scholarly journals Fermi LAT Flare Advocate Activity

2011 ◽  
Vol 7 (S285) ◽  
pp. 294-295 ◽  
Author(s):  
Stefano Ciprini ◽  
Dario Gasparrini ◽  
Denis Bastieri
Keyword(s):  
Gamma Ray ◽  
Galactic Center ◽  
Galactic Plane ◽  
Crab Nebula ◽  
High Energy ◽  
Cherenkov Telescopes ◽  
Duty Cycles ◽  
Energy Gamma ◽  
Galactic Sources ◽  
The Crab Nebula

AbstractThe Fermi Flare Advocate (also known as Gamma-ray Sky Watcher, FA-GSW) service provides a daily quick-look analysis and review of the high-energy gamma-ray sky seen by the Fermi Gamma-ray Space Telescope. The duty offers alerts for potentially new gamma-ray sources, interesting transients and flares. A weekly digest containing the highlights about the GeV gamma-ray sky is published in the web-based Fermi Sky Blog. During the first 3 years of all-sky survey, more than 150 Astronomical Telegrams, several alerts to the TeV Cherenkov telescopes, and targets of opportunity to Swift and other observatories, were realized. That increased the rate of simultaneous multi-frequency observing campaigns and the level of international cooperation. Many gamma-ray flares from blazars (such as extraordinary outbursts of 3C 454.3, intense flares of PKS 1510-089, 4C 21.35, PKS 1830-211, AO 0235+164, PKS 1502+106, 3C 279, 3C 273, PKS 1622-253), short/long flux duty cycles, unidentified transients near the Galactic plane (like J0910-5041, J0109+6134, the Galactic center region), flares associated with Galactic sources (like the Crab nebula, the nova V407 Cyg, the microquasar Cyg X-3), emission of the quiet and active sun, were observed by Fermi and communicated by FA-GSWs.

scholarly journals High-Energy Discrete Sources

1973 ◽  
Vol 55 ◽  
pp. 303-323 ◽  
Author(s):  
G. G. Fazio
Keyword(s):  
Gamma Radiation ◽  
Gamma Ray ◽  
Galactic Center ◽  
Galactic Plane ◽  
Crab Nebula ◽  
High Energy ◽  
Continuous Emission ◽  
X Ray ◽  
The Crab Nebula ◽  
Variable Radio

The origin of the gamma-radiation from the galactic plane and the region near the galactic center is still uncertain. However, during this meeting, several groups reported evidence for discrete sources of cosmic gamma-rays. Most of the sources are located near the galactic plane, and some are associated with X-ray sources. The galactic gamma-radiation may be due to these previously unresolved sources. Other sources detected may be associated with variable radio galaxies.The Crab Nebula still remains the most investigated source at gamma-ray energies. Pulsed emission from NP0532 was detected in the 10 to 30 MeV region, but no continuous emission was observed. At the highest energies, pulsed emission was reported at ∼1012 eV. Continuous emission from the Crab Nebula was observed at ∼1011 eV; the radiation may be time variable.The recent gamma-ray experiments on Apollo 15 and 16 and the ESRO satellite TD-1 are described, as well as future experiments on the satellites SAS-B, COS-B, and HEAO-B.

scholarly journals The H.E.S.S. Galactic plane survey

2018 ◽  
Vol 612 ◽  
pp. A1 ◽  
Author(s):  
◽  
H. Abdalla ◽  
A. Abramowski ◽  
F. Aharonian ◽  
F. Ait Benkhali ◽  
...  
Keyword(s):  
Supernova Remnants ◽  
Large Scale ◽  
Gamma Ray ◽  
Galactic Center ◽  
Galactic Plane ◽  
High Energy ◽  
High Angular Resolution ◽  
Data Set ◽  
Cherenkov Telescopes ◽  
Spatial Coverage

We present the results of the most comprehensive survey of the Galactic plane in very high-energy (VHE) γ-rays, including a public release of Galactic sky maps, a catalog of VHE sources, and the discovery of 16 new sources of VHE γ-rays. The High Energy Spectroscopic System (H.E.S.S.) Galactic plane survey (HGPS) was a decade-long observation program carried out by the H.E.S.S. I array of Cherenkov telescopes in Namibia from 2004 to 2013. The observations amount to nearly 2700 h of quality-selected data, covering the Galactic plane at longitudes from ℓ = 250° to 65° and latitudes |b|≤ 3°. In addition to the unprecedented spatial coverage, the HGPS also features a relatively high angular resolution (0.08° ≈ 5 arcmin mean point spread function 68% containment radius), sensitivity (≲1.5% Crab flux for point-like sources), and energy range (0.2–100 TeV). We constructed a catalog of VHE γ-ray sources from the HGPS data set with a systematic procedure for both source detection and characterization of morphology and spectrum. We present this likelihood-based method in detail, including the introduction of a model component to account for unresolved, large-scale emission along the Galactic plane. In total, the resulting HGPS catalog contains 78 VHE sources, of which 14 are not reanalyzed here, for example, due to their complex morphology, namely shell-like sources and the Galactic center region. Where possible, we provide a firm identification of the VHE source or plausible associations with sources in other astronomical catalogs. We also studied the characteristics of the VHE sources with source parameter distributions. 16 new sources were previously unknown or unpublished, and we individually discuss their identifications or possible associations. We firmly identified 31 sources as pulsar wind nebulae (PWNe), supernova remnants (SNRs), composite SNRs, or gamma-ray binaries. Among the 47 sources not yet identified, most of them (36) have possible associations with cataloged objects, notably PWNe and energetic pulsars that could power VHE PWNe.

scholarly journals High‐Energy Gamma‐Ray Observations of the Crab Nebula and Pulsar with the Solar Tower Atmospheric Cerenkov Effect Experiment

