scholarly journals Pulsar Geometrodynamics: Relativistic Radiative Plasma Theory and its Associated Quantum Phenomena

2000 ◽  
Vol 195 ◽  
pp. 385-386
Author(s):  
A. A. da Costa
Keyword(s):  
Kinetic Theory ◽  
Quantum Electrodynamics ◽  
Gamma Ray ◽  
Radiative Processes ◽  
High Energies ◽  
Plasma Motion ◽  
Curvature Radiation ◽  
Plasma Theory ◽  
Quantum Phenomena

Plasma motion in pulsar magnetospheres is quasi-classical due to curvature radiation of highly energetic gamma-ray photons, implying an extension to the kinetic theory of plasmas. But with high energies involved, other quantum radiative processes become important in the context of vacuum (quantum) electrodynamics.

scholarly journals Pulsar Magnetospheres: Classical, Quasi-Classical and Quantum Descriptions

2000 ◽  
Vol 177 ◽  
pp. 457-460
Author(s):  
A. A. da Costa
Keyword(s):  
Kinetic Theory ◽  
Quantum Electrodynamics ◽  
Gamma Ray ◽  
Radiation Mechanisms ◽  
Radiative Processes ◽  
High Energies ◽  
Curvature Radiation ◽  
Pulsar Radiation ◽  
Relativistic Kinetic Theory ◽  
Random Curvature

AbstractThe plasma motion in pulsar magnetospheres is no longer classical, but quasi-classical, following stochastic trajectories, when random curvature radiation of high energetic gamma-ray photons takes place. This implies an extension to the relativistic kinetic theory of plasmas. But with high energies involved other quantum radiative processes become important, in the context of vacuum (quantum) electrodynamics. The consequences for pulsar radiation mechanisms will be outlined.

scholarly journals The response of an autonomous underwater telescope to high energy neutrinos for the observation of Gamma-ray bursts (GRBs)

2019 ◽  
Vol 22 ◽  
pp. 88
Author(s):  
K. Balasi ◽  
C. Markou ◽  
K. Tzamarioudaki ◽  
P. Rapidis ◽  
E. Drakopoulou ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Simulation Program ◽  
Neutrino Detector ◽  
High Energies ◽  
Analytical Studies ◽  
High Energy Neutrinos ◽  
Detector Simulation ◽  
Fast Detector

The response of an underwater neutrino detector is discussed for investigating its performance to the detection of muons and high energy neutrinos. The afformentioned telescope consists of an autonomous battery operated detector string to a central 4-floor tower. In this aim, we utilised a fast detector simulation program, SIRENE, to simulate the hits from Cherenkov photons at ultra high energies (as high as 1020 eV). In order to optimize the detector, analytical studies for different configurations and characteristics of the photo-multiplier tubes inside the optical modules of the telescope was also examined.

scholarly journals Detection of the Geminga pulsar with MAGIC hints at a power-law tail emission beyond 15 GeV

2020 ◽  
Vol 643 ◽  
pp. L14
Author(s):  
◽  
V. A. Acciari ◽  
S. Ansoldi ◽  
L. A. Antonelli ◽  
A. Arbet Engels ◽  
...  
Keyword(s):  
Energy Range ◽  
Power Law ◽  
Gamma Ray ◽  
Low Energy ◽  
Significance Level ◽  
Inverse Compton Scattering ◽  
Curvature Radiation ◽  
Sensitivity Range ◽  
Inverse Compton ◽  
First Time

We report the detection of pulsed gamma-ray emission from the Geminga pulsar (PSR J0633+1746) between 15 GeV and 75 GeV. This is the first time a middle-aged pulsar has been detected up to these energies. Observations were carried out with the MAGIC telescopes between 2017 and 2019 using the low-energy threshold Sum-Trigger-II system. After quality selection cuts, ∼80 h of observational data were used for this analysis. To compare with the emission at lower energies below the sensitivity range of MAGIC, 11 years of Fermi-LAT data above 100 MeV were also analysed. From the two pulses per rotation seen by Fermi-LAT, only the second one, P2, is detected in the MAGIC energy range, with a significance of 6.3σ. The spectrum measured by MAGIC is well-represented by a simple power law of spectral index Γ = 5.62 ± 0.54, which smoothly extends the Fermi-LAT spectrum. A joint fit to MAGIC and Fermi-LAT data rules out the existence of a sub-exponential cut-off in the combined energy range at the 3.6σ significance level. The power-law tail emission detected by MAGIC is interpreted as the transition from curvature radiation to Inverse Compton Scattering of particles accelerated in the northern outer gap.

scholarly journals High-energy emission from gamma-ray bursts

2018 ◽  
Vol 27 (13) ◽  
pp. 1842003 ◽  
Author(s):  
Lara Nava
Keyword(s):  
Gamma Ray ◽  
Theoretical Models ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Quality Of Data ◽  
Large Area ◽  
High Energies ◽  
Energy Emission ◽  
High Energy Emission ◽  
Very High

The number of gamma-ray bursts (GRBs) detected at high energies ([Formula: see text][Formula: see text]GeV) has seen a rapid increase over the last decade, thanks to observations from the Fermi-Large Area Telescope. The improved statistics and quality of data resulted in a better characterization of the high-energy emission properties and in stronger constraints on theoretical models. In spite of the many achievements and progresses, several observational properties still represent a challenge for theoretical models, revealing how our understanding is far from being complete. This paper reviews the main spectral and temporal properties of [Formula: see text][Formula: see text]GeV emission from GRBs and summarizes the most promising theoretical models proposed to interpret the observations. Since a boost for the understanding of GeV radiation might come from observations at even higher energies, the present status and future prospects for observations at very-high energies (above [Formula: see text][Formula: see text]100[Formula: see text]GeV) are also discussed. The improved sensitivity of upcoming facilities, coupled to theoretical predictions, supports the concrete possibility for future ground GRB detections in the high/very-high energy domain.

