Signatures of Young Star Formation Activity Within Two Parsecs of Sgr A*

Abstract

We present radio and infrared observations indicating on-going star formation activity inside the $\sim 2-5$ pc circumnuclear ring at the Galactic center. Collectively these measurements suggest a continued disk-based mode of on-going star formation has taken place near Sgr A* over the last few million years. First, VLA observations with spatial resolution 2.17$"\times 0.81"$ reveal 13 water masers, several of which have multiple velocity components. The presence of interstellar water masers suggests gas densities that are sufficient for self-gravity to overcome the tidal shear of the 4$\times 10^6$ \msol\, black hole. Second, SED modeling of stellar sources indicate massive YSO candidates interior to the molecular ring, supporting in-situ star formation near Sgr A* and appear to show a distribution similar to that of the counter-rotating disks of $\sim$100 OB stars orbiting Sgr A*. Some YSO candidates (e.g., IRS~5) have bow shock structures suggesting that they have have gaseous disks that are phototoevaporated and photoionized by the strong radiation field. Third, we detect clumps of SiO (2-1) and (5-4) line emission in the ring based on CARMA and SMA observations. The FWHM and luminosity of the SiO emission is consistent with shocked protostellar outflows. Fourth, two linear ionized features with an extent of $\sim 0.8$ pc show blue and redshifted velocities between $+50$ and $-40$ \kms, suggesting protostellar jet driven outflows with mass loss rates of $\sim 5\times 10^{-5}$ solar mass yr${}^{-1}$. Finally, we present the imprint of radio dark clouds at 44 GHz, representing a reservoir of molecular gas that feeds star formation activity close to Sgr A*.

38 pages, 10 figures, ApJ (in press)

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Cited by in corpus (15)

• Simulations of the Milky Way's central molecular zone -- II. Star formation
• The Circumnuclear Disk Revealed by ALMA. I. Dense Clouds and Tides in the Galactic Center
• ALMA Detection of Bipolar Outflows: Evidence for Low Mass Star Formation within 1pc of Sgr A*
• Galactic Center Mini-spiral by ALMA - Possible Origin of the Central Cluster
• Effect of an isotropic outflow from the Galactic centre on the bow-shock evolution along the orbit
• Hot Molecular Gas in the Circumnuclear Disk
• ALMA and VLA observations of emission from the environment of Sgr A*
• Accurate OH maser positions II. the Galactic Center region
• Sgr A* and its Environment: Low Mass Star Formation, the Origin of X-ray Gas and Collimated Outflow
• Electron-positron pair production near the Galactic Centre and the 511 keV emission line
• Constraining dark matter by the 511 keV line
• Stability of planetary systems within the S-star cluster: the Solar system analogues
• The Fate of Binary Stars Hosting Planets upon Interaction with Sgr A* Black hole
• Star Formation Close to Sgr A* and Beyond the Nuclear Cluster
• Parsec-scale SiO emission in the Galactic Center