The Interaction of the Fermi Bubbles with the Milky Way's Hot Gas Halo

Abstract

The Fermi bubbles are two lobes filled with non-thermal particles that emit gamma rays, extend $\approx$10 kpc vertically from the Galactic center, and formed from either nuclear star formation or accretion activity on Sgr A*. Simulations predict a range of shock strengths as the bubbles expand into the surrounding hot gas halo distribution ($T_{halo}\approx 2\times 10^6$ K), but with significant uncertainties in the energetics, age, and thermal gas structure. The bubbles should contain thermal gas with temperatures between $10^6$ and $10^8$ K, with potential X-ray signatures. In this work, we constrain the bubbles' thermal gas structure by modeling the OVII and OVIII emission line strengths from archival XMM-Newton and Suzaku data. Our emission model includes a hot thermal volume-filled bubble component cospatial with the gamma-ray region, and a shell of compressed material. We find that a bubble/shell model with $n\approx 1\times 10^{-3}$ cm${}^{-3}$ and with log($T$) $\approx$ 6.60-6.70 is consistent with the observed line intensities. In the framework of a continuous Galactic outflow, we infer a bubble expansion rate, age, and energy injection rate of $490_{-77}^{+230}$ km s${}^{-1}$, $4.3_{-1.4}^{+0.8}$ Myr, and $2.3_{-0.9}^{+5.1}\times 10^{42}$ erg s${}^{-1}$. These estimates are consistent with the bubbles forming from a Sgr A* accretion event rather than from nuclear star formation.

Accepted for publication in ApJ - 23 pages, 11 figures, 3 tables

References in corpus (31)

• Heating Hot Atmospheres with Active Galactic Nuclei
• An Observational Determination of the Bolometric Quasar Luminosity Function
• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• The XMM-Newton Serendipitous Survey. V. The Second XMM-Newton Serendipitous Source Catalogue
• The Spectrum and Morphology of the Fermi Bubbles
• An Unambiguous Detection of Faraday Rotation in Sagittarius A*
• Turbulent Structure of a Stratified Supernova-Driven Interstellar Medium
• Fueling Low-Level AGN Activity Through the Stochastic Accretion of Cold Gas
• Constraining the Milky Way's Hot Gas Halo with OVII and OVII Emission Lines
• Numerical Simulation of Hot Accretion Flows (III): Revisiting wind properties using trajectory approach
• Extended Anomalous Foreground Emission in the WMAP 3-Year Data
• Star Formation in the Central 400 pc of the Milky Way: Evidence for a Population of Massive YSOs
• Do Hot Haloes Around Galaxies Contain the Missing Baryons?
• Vertical structure of a supernova-driven turbulent magnetized ISM
• A New Model For The Loop-I (The North Polar Spur) Region
• X-Ray Absorption from the Milky Way Halo and the Local Group
• Probing the Fermi Bubbles in Ultraviolet Absorption: A Spectroscopic Signature of the Milky Way's Biconical Nuclear Outflow
• Charge-Transfer induced EUV and Soft X-ray emissions in the Heliosphere
• Fermi Bubbles Inflated by Winds Launched from the Hot Accretion Flow in Sgr A*
• OVII and OVIII line emission in the diffuse soft X-ray background: heliospheric and galactic contributions
• The origin of the 'local' 1/4 keV X-ray flux in both charge exchange and a hot bubble
• The Trouble with the Local Bubble
• Identifying XMM-Newton observations affected by solar wind charge exchange - Part I
• X-ray and UV spectroscopy of Galactic diffuse hot gas along the LMC X--3 sight line
• Xmm-Newton Observations of the Diffuse X-ray Background
• The North Polar Spur and Aquila Rift
• A Hadronic-Leptonic Model for the Fermi Bubbles: Cosmic-Rays in the Galactic Halo and Radio Emission
• Multi-wavelength Emission from the Fermi Bubble III. Stochastic (Fermi) Re-Acceleration of Relativistic Electrons Emitted by SNRs
• Suzaku X-ray Observations of the Fermi Bubbles: Northernmost Cap and Southeast Claw Discovered with MAXI-SSC
• Determining The Galactic Halo's Emission Measure from UV and X-ray Observations
• Metal Enrichment in the Fermi Bubbles as a Probe of Their Origin

Cited by in corpus (24)

• Detection of large-scale X-ray bubbles in the Milky Way halo
• Mass inflow rate into the Central Molecular Zone: observational determination and evidence of episodic accretion
• Fermi and eRosita bubbles as relics of the past activity of the Galactic black hole
• The large-scale ionization cones in the Galaxy
• Cold gas in the Milky Way's nuclear wind
• Circumgalactic Oxygen Absorption and Feedback
• The Spatially Uniform Spectrum of the Fermi Bubbles: the Leptonic AGN Jet Scenario
• Simulating the Fermi Bubbles as Forward Shocks Driven by AGN Jets
• The Properties of the Galactic Hot Gaseous Halo from X-ray Emission
• Observation of Acceleration of HI Clouds Within the Fermi Bubbles
• Mapping Outflowing Gas in the Fermi Bubbles: a UV Absorption Survey of the Galactic Nuclear Wind
• Clues to the origin of Fermi Bubbles from OVIII/OVII line ratio
• Revealing the Ionization Properties of the Magellanic Stream using Optical Emission
• Kinematics of the Magellanic Stream and Implications for its Ionization
• Interaction of the Galactic-Centre Super Bubbles with the Gaseous Disc
• Origin of Galactic Spurs: New Insight from Radio/X-ray All-sky Maps
• Discovery of High-Velocity H$\alpha$ Emission in the Direction of the Fermi Bubble
• Diagnostics of Gaseous Halo of the Milky Way by a Shock Wave from the Galactic Centre
• The Solar-Cycle Temporal Variation of the Solar Wind Charge Exchange X-ray Lines
• Diverse metallicities of Fermi bubble clouds indicate dual origins in the disk and halo
• Revealing Gas Inflows towards the Galactic Central Molecular Zone
• The time-dependent Rayleigh-Taylor instability in interstellar shells and supershells, including the eROSITA bubbles
• Discovery of non-equilibrium ionization plasma associated with the North Polar Spur and Loop I
• CO Emission Delineating the Interface between the Milky Way Nuclear Wind Cavity and the Gaseous Disk