2001 ◽  
Vol 547 (2) ◽  
pp. 949-958 ◽  
Author(s):  
S. Oser ◽  
D. Bhattacharya ◽  
L. M. Boone ◽  
M. C. Chantell ◽  
Z. Conner ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
High Energy ◽  
High Energy Gamma ◽  
Energy Gamma ◽  
The Crab Nebula ◽  
Cerenkov Effect ◽  
Effect Experiment

scholarly journals Impact of H.E.S.S. Lidar profiles on Crab Nebula data

2019 ◽  
Vol 197 ◽  
pp. 01001 ◽  
Author(s):  
Justine Devin ◽  
Johan Bregeon ◽  
Georges Vasileiadis ◽  
Yves Gallant
Keyword(s):  
Energy Range ◽  
Photon Energy ◽  
Gamma Ray ◽  
Crab Nebula ◽  
Systematic Errors ◽  
High Energy ◽  
Atmospheric Composition ◽  
Direct Impact ◽  
Energy Gamma ◽  
The Crab Nebula

The H.E.S.S. experiment in Namibia is a high-energy gamma-ray telescope sensitive in the energy range from 30 GeV to a several tens of TeV, that uses the atmospheric Cherenkov technique to detect showers developed within the atmosphere. The elastic lidar, installed on the H.E.S.S. site, allows to reduce the systematic errors related to the atmospheric composition uncertainties thanks to the estimation of the extinction profile for the Cherenkov light (300-650 nm). The latter has a direct impact on the reconstructed parameters, such as the photon energy and the source flux. In this paper we report on physics results obtained on the Crab Nebula spectrum using the lidar profiles obtained at the H.E.S.S. site.

scholarly journals The Crab Pulsar and Nebula as Seen in Gamma-Rays

Universe ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 448
Author(s):  
Elena Amato ◽  
Barbara Olmi
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
High Energy ◽  
Crab Pulsar ◽  
Gamma Ray Astronomy ◽  
Very High Energy ◽  
Energy Gamma ◽  
The Crab Nebula ◽  
The Impact ◽  
Very High

Slightly more than 30 years ago, Whipple detection of the Crab Nebula was the start of Very High Energy gamma-ray astronomy. Since then, gamma-ray observations of this source have continued to provide new surprises and challenges to theories, with the detection of fast variability, pulsed emission up to unexpectedly high energy, and the very recent detection of photons with energy exceeding 1 PeV. In this article, we review the impact of gamma-ray observations on our understanding of this extraordinary accelerator.

Chapter 2 Galactic Gamma-ray Sources

2021 ◽  
Author(s):  
Yang Chen ◽  
Xiao Zhang
Keyword(s):  
Supernova Remnants ◽  
Gamma Ray ◽  
Galactic Center ◽  
Galactic Plane ◽  
Theoretical Models ◽  
High Energy ◽  
Maximum Energy ◽  
Radiation Mechanisms ◽  
Galactic Sources ◽  
Very High

Abstract In the gamma-ray sky, the highest fluxes come from Galactic sources: supernova remnants (SNRs), pulsars and pulsar wind nebulae, star forming regions, binaries and micro-quasars, giant molecular clouds, Galactic center, and the large extended area around the Galactic plane. The radiation mechanisms of -ray emission and the physics of the emitting particles, such as the origin, acceleration, and propagation, are of very high astrophysical significance. A variety of theoretical models have been suggested for the relevant physics and emission with energies E_1014 eV are expected to be crucial in testing them. In particular, this energy band is a direct window to test at which maximum energy a particle can be accelerated in the Galactic sources and whether the most probable source candidates such as Galactic center and SNRs are “PeVatrons”. Designed aiming at the very high energy (VHE, >100 GeV) observation, LHAASO will be a very powerful instrument in these astrophysical studies. Over the past decade, great advances have been made in the VHE -ray astronomy. More than 170 VHE -ray sources have been observed, and among them, 42 Galactic sources fall in the LHAASO field-of-view. With a sensitivity of 10 milli-Crab, LHAASO can not only provide accurate spectrum for the known -ray sources, but also search new TeV -ray sources. In the following sub-sections, the observation of all the Galactic sources with LHAASO will be discussed in details.

The ultra-high energy gamma-ray burst from the Crab Nebula observed by the Baksan EAS array

1992 ◽  
Vol 18 (4) ◽  
pp. L83-L88 ◽  
Author(s):  
V V Alexeenko ◽  
Y M Andreyev ◽  
A E Chudakov ◽  
Y S Elensky ◽  
A S Lidvansky ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
High Energy ◽  
Ultra High Energy ◽  
Gamma Ray Burst ◽  
High Energy Gamma ◽  
Energy Gamma ◽  
The Crab Nebula

A Search for Ultra–High‐Energy Gamma‐Ray Emission from the Crab Nebula and Pulsar

1997 ◽  
Vol 481 (1) ◽  
pp. 313-326 ◽  
Author(s):  
A. Borione ◽  
M. A. Catanese ◽  
M. C. Chantell ◽  
C. E. Covault ◽  
J. W. Cronin ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
High Energy ◽  
Ultra High Energy ◽  
High Energy Gamma ◽  
Energy Gamma ◽  
Gamma Ray Emission ◽  
The Crab Nebula

Upper limit to the number of galactic sources of ultra-high-energy gamma-rays

1989 ◽  
Vol 8 (2) ◽  
pp. 159-160 ◽  
Author(s):  
D. J. Bird ◽  
R. W. Clay ◽  
P. G. Edwards
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
Galactic Plane ◽  
Cosmic Ray ◽  
High Energy ◽  
Ultra High Energy ◽  
Upper Limits ◽  
Energy Gamma ