ALMA View of the Galactic Center Mini-spiral: Ionized Gas Flows around Sagittarius A*

Abstract

We have performed the observation of the "Galactic Center Mini-spiral(GCMS)" in H42alpha recombination line as a part of the first large-scale mosaic observation in the Sagittarius A complex using Atacama Millimeter/sub-millimeter Array (ALMA). We revealed the kinematics of the ionized gas streamers of the GCMS. We found that the ionized gas streamers of the Northern Arm(NA) and Eastern Arm(EA) in their outer regions somewhat deviate from the Keplerian orbits which were derived previously from the trajectories in the inner regions. In addition, we found that the streamer corresponding to the Bar of the GCMS has a Keplerian orbit with an eccentricity of e~0.8, which is independent from the Keplerian orbits of the other streamers of the GCMS. We estimated the LTE electron temperature and electron density in the ionized gas streamers. We confirmed the previously claimed tendency that the electron temperatures increase toward Sgr A*. We found that the electron density in the NA and EA also increases with approaching Sgr A* without the lateral expansion of the gas streamers. This suggests that there is some external pressure around the GCMS. The ambient ionized gas may cause the confinement and/or the perturbation for the orbits. There is a good positional correlation between the protostar candidates detected by JVLA at 34 GHz and the ionized gas streamer, Northeastern Arm, newly found by our H42alpha recombination line observation. This suggests that the candidates had formed in the streamer and they were brought to near Sgr A* as the streamer falls.

35 pages, 12 figures, Accepted for publication in ApJ

References in corpus (4)

• The Two Young Star Disks in the Central Parsec of the Galaxy: Properties, Dynamics and Formation
• Dynamics of Ionized Gas at the Galactic Center: VLA Observations of the 3D Velocity Field and Location of the Ionized Streams in Sagittarius A West
• Radio Continuum Observations of the Galactic Center: Photoevaporative Proplyd-like Objects near Sgr A*
• Galactic Center Mini-spiral by ALMA - Possible Origin of the Central Cluster

Cited by in corpus (19)

• The 1.28 GHz MeerKAT Galactic Center Mosaic
• A Census of Early Phase High-Mass Star Formation in the Central Molecular Zone
• ALMA View of the Circum-nuclear Disk of the Galactic Center; Tidally-disrupted Molecular Clouds falling to the Galactic Center
• The Second Galactic Center Black Hole?; A Possible Detection of Ionized Gas Orbiting around an IMBH embedded in the Galactic Center IRS13E complex
• A Magnetic Field Connecting the Galactic Center Circumnuclear Disk with Streamers and Mini-spiral -Implications from 850 $\mu$m Polarization Data
• Colliding Winds in and around the Stellar Group IRS 13E at the Galactic Center
• Near- and mid-infrared observations in the inner tenth of a parsec of the Galactic center -- Detection of proper motion of a filament very close to Sgr~A*
• Tracing the Milky Way's Vestigial Nuclear Jet
• Rotating Ionized Gas Ring around the Galactic Center IRS13E3
• ALMA Detection of Extreme Blue-Shifted Ionized Gas Within 0.2 pc of Sgr A* from -480 to -300 km/s
• The Inner 2 pc of Sagittarius A*: Simulations of the Circumnuclear Disk and Multiphase Gas Accretion in the Galactic Center
• Dusty plasma in active galactic nuclei
• X3: a high-mass Young Stellar Object close to the supermassive black hole Sgr~A*
• How far actually is the Galactic Center IRS 13E3 from Sagittarius A${}^{\ast }$?
• The Evaporating Massive Embedded Stellar Cluster IRS 13 Close to Sgr A*. II. Kinematic structure
• Sub-millimeter Detection of a Galactic Center Cool Star IRS 7 by ALMA
• ALMA Astrometry of the Objects within 0.5 pc of Sagittarius A${}^{\ast }$
• MOLsphere and pulsations of the Galactic Center's red supergiant GCIRS 7 from VLTI/GRAVITY
• The Discovery of an Active Wind from the Milky Way's Black Hole