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Title of Journal: Sol Phys

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Abbravation: Solar Physics

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Springer Netherlands

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DOI

10.1002/macp.1964.020760118

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ISSN

1573-093X

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Evidence that Synchrotron Emission from Nonthermal

Authors: Adriana V R Silva G H Share R J Murphy J E R Costa C G Giménez de Castro JP Raulin P Kaufmann
Publish Date: 2007/11/08
Volume: 245, Issue: 2, Pages: 311-326
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Abstract

We investigate the origin of the increasing spectra observed at submillimeter wavelengths detected in the flare on 2 November 2003 starting at 1717 UT This flare classified as an X83 and 2B event was simultaneously detected by RHESSI and the Solar Submillimeter Telescope SST at 212 and 405 GHz Comparison of the time profiles at various wavelengths shows that the submillimeter emission resembles that of the highenergy X rays observed by RHESSI whereas the microwaves observed by the Owens Valley Solar Array OVSA resemble that of ∼50 keV X rays Moreover the centroid position of the submillimeter radiation is seen to originate within the same flaring loops of the ultraviolet and Xray sources Nevertheless the submillimeter spectra are distinct from the usual microwave spectra appearing to be a distinct spectral component with peak frequency in the THz range Three possibilities to explain this increasing radio spectra are discussed 1 gyrosynchrotron radiation from accelerated electrons 2 bremsstrahlung from thermal electrons and 3 gyrosynchrotron emission from the positrons produced by pion or radioactive decay after nuclear interactions The latter possibility is ruled out on the grounds that to explain the submillimeter observations requires 3000 to 2×105 more positrons than what is inferred from Xray and γray observations It is possible to model the emission as thermal however such sources would produce too much flux in the ultraviolet and soft Xray wavelengths Nevertheless we are able to explain both spectral components at microwave and submillimeter wavelengths by gyrosynchrotron emission from the same population of accelerated electrons that emit hard X rays and γ rays We find that the same 5×1035 electrons inferred from RHESSI observations are responsible for the compact submillimeter source 05 arcsec in radius in a region of 4500 G low in the atmosphere and for the traditional microwave spectral component by a more extended source 50 arcsec in a 480 G magnetic field located higher up in the loops The extreme values in magnetic field and source size required to account for the submillimeter emission can be relaxed if anisotropy and transport of the electrons are taken into account


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Other Papers In This Journal:

  1. Coronal Mass Ejections from the Same Active Region Cluster: Two Different Perspectives
  2. Gnevyshev Peaks in the CME Average Speeds in Cycle 23
  3. Mapping Solar Wind Streams from the Sun to 1 AU: A Comparison of Techniques
  4. Non-reflective Propagation of Kink Waves in Coronal Magnetic Loops
  5. High-Energy Emission from a Solar Flare in Hard X-rays and Microwaves
  6. Estimating Electric Current Densities in Solar Active Regions
  7. Total Solar Irradiance Measurement and Modelling during Cycle 23
  8. Reduced Coronal Emission Above Large Isolated Sunspots
  9. Observational Signatures of Impulsively Heated Coronal Loops: Power-Law Distribution of Energies
  10. Transition of the Sunspot Number from Zurich to Brussels in 1980: A Personal Perspective
  11. Very High-Resolution Solar X-Ray Imaging Using Diffractive Optics
  12. Tracking of Coronal White-Light Events by Texture
  13. An Interpretation of a Possible Mechanism for the First Ground-Level Enhancement of Solar Cycle 24
  14. Velocities and Temperatures of an Ellerman Bomb and Its Associated Features
  15. Kink Wave Propagation in Thin Isothermal Magnetic Flux Tubes
  16. Ensemble Modeling of CMEs Using the WSA–ENLIL+Cone Model
  17. A Simple Way to Estimate the Soft X-ray Class of Far-Side Solar Flares Observed with STEREO/EUVI
  18. Multi-spacecraft Observations of CIR-Associated Ion Increases During the Ulysses 2007 Ecliptic Crossing
  19. Numerical Simulation of a Solar Active Region. I: Bastille Day Flare
  20. Magnetic Topology of Active Regions and Coronal Holes: Implications for Coronal Outflows and the Solar Wind
  21. Variations in Ratio and Correlation of Solar Magnetic Fields in the Fe i 525.02 nm and Na i 589.59 nm Lines According to Mount Wilson Measurements During 2000 – 2012
  22. Oscillations in Solar Faculae. III. The Phase Relations Between Chromospheric and Photospheric Line-of-Sight Velocities
  23. A Search for Helioseismic Signature of Emerging Active Regions
  24. Subsecond (0.1 s) Pulsations in the 11 April 2001 Radio Event
  25. Global Heliospheric Parameters and Cosmic-Ray Modulation: An Empirical Relation for the Last Decades
  26. Modeling of EIS Spectrum Drift from Instrumental Temperatures
  27. Preface
  28. Emission of Type II Radio Bursts – Single-Beam Versus Two-Beam Scenario
  29. Historical Heliophysical Series of the Ebro Observatory
  30. Dynamics of an Erupting Arched Magnetic Flux Rope in a Laboratory Plasma Experiment
  31. Eclipses Observed by Large Yield RAdiometer (LYRA) – A Sensitive Tool to Test Models for the Solar Irradiance
  32. The Self-Inversion of the Sign of Circular Polarization in “Halo” Microwave Sources
  33. Recent Developments of NEMO: Detection of EUV Wave Characteristics
  34. Design and Ground Calibration of the Helioseismic and Magnetic Imager (HMI) Instrument on the Solar Dynamics Observatory (SDO)
  35. Preface

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