Modeling Bright Gamma-ray and Radio Emission at Fast Cloud Shocks

Abstract

Recent observations by the Large Area Telescope (LAT) onboard the Fermi satellite have revealed bright gamma-ray emission from middle-aged supernova remnants (SNRs) inside our Galaxy. These remnants, which also possess bright non-thermal radio shells, are often found to be interacting directly with surrounding gas clouds. We explore the non-thermal emission mechanism at these dynamically evolved SNRs by constructing a hydrodynamical model. Two scenarios of particle acceleration, either a re-acceleration of Galactic cosmic rays (CRs) or an efficient nonlinear diffusive shock acceleration (NLDSA) of particles injected from downstream, are considered. Using parameters inferred from observations, our models are contrasted with the observed spectra of SNR W44. For the re-acceleration case, we predict a significant enhancement of radio and GeV emission as the SNR undergoes a transition into the radiative phase. If sufficiently strong magnetic turbulence is present in the molecular cloud, the re-acceleration scenario can explain the observed broadband spectral properties. The NLDSA scenario also succeeds in explaining the $\gamma$-ray spectrum but fails to reproduce the radio spectral index. Efficient NLDSA also results in a significant post-shock non-thermal pressure that limits the compression during cooling and prevents the formation of a prominent dense shell. Some other interesting differences between the two models in hydrodynamical behavior and resulting spectral features are illustrated.

arXiv comment13 pages, 5 figures, accepted for publication at The Astrophysical Journal

References in corpus (56)

• Atomic Data for Astrophysics. II. New Analytic Fits for Photoionization Cross Sections of Atoms and Ions
• Detection of the Characteristic Pion-Decay Signature in Supernova Remnants
• Thermal Conduction in Clusters of Galaxies
• Supernova Remnants in Molecular Clouds
• Molecular Cloud Formation in Shock-Compressed Layers
• Fermi-LAT Discovery of Extended Gamma-ray Emission in the Direction of Supernova Remnant W51C
• Toward Understanding the Cosmic-ray Acceleration at Young Supernova Remnants Interacting with Interstellar Clouds: Possible Applications to RX J1713.7-3946
• Observation of Supernova Remnant IC443 with the Fermi Large Area Telescope
• Neutral pion emission from accelerated protons in the supernova remnant W44
• A Physical Relationship Between Electron-Proton Temperature Equilibration and Mach Number in Fast Collisionless Shocks
• Balmer-Dominated Spectra of Nonradiative Shocks in the Cygnus Loop, RCW 86 and Tycho Supernova Remnants
• Fermi LAT Observations of the Supernova Remnant W28 (G6.4-0.1)
• Gamma rays from molecular clouds illuminated by cosmic rays escaping from interacting supernova remnants
• Gamma-ray Emission from Crushed Clouds in Supernova Remnants
• Shocked Molecular Gas in the Supernova Remnants W 28 and W 44: Near-infrared and millimeter-wave observations
• Analytic Solution for Self-regulated Collective Escape of Cosmic Rays from their Acceleration Sites
• Escape-limited Model of Cosmic-ray Acceleration Revisited
• Suzaku Discovery of the Strong Radiative Recombination Continuum of Iron from the Supernova Remnant W49B
• Fermi LAT Observations of Supernova Remnants Interacting with Molecular Clouds
• Direct Evidence for Hadronic Cosmic-Ray Acceleration in the Supernova Renmant IC 443
• Discovery of Strong Radiative Recombination Continua from The Supernova Remnant IC 443 with Suzaku
• ASCA Observations of the Supernova Remnant IC 443: Thermal Structure and Detection of Overionized Plasma
• Electron heat conduction in the solar wind: transition from Spitzer-Härm to the collisionless limit
• Fermi-LAT Discovery of GeV Gamma-ray Emission from the Vicinity of SNR W44
• Non-linear shock acceleration in the presence of seed particles
• Gamma rays from molecular clouds illuminated by accumulated diffusive protons from supernova remnant W28
• Mechanism for spectral break in cosmic ray proton spectrum from Supernova remnant W44
• Molecular Clouds as a Probe of Cosmic-Ray Acceleration in a Supernova Remnant
• A Sino-German 6cm polarization survey of the Galactic plane VII. Small supernova remnants
• Anisotropic CR diffusion and gamma-ray production close to supernova remnants, with an application to W28
• Magnetic field amplification in nonlinear diffusive shock acceleration including resonant and non-resonant cosmic-ray driven instabilities
• The low frequency radio emission and spectrum of the extended SNR W44: new VLA observations at 74 and 324 MHz
• Resolved shock structure of the Balmer-dominated filaments in Tycho's supernova remnant: Cosmic-ray precursor?
• Recombining Plasma and Hard X-ray Filament in the Mixed-Morphology Supernova Remnant W44
• Infrared Spectroscopy of Molecular Supernova Remnants
• A Generalized Model of Nonlinear Diffusive Shock Acceleration Coupled to an Evolving Supernova Remnant
• Detailed Investigation of the Gamma-Ray Emission in the Vicinity of SNR W28 with FERMI-LAT
• Gamma-ray emission of accelerated particles escaping a supernova remnant in a molecular cloud
• The Supernova Remnant W44: confirmations and challenges for cosmic-ray acceleration
• The Role of Diffusive Shock Acceleration on Non-Equilibrium Ionization in Supernova Remnants
• The Heating of Thermal Electrons in Fast Collisionless Shocks: The Integral Role of Cosmic Rays
• Are Models for Core-Collapse Supernova Progenitors Consistent with the Properties of Supernova Remnants?
• Cosmic-Ray Acceleration Efficiency vs Temperature Equilibration: the Case of SNR 0509-67.5
• Cosmic Ray streaming from SNRs and gamma ray emission from nearby molecular clouds
• Metal-Absorption Column Densities in Fast Radiative Shocks
• Evolution of Supernova Remnants Expanding out of the Dense Circumstellar Matter into the Rarefied Interstellar Medium
• Molecular Environment and an X-ray Spectroscopy of Supernova Remnant Kesteven 78
• Constraints on spinning dust towards Galactic targets with the VSA: a tentative detection of excess microwave emission towards 3C396
• An XMM-Newton study of the mixed-morphology supernova remnant W28 (G6.4-0.1)
• The Role of Diffusive Shock Acceleration on Nonequilibrium Ionization in Supernova Remnant Shocks II: Emitted Spectra
• Radiative instabilities in simulations of spherically symmetric supernova blast waves
• Collisionless shocks in partly ionized plasma with cosmic rays: microphysics of non-thermal components
• 3-D Model of Broadband Emission from Supernova Remnants Undergoing Non-linear Diffusive Shock Acceleration
• Gamma-Ray Emission from Supernova Remnant Interaction with Molecular Clumps
• Reverse and Forward Shock X-ray Emission in an Evolutionary Model of Supernova Remnants undergoing Efficient Diffusive Shock Acceleration
• The faint supernova remnant G 34.7-0.4 (W44)

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• Gamma-ray emission from middle-aged supernova remnants interacting with molecular clouds: the challenge for current models
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