The Nuclear Filaments inside the Circumnuclear Disk in the Central 0.5 pc of the Galactic center

TL;DR

This study uses high-resolution ALMA observations to reveal nuclear filaments within the Galactic Center's circumnuclear disk, showing they are rotating in a nearly face-on orbit and are likely formed by external clouds passing Sgr A*.

Contribution

First homogeneous high-resolution mapping linking molecular streamers in the CND with nuclear filaments, revealing their warped structure and distinct inclinations.

Findings

Nuclear filaments rotate with Keplerian velocities.

Filaments are nearly face-on with ~10-20° inclination.

CND is highly inclined at ~65-80°.

Abstract

We present CS(7-6) line maps toward the central parsec of the Galactic Center (GC), conducted with the Atacama Large Millimeter/submillimeter Array (ALMA). The primary goal is to find and characterize the gas structure in the inner cavity of the circumnuclear disk (CND) in high resolution (1.3"=0.05 pc). Our large field-of-view mosaic maps -- combining interferometric and single-dish data that recover extended emission - provide a first homogeneous look to resolve and link the molecular streamers in the CND with the neutral nuclear filaments newly detected within the central cavity of the CND. We find that the nuclear filaments are rotating with Keplerian velocities in a nearly face-on orbit with an inclination angle of ~10-20 degree (radius <= 0.5 pc). This is in contrast to the CND which is highly inclined at ~65-80 degree (radius ~2-5 pc). Our analysis suggests a highly warped structure from the CND to the nuclear filaments. This result may hint that the nuclear filaments and the CND were created by different external clouds passing by Sgr A*.