scholarly journals Future Facilities for Gamma-Ray Pulsar Studies

2004 ◽  
Vol 218 ◽  
pp. 399-406
Author(s):  
D. J. Thompson
Keyword(s):  
Particle Acceleration ◽  
Neutron Stars ◽  
Gamma Ray ◽  
Large Area ◽  
Space Telescope ◽  
High Energies ◽  
Interaction Processes ◽  
Very High ◽  
Insight Into

Pulsars seen at gamma-ray energies offer insight into particle acceleration to very high energies, along with information about the geometry and interaction processes in the magnetospheres of these rotating neutron stars. During the next decade, a number of new gamma-ray facilities will become available for pulsar studies. This brief review describes the motivation for gamma-ray pulsar studies, the opportunities for such studies, and some specific discussion of the capabilities of the Gamma-ray Large Area Space Telescope (GLAST) Large Area Telescope (LAT) for pulsar measurements.

scholarly journals VHE observations of binary systems performed with the MAGIC telescopes

2018 ◽  
Vol 27 (10) ◽  
pp. 1844010 ◽  
Author(s):  
Alicia López-Oramas ◽  
Oscar Blanch ◽  
Emma de Oña Wilhelmi ◽  
Alba Fernández-Barral ◽  
Daniela Hadasch ◽  
...  
Keyword(s):  
Binary Systems ◽  
Gamma Ray ◽  
Optical Observations ◽  
Ss 433 ◽  
High Energies ◽  
New Type ◽  
Gamma Ray Emitters ◽  
Term Monitoring ◽  
Very High

The improvement on the Imaging Air Cherenkov Technique (IACT) led to the discovery of a new type of sources that can emit at very high energies: the gamma-ray binaries. Only six systems are part of this exclusive class. We summarize the latest results from the observations performed with the MAGIC telescopes on different systems as the gamma-ray binary LS I [Formula: see text]303 and the microquasars SS 433, V404 Cygni and Cygnus X-1, which are considered potential VHE gamma-ray emitters. The binary system LS I [Formula: see text] 303 has been observed by MAGIC in a long-term monitoring campaign. We show the newest results of our search for super-orbital variability also in context of contemporaneous optical observations. Besides, we will present the results of the only super-critical accretor known in our galaxy: SS 433. We will introduce the VHE results achieved with MAGIC after 100[Formula: see text]h of observations on the microquasar Cygnus X-1 and report on the microquasar V404 Cyg, which has been observed with MAGIC after it went through a series of exceptional X-ray outbursts in June 2015.

scholarly journals The supernova remnant W49B as seen with H.E.S.S. and Fermi-LAT

2018 ◽  
Vol 612 ◽  
pp. A5 ◽  
Author(s):  
◽  
H. Abdalla ◽  
A. Abramowski ◽  
F. Aharonian ◽  
F. Ait Benkhali ◽  
...  
Keyword(s):  
Supernova Remnant ◽  
Gamma Ray ◽  
Surrounding Medium ◽  
High Energy ◽  
Galactic Cosmic Rays ◽  
Source Spectrum ◽  
Cherenkov Telescopes ◽  
High Energies ◽  
Very High ◽  
Subsequent Emission

The supernova remnant (SNR) W49B originated from a core-collapse supernova that occurred between one and four thousand years ago, and subsequently evolved into a mixed-morphology remnant, which is interacting with molecular clouds (MC). Gamma-ray observations of SNR-MC associations are a powerful tool to constrain the origin of Galactic cosmic rays, as they can probe the acceleration of hadrons through their interaction with the surrounding medium and subsequent emission of non-thermal photons. We report the detection of a γ-ray source coincident with W49B at very high energies (VHE; E > 100 GeV) with the H.E.S.S. Cherenkov telescopes together with a study of the source with five years of Fermi-LAT high-energy γ-ray (0.06–300 GeV) data. The smoothly connected, combined source spectrum, measured from 60 MeV to multi-TeV energies, shows two significant spectral breaks at 304 ± 20 MeV and 8.4−2.5+2.2 GeV; the latter is constrained by the joint fit from the two instruments. The detected spectral features are similar to those observed in several other SNR-MC associations and are found to be indicative of γ-ray emission produced through neutral-pion decay.

The form of the divergencies in quantum electrodynamics

1956 ◽  
Vol 234 (1197) ◽  
pp. 296-300 ◽  
Keyword(s):  
Quantum Electrodynamics ◽  
Functional Equations ◽  
Asymptotic Form ◽  
Particle Charge ◽  
High Energies ◽  
Renormalization Constants

The results of Landau and his collaborators on the asymptotic form of the propagators for high energies and the dependence of the renormalization constants on the cut-off are re­-derived, starting from the functional equations of Gell-Mann & Low. It is proved further that, in electrodynamics, the cut-off cannot be made arbitrarily large, without the ‘bare-particle’ charge becoming imaginary.

Probability of Radiative Processes for Very High Energies

1936 ◽  
Vol 49 (2) ◽  
pp. 189-191 ◽  
Author(s):  
L. W. Nordheim
Keyword(s):  
Radiative Processes ◽  
High Energies ◽  
Very High
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