Simultaneous space-based observations of terrestrial gamma-ray flashes and lightning optical emissions: Investigation of the terrestrial gamma-ray flash production mechanisms

2019 ◽  
Vol 100 (8) ◽  
Author(s):  
Samer T. Alnussirat ◽  
Hugh J. Christian ◽  
Gerald J. Fishman ◽  
Jeffrey Burchfield ◽  
Michael L. Cherry
Keyword(s):  
Gamma Ray ◽  
Optical Emissions ◽  
Production Mechanisms

scholarly journals Molecular Clouds Observed by the EGRET Gamma-Ray Telescope

1997 ◽  
Vol 170 ◽  
pp. 22-24 ◽  
Author(s):  
Seth. W. Digel ◽  
Stanley D. Hunter ◽  
Reshmi Mukherjee ◽  
Eugéne J. de Geus ◽  
Isabelle A. Grenier ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Molecular Clouds ◽  
Gamma Ray ◽  
Angular Resolution ◽  
Cosmic Ray ◽  
High Energy ◽  
Background Rejection ◽  
Γ Rays ◽  
Γ Ray ◽  
Production Mechanisms

EGRET, the high-energy γ-ray telescope on the Compton Gamma-Ray Observatory, has the sensitivity, angular resolution, and background rejection necessary to study diffuse γ-ray emission from the interstellar medium (ISM). High-energy γ rays produced in cosmic-ray (CR) interactions in the ISM can be used to determine the CR density and calibrate the CO line as a tracer of molecular mass. Dominant production mechanisms for γ rays of energies ∼30 MeV–30 GeV are the decay of pions produced in collisions of CR protons with ambient matter and Bremsstrahlung scattering of CR electrons.

scholarly journals Spectral Observations of Optical Emissions Associated with Terrestrial Gamma-Ray Flashes

2020 ◽  
Author(s):  
Matthias Heumesser ◽  
Olivier Chanrion ◽  
Torsten Neubert ◽  
Hugh Christian ◽  
Christoph Koehn ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Optical Emissions

scholarly journals Asymmetry in Supernovae

2011 ◽  
Vol 7 (S279) ◽  
pp. 261-268
Author(s):  
Keiichi Maeda
Keyword(s):  
Spherical Symmetry ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Core Collapse ◽  
Late Time ◽  
Innermost Part ◽  
Optical Emissions ◽  
Standard Candle ◽  
Different Types ◽  
Bipolar Type

AbstractAsymmetry in the innermost part of the supernova (SN) ejecta is a key to understanding their explosion mechanisms. Late-time spectroscopy is a powerful tool to investigate the issue. We show what kind of geometry is inferred for different types of SNe – core-collapse SNe Ib/c, those associated with Gamma-Ray Bursts (GRBs), and thermonuclear SNe Ia –, and discuss implications for the explosion mechanisms, observational diversities, and cosmological applications. For SNe Ib/c, the data show the clear deviation from spherical symmetry, and they are most consistent with the bipolar-type explosion as the characteristic geometry. Detailed modeling of optical emissions from SN 1998bw associated with GRB980425 indicates that this SN was in the extreme end of the bipolar explosion, suggesting that the explosion mechanisms of canonical SNe Ib/c and GRB-SNe are different. The situation is different for SNe Ia. Late-time spectra indicate the deviation from spherical symmetry, but for SNe Ia the explosion is asymmetric between two hemispheres, i.e., one-sided explosions. The diversities arising from different viewing directions can nicely explain (a part of) observational diversities of SNe Ia, and correcting this effect may improve the standard-candle calibration of SNe Ia for cosmology.

scholarly journals GRB 060607A: a gamma-ray burst with bright asynchronous early X-ray and optical emissions

2008 ◽  
Vol 385 (1) ◽  
pp. 453-467 ◽  
Author(s):  
Houri Ziaeepour ◽  
Stephen T. Holland ◽  
Patricia T. Boyd ◽  
Kim Page ◽  
Samantha Oates ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Burst ◽  
X Ray ◽  
Optical Emissions

scholarly journals The Energetic Particle Population in Centaurus A

2016 ◽  
Vol 12 (S324) ◽  
pp. 211-214
Author(s):  
Paula Chadwick ◽  
Anthony M. Brown ◽  
Celine Boehm ◽  
Jamie Graham ◽  
Thomas Lacroix ◽  
...  
Keyword(s):  
Dark Matter ◽  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
High Energy ◽  
Dark Matter Halo ◽  
The Core ◽  
Particle Population ◽  
High Energy Particles ◽  
Production Mechanisms

AbstractWe report a significant hardening of theFermi-LAT gamma-ray spectrum from the core of Cen A at E > 2.4 GeV, suggesting there is a source of high energy particles in the core of Cen A which is in addition to the jet component. We show that the observed gamma-ray spectrum is compatible with either a spike in the dark matter halo profile or a population of millisecond pulsars. This work gives a strong indication of new gamma-ray production mechanisms in active galactic nuclei and could even provide evidence for the clustering of heavy dark matter particles around black holes.

scholarly journals Spectral Observations of Optical Emissions Associated with Terrestrial Gamma‐Ray Flashes

2020 ◽  
Author(s):  
Matthias Heumesser ◽  
Olivier Chanrion ◽  
Torsten Neubert ◽  
Hugh Christian ◽  
Krystallia Dimitriadou ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Optical Emissions

scholarly journals Optical emissions associated with terrestrial gamma ray flashes

2015 ◽  
Vol 120 (2) ◽  
pp. 1355-1370 ◽  
Author(s):  
Wei Xu ◽  
Sebastien Celestin ◽  
Victor P. Pasko
Keyword(s):  
Gamma Ray ◽  
Optical Emissions

Modeling terrestrial gamma-ray flashes observed by ASIM

2020 ◽  
Author(s):  
Joseph Dwyer
Keyword(s):  
High Field ◽  
Runaway Electron ◽  
Gamma Ray ◽  
Space Station ◽  
Feedback Mechanism ◽  
X Rays ◽  
Runaway Electrons ◽  
International Space ◽  
Electron Production ◽  
Production Mechanisms

<p>The Atmosphere-Space Interactions Monitor (ASIM) on the International Space Station is providing important observations of terrestrial gamma-ray flashes (TGFs), including new measurements of optical emissions associated with TGFs and new measurements of multi-pulsed TGFs.  TGFs are thought to be produced by bremsstrahlung emissions from relativistic runaway electrons accelerated inside thunderstorms.  However, the exact mechanisms for generating the large number of runaway electrons required to account for the observed TGF luminosities remains an active area of debate.  Two mechanisms being considered are cold-runaway electron production by streamer heads or leader tips in the high-field regions near lightning, and the self-sustained production of runaway electrons by relativistic feedback involving backward propagating runaway positrons and backscattered x-rays.  Because both mechanisms may require the presence of lightning leaders inside thunderstorms -- for the cold-runaway mechanism to emit the runaway electrons and for the relativistic feedback mechanism to drive the electric field above the feedback threshold -- it has been challenging to test which TGF production mechanisms are occurring.  The new ASIM TGF observations should help constrain TGF models and possibly identify which mechanisms are primarily responsible for the runaway electron production.  In this talk, I will present new TGF modeling results and compare them with available ASIM observations.   </p>

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