Evidence for a jet and outflow from Sgr A*: a continuum and spectral line study

Abstract

We study the environment of Sgr A* using spectral and continuum observations with the ALMA and VLA. Our analysis of sub-arcsecond H30alpha, H39alpha, H52alpha and H56alpha line emission towards Sgr A* confirm the recently published broad peak ~500 km/s~spectrum toward Sgr~A*. We also detect emission at more extreme radial velocities peaking near -2500 and 4000 km/s, within 0.2''. We then present broad band radio continuum images at multiple frequencies on scales from arcseconds to arcminutes. A number of elongated continuum structures lie parallel to the Galactic plane, extending from ~0.4'' to 10'. We note a nonthermal elongated structure on an arcminute scale emanating from Sgr A* at low frequencies between 1 and 1.4 GHz where thermal emission from the mini-spiral is depressed by optical depth effects. The position angle of this elongated structure and the sense of motion of ionized features with respect to Sgr A* suggest a symmetric, collimated jet emerging from Sgr A* with an opening angle of ~30deg and a position angle of ~60deg punching through the medium before accelerating a significant fraction of the orbiting ionized gas to high velocities. The jet with estimated mass flow rate ~1.4x10^{-5} solar mass/yr emerges perpendicular to the equatorial plane of the accretion flow near the event horizon of Sgr A* and runs along the Galactic plane. To explain a number of east-west features near Sgr A*, we also consider the possibility of an outflow component with a wider-angle launched from the accretion flow at larger radii.

26 pages, 14 figures, MNRAS, in press

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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
• First observed interaction of the circumstellar envelope of an S-star with the environment of Sgr A*
• Upper Limit on Brackett-gamma Emission from the Immediate Accretion Flow onto the Galactic Black Hole
• Mid-Infrared studies of dusty sources in the Galactic Center
• Nonthermal filaments from the tidal destruction of clouds in the Galactic center
• Polarized signatures of adiabatically expanding hotspots in Sgr A*'s accretion flow
• The formation and stability of a cold disc made out of stellar winds in the Galactic Centre
• Deep learning inference with the Event Horizon Telescope III. Zingularity results from the 2017 observations and predictions for future array expansions
• Missing bright red giants in the Galactic center: A fingerprint of its once active state?