Radio Continuum Observations of the Galactic Center: Photoevaporative Proplyd-like Objects near Sgr A*

Abstract

We present radio images within 30$''$ of Sgr A* based on recent VLA observations at 34 GHz with 7.8 microJy sensitivity and resolution $\sim88\times46$ milliarcseconds (mas). We report 44 partially resolved compact sources clustered in two regions in the E arm of ionized gas that orbits Sgr A*. These sources have size scales ranging between ~50 and 200 mas (400 to 1600 AUs), and a bow-shock appearance facing the direction of Sgr A*. Unlike the bow-shock sources previously identified in the near-IR but associated with massive stars, these 34 GHz sources do not appear to have near-IR counterparts at 3.8 $\mu$m. We interpret these sources as a candidate population of photoevaporative protoplanetary disks (proplyds) that are associated with newly formed low mass stars with mass loss rates ~10^{-7} - 10^{-6} solar mass per year and are located at the edge of a molecular cloud outlined by ionized gas. The disks are externally illuminated by strong Lyman continuum radiation from the ~100 OB and WR massive stars distributed within 10'' of Sgr A*. The presence of proplyds implies current in-situ star formation activity near Sgr A* and opens a window for the first time to study low mass star, planetary and brown dwarf formations near a supermassive black hole.