Enrico Di Teodoro (ANU)

Enrico Di Teodoro Colloquium: Atomic Hydrogen Clouds Tracing the Galactic Nuclear Outflow

Marsfield Lecture Theatre

Abstract

I present the results of a new deep survey of neutral hydrogen (HI) above and below the Galactic Center with the Green Bank Telescope, extending up to Galactic latitude | b | < 10 degrees. The survey reveals the existence of a population of anomalous high-velocity clouds extending up to heights of 1.5 kpc from the Galactic Plane and showing no signature of Galactic rotation. These clouds have local standard of rest velocities | VLSR | < 350 km/s, typical sizes of few tens pc and HI masses of a few hundreds solar masses. I model the cloud kinematics in terms of an outflow expanding from the Galactic Center and find the population consistent with being material moving with radial velocities 300 km/s < Vw < 400 km/s inside a bi-cone with opening angle a > 140 degrees. These clouds likely represent the cold gas component entrained in the nuclear wind driven by our Galaxy.