A Multiwavelength Study of the Sgr B Region: Contiguous Cloud-Cloud Collisions Triggering Widespread Star Formation Events?

Abstract

The Sgr\,B region, including Sgr\,B1 and Sgr\,B2, is one of the most active star-forming regions in the Galaxy. Hasegawa et al. (1994) originally proposed that Sgr\,B2 was formed by a cloud-cloud collision (CCC) between two clouds with velocities of $\sim$45 km~s${}^{-1}$ and $\sim$75 km~s${}^{-1}$. However, some recent observational studies conflict with this scenario. We have re-analyzed this region, by using recent, fully sampled, dense-gas data and by employing a recently developed CCC identification methodology, with which we have successfully identified more than 50 CCCs and compared them at various wavelengths. We found two velocity components that are widely spread across this region and that show clear signatures of a CCC, each with a mass of $\sim$10${}^6$ $M_{\odot }$. Based on these observational results, we suggest an alternative scenario, in which contiguous collisions between two velocity features with a relative velocity of $\sim$20 km~s${}^{-1}$ created both Sgr\,B1 and Sgr\,B2. The physical parameters, such as the column density and the relative velocity of the colliding clouds, satisfy a relation that has been found to apply to the most massive Galactic CCCs, meaning that the triggering of high-mass star formation in the Galaxy and starbursts in external galaxies can be understood as being due to the same physical CCC process.

arXiv comment18 pages, 10 figures

References in corpus (54)

• The Infrared Array Camera (IRAC) for the Spitzer Space Telescope
• Herschel Space Observatory - An ESA facility for far-infrared and submillimetre astronomy
• The Herschel-SPIRE instrument and its in-flight performance
• Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)
• Mapping the Three-Dimensional Density of the Galactic Bulge with VVV Red Clump Stars
• Dynamical modelling of the Galactic bulge and bar: the Milky Way's bar pattern speed, stellar, and dark matter mass distribution
• A 100-parsec elliptical and twisted ring of cold and dense molecular clouds revealed by Herschel around the Galactic Center
• 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
• Molecular gas kinematics within the central 250 pc of the Milky Way
• Formation of Massive Molecular Cloud Cores by Cloud-cloud Collision
• FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope (FUGIN) I: Project Overview and Initial Results
• Star formation rates and efficiencies in the Galactic Centre
• Spectral imaging of the Central Molecular Zone in multiple 3-mm molecular lines
• Do cloud-cloud collisions trigger high-mass star formation? I. Small cloud collisions
• A lower limit of 50 microgauss for the magnetic field near the Galactic Centre
• A $\lambda$20cm Survey of the Galactic Center Region I: Detection of Numerous Linear Filaments
• SiO emission from the Galactic Center Molecular Clouds
• The pattern speed of the Milky Way bar from transverse velocities
• Candidate super star cluster progenitor gas clouds possibly triggered by close passage to Sgr A*
• Isolating signatures of major cloud-cloud collisions using position-velocity diagrams
• Cloud-cloud collisions and triggered star formation
• Revealing the physical properties of molecular gas in Orion with a large scale survey in J=2-1 lines of 12CO, 13CO and C18O
• The Bolocam Galactic Plane Survey IV: 1.1 and 0.35 mm Dust Continuum Emission in the Galactic Center Region
• Gas flow in barred potentials - III. Effects of varying the Quadrupole
• A new look at the molecular gas in M42 and M43; possible evidence for cloud-cloud collision which triggered formation of the OB stars in the Orion Nebula Cluster
• Distributed star formation throughout the Galactic Center cloud Sgr B2
• Formation of the Young Massive Cluster R136 triggered by Tidally-driven Colliding HI Flows
• Simulations of the Milky Way's central molecular zone -- II. Star formation
• The dynamical evolution of molecular clouds near the Galactic Centre - II. Spatial structure and kinematics of simulated clouds
• A theoretical explanation for the Central Molecular Zone asymmetry
• The geometry of the gas surrounding the Central Molecular Zone: on the origin of localised molecular clouds with extreme velocity dispersions
• Cloud-cloud collisions in the common foot point of molecular loops 1 and 2 in the Galactic Center
• The Mopra Southern Galactic Plane CO Survey - Data Release 3
• RCW 36 in the Vela Molecular Ridge: Evidence for a high-mass star cluster formation triggered by Cloud-Cloud Collision
• FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope (FUGIN) 2: Possible evidence for formation of NGC~6618 cluster in M17 by cloud-cloud collision
• ISO-LWS observations of C+ and O lines in absorption toward SgrB2
• High-mass star formation possibly triggered by cloud-cloud collision in the HII region RCW 34
• FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope (FUGIN) : Molecular clouds toward W33 ; possible evidence for a cloud-cloud collision triggering O star formation
• Formation of the young compact cluster GM 24 triggered by a cloud-cloud collision
• Water Masers in W49 North and Sagittarius B2
• Molecular clouds toward three Spitzer bubbles S116, S117 and S118: Evidence for the cloud-cloud collision which formed the three \HII \ regions and a 10-pc scale molecular cavity
• High-mass star formation in Orion B triggered by cloud-cloud collision: Merging molecular clouds in NGC 2024
• Large-scale CO J=1-0 observations of the giant molecular cloud associated with the infrared ring N35 with the Nobeyama 45-m telescope
• Structure and kinematics of shocked gas in Sgr B2: further evidence of a cloud-cloud collision from SiO emission maps
• Stochastic Noncircular Motion and Outflows Driven by Magnetic Activity in the Galactic Bulge Region
• The formation of a Spitzer bubble RCW79 triggered by cloud-cloud collision
• Anisotropic Turbulence in Position-Position-Velocity Space: Probing Three-Dimensional Magnetic Fields
• Discovery of possible molecular counterparts to the infrared Double Helix Nebula in the Galactic center
• Triggering the formation of the supergiant H II region NGC 604 in M33
• Detailed CO ($J$ = 1--0, 2--1 and 3--2) observations toward an H{\sc ii} region RCW~32 in the Vela Molecular Ridge
• SOFIA FIFI-LS Observations of Sgr B1: Ionization Structure and Sources of Excitation
• High-Resolution Observations of Molecular Lines toward the Hot Core G28.20-0.04N
• Massive star formation in the Carina nebula complex and Gum 31 -- II. a cloud-cloud collision in Gum 31

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• Ammonia mapping observations of the Galactic infrared bubble N49: Three NH${}_3$ clumps along the molecular filament
• Parabolic-like Trend in SiO Ratios throughout the Central Molecular Zone: Possible Signature of a Past Nuclear Activity in the Galactic Center