Observation of Acceleration of HI Clouds Within the Fermi Bubbles

Abstract

The ~200 HI clouds observed to be entrained in the Fermi Bubble wind show a trend of increasing maximum |VLSR| with Galactic latitude. We analyze previous observations and present new data from the Green Bank Telescope that rule out systematic effects as the source of this phenomenon. Instead, it is likely evidence for acceleration of the clouds. The data suggest that clouds in the lower 2 kpc of the Fermi Bubbles, within the Bubble boundaries established from X-ray studies, have an outflow velocity that rises from ~150 - 200 km/s close to the Galactic Center and reaches ~330 km/s at a distance of 2.5 - 3.5 kpc. These parameters are also consistent with the kinematics of UV absorption lines from highly ionized species observed against two targets behind the Fermi Bubbles at $b=-6.6^{\circ }$, and $b=+11.2^{\circ }$. The implied neutral cloud lifetime is 4 - 10 Myr.

Accepted for publication in the Astrophysical Journal

References in corpus (11)

• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• Extended Anomalous Foreground Emission in the WMAP 3-Year Data
• Magnetized Gas Clouds can Survive Acceleration by a Hot Wind
• Giant Magnetized Outflows from the Centre of the Milky Way
• The Launching of Cold Clouds by Galaxy Outflows I: Hydrodynamic Interactions with Radiative Cooling
• Hydrodynamical Coupling of Mass and Momentum in Multiphase Galactic Winds
• Probing the Fermi Bubbles in Ultraviolet Absorption: A Spectroscopic Signature of the Milky Way's Biconical Nuclear Outflow
• Nuclear Outflow of the Milky Way: Studying the Kinematics and Spatial Extent of the Northern Fermi Bubble
• The Interaction of the Fermi Bubbles with the Milky Way's Hot Gas Halo
• Does the Milky Way Produce a Nuclear Galactic Wind?
• The large-scale ionization cones in the Galaxy

Cited by in corpus (22)

• Cold gas in the Milky Way's nuclear wind
• The Survival of Multiphase Dusty Clouds in Hot Winds
• The Galactic center chimneys: The base of the multiphase outflow of the Milky Way
• Shock-multicloud interactions in galactic outflows -- I. Cloud layers with log-normal density distributions
• Mapping Outflowing Gas in the Fermi Bubbles: a UV Absorption Survey of the Galactic Nuclear Wind
• Mass, Morphing, Metallicities: The Evolution of Infalling High Velocity Clouds
• The turbulent gas structure in the centers of NGC253 and the Milky Way
• Molecular Gas within the Milky Way's Nuclear Wind
• Direct observations of the atomic-molecular phase transition in the Milky Way's nuclear wind
• Discovery of High-Velocity H$\alpha$ Emission in the Direction of the Fermi Bubble
• Diverse metallicities of Fermi bubble clouds indicate dual origins in the disk and halo
• Caught in the Act: A Metal-Rich High-Velocity Cloud in the Inner Galaxy
• Revealing Gas Inflows towards the Galactic Central Molecular Zone
• CO Emission Delineating the Interface between the Milky Way Nuclear Wind Cavity and the Gaseous Disk
• Galactic breeze origin for the Fermi bubbles emission
• One-kpc Expanding Cylinder of HI-Gas around the Galactic Center
• Not gone with the Wind: Survival of High-Velocity Molecular Clouds in the Galactic center
• X-rays from a Central "Exhaust Vent" of the Galactic Center Chimney
• A New High-latitude H I Cloud Complex Entrained in the Northern Fermi Bubble
• The role of magnetic fields in shaping $\gamma$-ray emission from the Fermi bubbles
• Modelling the non-equilibrium chemistry of the Milky Way's cold nuclear wind
• How is Cold Gas Loaded into Galactic Nuclear Outflows?