloud G0.253+0.016
• Reexploring Molecular Complexity with ALMA: Insights into chemical differentiation from the molecular composition of hot cores in Sgr B2(N2)
• The physical and chemical structure of Sagittarius B2, VIII. Full molecular line survey of hot cores
• The initial conditions for young massive cluster formation in the Galactic Centre: convergence of large-scale gas flows
• Dual-band Unified Exploration of Three CMZ Clouds (DUET). Cloud-wide census of continuum sources showing low spectral indices
• The JWST-NIRCam View of Sagittarius C. II. Evidence for Magnetically Dominated HII Regions in the CMZ
• Hot Molecular Core Candidates in the Galactic Center 50 km/s Molecular Cloud
• Revisiting the formaldehyde masers
• Discovery of non-metastable ammonia masers in Sagittarius B2
• ALMA observations of massive clouds in the central molecular zone: slim filaments tracing parsec-scale shocks
• Chandra X-ray Measurement of Heavy Element Abundances of Wolf-Rayet Stars in the Galactic Center
• SOFIA/HAWC+ Far-Infrared Polarimetric Large Area CMZ Exploration Survey. V. The Magnetic Field Strength and Morphology in the Sagittarius C Complex
• Discovery of widespread non-metastable ammonia masers in the Milky Way
• Mass Segregation in the CMZoom Survey
• 6.7 GHz CH3OH absorption towards the N3 Galactic Center point-source
• The Dense Gas Mass Fraction and the Relationship to Star Formation in M51