ALMA uncovers highly filamentary structure towards the Sgr E region

Abstract

We report on the discovery of linear filaments observed in CO(1-0) emission for a $\sim 2^{\prime }$ field of view toward the Sgr E star forming region centered at (l,b)=(358.720${}^{\circ }$, 0.011${}^{\circ }$). The Sgr E region is thought to be at the turbulent intersection of the ''far dust lane'' associated with the Galactic bar and the Central Molecular Zone (CMZ). This region is subject to strong accelerations which are generally thought to inhibit star formation, yet Sgr E contains a large number of HII regions. We present ${}^{12}$CO(1-0), ${}^{13}$CO(1-0), and C${}^{18}$O(1-0) spectral line observations from ALMA and provide measurements of the physical and kinematic properties for two of the brightest filaments. These filaments have widths (FWHM) of $\sim 0.1$ pc and are oriented nearly parallel to the Galactic plane, with angles from the Galactic plane of $\sim 2^{\circ }$. The filaments are elongated, with lower limit aspect ratios of $\sim$5:1. For both filaments we detect two distinct velocity components that are separated by about 15 km s${}^{-1}$. In the C${}^{18}$O spectral line data with $\sim$0.09 pc spatial resolution, we find that these velocity components have relatively narrow ($\sim$1-2 km s${}^{-1}$) FWHM linewidths when compared to other sources towards the Galactic center. The properties of these filaments suggest that the gas in the Sgr E complex is being ''stretched'' as it is rapidly accelerated by the gravitational field of the Galactic bar while falling towards the CMZ, a result that could provide insight into the extreme environment surrounding this region and the large-scale processes which fuel this environment.

arXiv comment20 pages, 17 figures, accepted for publication in ApJ

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• The Population of the Galactic Center Filaments: Position Angle Distribution Reveal a Degree-scale Collimated Outflow from Sgr A* along the Galactic Plane
• WISDOM Project -- XV. Giant Molecular Clouds in the Central Region of the Barred Spiral Galaxy NGC 5806
• 3-D CMZ IV: Distinguishing Near vs. Far Distances in the Galactic Center Using Spitzer and Herschel
• Revealing Gas Inflows towards the Galactic Central Molecular Zone
• Star Formation in Extreme Environments: A 200 pc High Velocity Gas Stream in the Galactic Centre
• A 260 pc resolution ALMA map of HCN(1-0) in the galaxy NGC 4321
• Gas Transfer Between the Inner 3-kpc Disk and the Galactic Central Molecular Zone
• ALMA observations of massive clouds in the central molecular zone: slim filaments tracing parsec-scale shocks