Nonthermal THz to TeV Emission from Stellar Wind Shocks in the Galactic Center

Abstract

The central parsec of the Galaxy contains dozens of massive stars with a cumulative mass loss rate of ~ 10^{-3} solar masses per year. Shocks among these stellar winds produce the hot plasma that pervades the central part of the galaxy. We argue that these stellar wind shocks also efficiently accelerate electrons and protons to relativistic energies. The relativistic electrons inverse Compton scatter the ambient ultraviolet and far infrared radiation field, producing high energy gamma-rays with a roughly constant luminosity from \~ GeV to ~ 10 TeV. This can account for the TeV source seen by HESS in the Galactic Center. Our model predicts a GLAST counterpart to the HESS source with a luminosity of ~ 10^{35} ergs/s and cooling break at ~ 4 GeV. Synchrotron radiation from the same relativistic electrons should produce detectable emission at lower energies, with a surface brightness ~ 10^{32} B^2_{-3} ergs/s/arcsec^2 from ~ THz to ~ keV, where B_{-3} is the magnetic field strength in units of mG. The observed level of diffuse thermal X-ray emission in the central parsec requires B < 300 micro-G in our models. Future detection of the diffuse synchrotron background in the central parsec can directly constrain the magnetic field strength, providing an important boundary condition for models of accretion onto Sgr A*.

arXiv commentsubmitted to ApJ Letters

References in corpus (21)

• Generation of Magnetic Fields in the Relativistic Shock of Gamma-Ray-Burst Sources
• Chandra X-ray Spectroscopic Imaging of Sgr A* and the Central Parsec of the Galaxy
• The Stellar Cusp Around the Supermassive Black Hole in the Galactic Center
• Very high energy gamma rays from the direction of Sagittarius A*
• HCN and HCO+ Observations of the Galactic Circumnuclear Disk
• Gamma-Ray Background from Structure Formation in the Intergalactic Medium
• Constraining the Accretion Rate Onto Sagittarius A* Using Linear Polarization
• Detection of TeV gamma-ray Emission from the Shell-Type Supernova Remnant RX J0852.0-4622 with H.E.S.S
• Detection of Sub-TeV Gamma-Rays from the Galactic Center Direction by CANGAROO-II
• Gamma-Rays from Intergalactic Shocks
• A Dynamical Model for Hot Gas in the Galactic Center
• Evidence for a Weak Galactic Center Magnetic Field from Diffuse Low Frequency Nonthermal Radio Emission
• Sgr A* Polarization: No ADAF, Low Accretion Rate, and Non-Thermal Synchrotron Emission
• Hydrodynamical Accretion Onto Sgr A* From Distributed Point Sources
• New Results on the Helium Stars in the Galactic Center Using BEAR Spectro-Imagery
• Three-Dimensional Magnetohydrodynamic Simulations of Spherical Accretion
• Radiatively Inefficient Accretion Flow Models of Sgr A*
• Diffuse X-Rays from the Inner 3 Parsecs of the Galaxy
• TeV Emission from the Galactic Center Black-Hole Plerion
• Discovery of a Radio Supernova Remnant and Non-thermal X-rays Coincident with the TeV Source HESS J1813-178
• A Model of the EGRET Source at the Galactic Center: Inverse Compton Scattering Within Sgr A East and its Halo

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• G359.95-0.04: Pulsar Candidate Near Sgr A*
• Inverse Compton Scenarios for the TeV Gamma-Ray Emission of the Galactic Centre
• Spectral Energy Distribution of the inner accretion flow around Sgr A* -- Clue for a weak outflow in the innermost region
• Simultaneous H.E.S.S. and Chandra observations of Sagittarius A* during an X-ray flare
• The Properties and Fate of the Galactic Center G2 Cloud
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• Magnetohydrodynamic Shocks in Non-Equatorial Plasma Flows around a Black Hole
• ALMA and VLA observations of emission from the environment of Sgr A*
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• Hard X-ray emission in the star-forming region ON2: discovery with XMM-Newton
• Fermi LAT observations of Sagittarius A*: Imaging Analysis
• Probing the Density in the Galactic Center Region: Wind-Blown Bubbles and High-Energy Proton Constraints
• High-(Energy)-Lights -- The Very High Energy Gamma-Ray Sky
• Non-thermal emission from fall-back clouds in the Broad-Line Region of Active Galactic Nuclei