The Population of the Galactic Center Filaments: Position Angle Distribution Reveals a Degree-scale Collimated Outflow from Sgr A* along the Galactic Plane

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Yusef-Zadeh_2023_ApJL_949_L31.pdf (3.84 MB)

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https://iopscience.iop.org/article/10.3847/2041-8213/acd54b

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https://doi.org/10.3847/2041-8213/acd54b
 http://hdl.handle.net/11603/28234

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UMBC Center for Space Sciences and Technology (CSST) / Center for Research and Exploration in Space Sciences & Technology II (CRSST II)
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https://orcid.org/0000-0001-8403-8548

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2023-06-02

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journal articles
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Yusef-Zadeh, F., et al. "The Population of the Galactic Center Filaments: Position Angle Distribution Reveals a Degree-scale Collimated Outflow from Sgr A* along the Galactic Plane." The Astrophysical Journal Letters 949, L31 (02 June, 2023). https://doi.org/10.3847/2041-8213/acd54b.

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Abstract

We have examined the distribution of the position angle (PA) of the Galactic center filaments with lengths L > 66" and <66" as well as their length distribution as a function of PA. We find bimodal PA distributions of the filaments, and long and short populations of radio filaments. Our PA study shows the evidence for a distinct population of short filaments with PA close to the Galactic plane. Mainly thermal, short-radio filaments (<66") have PAs concentrated close to the Galactic plane within 60° < PA < 120°. Remarkably, the short filament PAs are radial with respect to the Galactic center at l < 0° and extend in the direction toward Sgr A* . On a smaller scale, the prominent Sgr E H II complex G358.7-0.0 provides a vivid example of the nearly radial distribution of short filaments. The bimodal PA distribution suggests a different origin for two distinct filament populations. We argue that the alignment of the short filament population results from the ram pressure of a degree-scale outflow from Sgr A* that exceeds the internal filament pressure, and aligns them along the Galactic plane. The ram pressure is estimated to be 2 × 10⁶ cm⁻³ K at a distance of 300 pc, requiring biconical mass outflow rate 10⁻⁴ M⊙ yr⁻¹ with an opening angle of ∼40°. This outflow aligns not only the magnetized filaments along the Galactic plane but also accelerates thermal material associated with embedded or partially embedded clouds. This places an estimate of ∼6 Myr as the age of the outflow.