The Molecular Gas Environment in the 20 km s${}^{-1}$ Cloud in the Central Molecular Zone

Abstract

We recently reported a population of protostellar candidates in the 20 km s${}^{-1}$ cloud in the Central Molecular Zone of the Milky Way, traced by H${}_2$O masers in gravitationally bound dense cores. In this paper, we report high-angular-resolution ($\sim$3'') molecular line studies of the environment of star formation in this cloud. Maps of various molecular line transitions as well as the continuum at 1.3 mm are obtained using the Submillimeter Array. Five NH${}_3$ inversion lines and the 1.3 cm continuum are observed with the Karl G. Jansky Very Large Array. The interferometric observations are complemented with single-dish data. We find that the CH${}_3$OH, SO, and HNCO lines, which are usually shock tracers, are better correlated spatially with the compact dust emission from dense cores among the detected lines. These lines also show enhancement in intensities with respect to SiO intensities toward the compact dust emission, suggesting the presence of slow shocks or hot cores in these regions. We find gas temperatures of $\gtrsim$100 K at 0.1-pc scales based on RADEX modelling of the H${}_2$CO and NH${}_3$ lines. Although no strong correlations between temperatures and linewidths/H${}_2$O maser luminosities are found, in high-angular-resolution maps we notice several candidate shock heated regions offset from any dense cores, as well as signatures of localized heating by protostars in several dense cores. Our findings suggest that at 0.1-pc scales in this cloud star formation and strong turbulence may together affect the chemistry and temperature of the molecular gas.

22 pages, 10 figures, 2 tables, 1 appendix. ApJ accepted

References in corpus (18)

• Formation of methyl formate and other organic species in the warm-up phase of hot molecular cores
• MAMBO Mapping of Spitzer c2d Small Clouds and Cores
• 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
• The largest oxigen bearing organic molecule repository
• 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
• A cluster in the making: ALMA reveals the initial conditions for high-mass cluster formation
• Turbulence sets the initial conditions for star formation in high-pressure environments
• VLA observations of ammonia in high-mass star formation regions
• G0.253+0.016: A centrally condensed, high-mass protocluster
• The dynamics and star-forming potential of the massive Galactic centre cloud G0.253+0.016
• A multi-wavelength view of the Galactic center dust ridge reveals little star formation
• Abundant Methanol Masers but no New Evidence for Star Formation in GCM0.253+0.016
• Physical conditions of molecular gas in the Circinus galaxy: Multi-J CO and CI 1-0 observations
• Coupling the dynamics and the molecular chemistry in the Galactic center
• Molecular shock tracers in NGC 1068: SiO and HNCO
• Temperature structures in Galactic Center clouds - Direct evidence for gas heating via turbulence

Cited by in corpus (25)

• Measurement of the cosmic ray helium energy spectrum from 70 GeV to 80 TeV with the DAMPE space mission
• Simulations of the Milky Way's central molecular zone -- I. Gas dynamics
• Distributed star formation throughout the Galactic Center cloud Sgr B2
• The dynamical evolution of molecular clouds near the Galactic Centre - II. Spatial structure and kinematics of simulated clouds
• The Dense Gas Fraction in Galactic Center Clouds
• Star Formation Rates of Massive Molecular Clouds in the Central Molecular Zone
• Solar and nuclear physics uncertainties in cosmic-ray propagation
• ALMA Observations of Massive Clouds in the Central Molecular Zone: Jeans Fragmentation and Cluster Formation
• A Census of Early Phase High-Mass Star Formation in the Central Molecular Zone
• ATLASGAL-selected massive clumps in the inner Galaxy: VI. Kinetic temperature and spatial density measured with formaldehyde
• H2O Southern Galactic Plane Survey (HOPS): Paper III - Properties of Dense Molecular Gas across the Inner Milky Way
• Young massive star cluster formation in the Galactic Centre is driven by global gravitational collapse of high-mass molecular clouds
• The ALMA Survey of 70 $\mu$m Dark High-mass Clumps in Early Stages (ASHES). IV. Star formation signatures in G023.477
• ALMA Observations of Massive Clouds in the Central Molecular Zone: Ubiquitous Protostellar Outflows
• Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde. III. The Orion Molecular Cloud 1
• Chemistry of the High-Mass Protostellar Molecular Clump IRAS 16562-3959
• Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde IV. The ALMA view of N113 and N159W in the LMC
• Fragmentation of the High-mass "Starless'' Core G10.21-0.31: a Coherent Evolutionary Picture for Star Formation
• SMA Observations of Extended $\mathrm{CO}(\mathrm{J}=2-1)$ Emission in Interacting Galaxy NGC 3627
• Kinetic temperature of massive star-forming molecular clumps measured with formaldehyde V. The massive filament DR21
• A common origin for the circumnuclear disc and the nearby molecular clouds in the Galactic Centre
• 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
• High-spectral resolution M-band observations of CO Rot-Vib absorption lines towards the Galactic center
• ALMA observations of massive clouds in the central molecular zone: slim filaments tracing parsec-scale shocks