Systematic Low-Energy Enhancement of the Gamma-Ray Strength Function

2019 ◽  
pp. 405-407
Author(s):  
J. E. Midtbø ◽  
A. C. Larsen ◽  
T. Renstrøm ◽  
F. L. Bello Garrote ◽  
E. Lima
Keyword(s):  
Gamma Ray ◽  
Strength Function ◽  
Low Energy

scholarly journals Limits on quantum gravity effects from Swift short gamma-ray bursts

2017 ◽  
Vol 607 ◽  
pp. A121 ◽  
Author(s):  
M. G. Bernardini ◽  
G. Ghirlanda ◽  
S. Campana ◽  
P. D’Avanzo ◽  
J.-L. Atteia ◽  
...  
Keyword(s):  
Quantum Gravity ◽  
Gamma Ray ◽  
Lorentz Invariance ◽  
Spectral Energy Distribution ◽  
Gamma Ray Bursts ◽  
Low Energy ◽  
Energy Separation ◽  
Spectral Energy ◽  
Spectral Evolution ◽  
Short Grbs

The delay in arrival times between high and low energy photons from cosmic sources can be used to test the violation of the Lorentz invariance (LIV), predicted by some quantum gravity theories, and to constrain its characteristic energy scale EQG that is of the order of the Planck energy. Gamma-ray bursts (GRBs) and blazars are ideal for this purpose thanks to their broad spectral energy distribution and cosmological distances: at first order approximation, the constraints on EQG are proportional to the photon energy separation and the distance of the source. However, the LIV tiny contribution to the total time delay can be dominated by intrinsic delays related to the physics of the sources: long GRBs typically show a delay between high and low energy photons related to their spectral evolution (spectral lag). Short GRBs have null intrinsic spectral lags and are therefore an ideal tool to measure any LIV effect. We considered a sample of 15 short GRBs with known redshift observed by Swift and we estimate a limit on EQG ≳ 1.5 × 1016 GeV. Our estimate represents an improvement with respect to the limit obtained with a larger (double) sample of long GRBs and is more robust than the estimates on single events because it accounts for the intrinsic delay in a statistical sense.

C-SPRINT: a prototype Compton camera system for low energy gamma ray imaging

2002 ◽  
Author(s):  
J.W. LeBlanc ◽  
N.H. Clinthorne ◽  
C.-H. Hua ◽  
E. Nygard ◽  
W.L. Rogers ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Low Energy ◽  
Compton Camera ◽  
Camera System ◽  
Gamma Ray Imaging ◽  
Energy Gamma

scholarly journals Constraints on the late X-ray radiation from the low-energy gamma-ray burst of December 3, 2003: INTEGRAL data

2006 ◽  
Vol 32 (5) ◽  
pp. 297-301 ◽  
Author(s):  
S. Yu. Sazonov ◽  
A. A. Lutovinov ◽  
E. M. Churazov ◽  
R. A. Sunyaev
Keyword(s):  
Gamma Ray ◽  
Low Energy ◽  
Gamma Ray Burst ◽  
X Ray ◽  
Energy Gamma ◽  
Integral Data

Observations of the galactic center with the GSFC Low-Energy Gamma-Ray Spectrometer: Preliminary results

1982 ◽  
Author(s):  
W. S. Paciesas ◽  
T. L. Cline ◽  
B. J. Teegarden ◽  
J. Tueller ◽  
P. Durouchoux ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Galactic Center ◽  
Low Energy ◽  
Preliminary Results ◽  
Gamma Ray Spectrometer ◽  
Energy Gamma

Gamma-Ray Spectrum Analysis of Chang’E-1 for Lunar Detection

2010 ◽  
Vol 133 (5) ◽  
Author(s):  
Xu HongKun ◽  
Fang Fang ◽  
Ni Shijun ◽  
He Jianfeng ◽  
You Lei
Keyword(s):  
Spectral Characteristic ◽  
Spectrum Analysis ◽  
Gamma Ray ◽  
Low Energy ◽  
Elemental Abundance ◽  
Nuclear Engineering ◽  
Gamma Ray Spectrometer ◽  
Lunar Prospector ◽  
Spectrometer Data ◽  
Wavelet Methods

Gamma-ray spectrum analysis was essential for radioactive environmental monitoring, and it had been widely used in many areas of nuclear engineering. However, for the low-energy region of gamma-ray spectrum, weak peaks were contained in the fast-decreasing background, so it was difficult to extract characteristic information from original spectra. In order to get a better analytic result based on wavelet methods in frequency domain, we had processed the gamma-ray spectrometer data of Chang’E-1 and well extracted some useful information of spectral characteristic peaks. Then, we preliminarily mapped the distribution of net peak counts for potassium on lunar surface, which indirectly reflected the distribution of elemental abundance. At last, we compared our analytic result with that of Apollo and Lunar Prospector and found some consistencies and differences.

scholarly journals Convolutional Neural Networks for Low Energy Gamma-Ray Air Shower Identification with HAWC

2021 ◽  
Author(s):  
Ian Watson ◽  
Anushka Udara Abeysekara ◽  
Andrea Albert ◽  
Ruben Alfaro ◽  
César Alvarez ◽  
...  
Keyword(s):  
Neural Networks ◽  
Convolutional Neural Networks ◽  
Gamma Ray ◽  
Low Energy ◽  
Air Shower ◽  
Energy Gamma

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.

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