The Fermi Bubbles: Giant, Multi-Billion-Year-Old Reservoirs of Galactic Center Cosmic Rays

Abstract

Recently evidence has emerged for enormous features in the gamma-ray sky observed by the Fermi-LAT instrument: bilateral `bubbles' of emission centered on the core of the Galaxy and extending to around 10 kpc above and below the Galactic plane. These structures are coincident with a non-thermal microwave `haze' found in WMAP data and an extended region of X-ray emission detected by ROSAT. The bubbles' gamma-ray emission is characterised by a hard and relatively uniform spectrum, relatively uniform intensity, and an overall luminosity ~4 x 10^37 erg/s, around one order of magnitude larger than their microwave luminosity while more than order of magnitude less than their X-ray luminosity. Here we show that the bubbles are naturally explained as due to a population of relic cosmic ray protons and heavier ions injected by processes associated with extremely long timescale (>~8 Gyr) and high areal density star-formation in the Galactic center.

Accepted for publication in Phys.Rev.Lett. 4 pages, 2 figures, brief textual revisions, conclusions unchanged

References in corpus (8)

• Giant Gamma-ray Bubbles from Fermi-LAT: AGN Activity or Bipolar Galactic Wind?
• Draping of Cluster Magnetic Fields over Bullets and Bubbles -- Morphology and Dynamic Effects
• Discrete sources as the origin of the Galactic X-ray ridge emission
• Extended Anomalous Foreground Emission in the WMAP 3-Year Data
• The Starburst Contribution to the Extra-Galactic Gamma-Ray Background
• Does the Milky Way Produce a Nuclear Galactic Wind?
• Cosmic ray confinement in fossil cluster bubbles
• Fermi Gamma-ray Space Telescope: High-Energy Results from the First Year

Cited by in corpus (65)

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• The Galactic Centre Chimney
• Wild at Heart:-The Particle Astrophysics of the Galactic Centre
• Probing the Fermi Bubbles in Ultraviolet Absorption: A Spectroscopic Signature of the Milky Way's Biconical Nuclear Outflow
• A Galactic Halo Origin of the Neutrinos Detected by IceCube
• Nuclear Outflow of the Milky Way: Studying the Kinematics and Spatial Extent of the Northern Fermi Bubble
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• The Return of the Templates: Revisiting the Galactic Center Excess with Multi-Messenger Observations
• Modelling of the Spectral Energy Distribution of Fornax A: Leptonic and Hadronic Production of High Energy Emission from the Radio Lobes
• Dark Matter Indirect Signatures
• The Spatially Uniform Spectrum of the Fermi Bubbles: the Leptonic AGN Jet Scenario
• Simulating the Fermi Bubbles as Forward Shocks Driven by AGN Jets
• Gamma-ray Lines in the Fermi Data: is it a Bubble?
• Gamma rays from the Galactic Centre region: a review
• Clues to the origin of Fermi Bubbles from OVIII/OVII line ratio
• Detection Potential of the KM3NeT Detector for High-Energy Neutrinos from the Fermi Bubbles
• Magnetic substructure in the northern Fermi Bubble revealed by polarized WMAP emission
• Giant cosmic ray halos around M31 and the Milky Way
• Quasar-driven outflows account for the missing extragalactic gamma-ray background
• Multi-wavelength Emission from the Fermi Bubble III. Stochastic (Fermi) Re-Acceleration of Relativistic Electrons Emitted by SNRs
• Particle Diffusion and Acceleration in Magnetorotational Instability Turbulence
• Multi-wavelength Emission from the Fermi Bubble II. Secondary Electrons and the Hadronic Model of the Bubble
• Multi-wavelength Emission from the Fermi Bubble I. Stochastic acceleration from Background Plasma
• A Supernova-driven, Magnetically-collimated Outflow as the Origin of the Galactic Center Radio Bubbles
• Cosmic Rays in a Galactic Breeze
• Years Delayed Gamma-ray and Radio Afterglows Originated from TDE Wind-Torus Interactions
• Search for Blazar Flux-Correlated TeV Neutrinos in IceCube 40-String Data
• Can observations of 511 keV line from the M31 galaxy shed light on the AGN jet composition?
• Positron Annihilation in the Nuclear Outflows of the Milky Way
• The population of Galactic centre filaments III: candidate radio and stellar sources
• Unveiling the Fermi Bubbles origin with MeV photon telescopes
• Fermi Bubbles and Bubble-like emission from the Galactic Plane
• Identifying Galactic Sources of High-Energy Neutrinos
• Emission from hadronic and leptonic processes in galactic jet-driven bubbles
• Metal Enrichment in the Fermi Bubbles as a Probe of Their Origin
• Probing the Halo Gas Distribution in the Inner Galaxy with Fermi Bubble Observations
• QUIJOTE scientific results -- VI. The Haze as seen by QUIJOTE
• Galactic Centre as an efficient source of cosmic rays
• Imaging the positron annihilation line with 20 years of INTEGRAL/SPI observations
• Galactic breeze origin for the Fermi bubbles emission
• The AGN Jet Model of the Fermi Bubbles
• Not gone with the Wind: Survival of High-Velocity Molecular Clouds in the Galactic center
• Search for TeV emission from the Fermi Bubbles at low Galactic latitudes with H.E.S.S. inner Galaxy survey observations
• Microquasar remnants as hidden PeVatrons
• Fermi bubbles as a source of cosmic rays above 10^{15} eV
• A possible origin of gamma rays from the Fermi Bubbles
• X-rays from a Central "Exhaust Vent" of the Galactic Center Chimney
• Hot spots in the neutrino flux created by cosmic rays from Cygnus and Vela?
• Observations of the Fermi bubbles and the Galactic center excess with the DArk Matter Particle Explorer
• Possible counterpart signal of the Fermi bubbles at the cosmic-ray positrons
• Evidence for powerful winds and the associated reverse shock as the origin of the Fermi bubbles
• Multi-wavelength emission from leptonic processes in ageing galaxy bubbles
• Supermassive black holes and their surroundings: MeV signatures
• Fermi-bubble bulk and edge analysis reveals dust, cooling breaks, and cosmic-ray diffusion, facilitating a self-consistent model
• Detection of Gamma-ray Halos around Nearby Late-type Galaxies
• On the high-energy protons regular acceleration in the Fermi Bubbles
• Diffuse continuum emission and large extended sources at MeV energies
• High Energy Emission from the Galactic Center
• The role of magnetic fields in shaping $\gamma$-ray emission from the Fermi bubbles
• Measuring the smearing of the Galactic 511 keV signal: positron propagation or supernova kicks?
• Diffuse Hot Plasma in the Interstellar Medium and Galactic Outflows
• Cosmic Ray (Stochastic) Acceleration from a Background Plasma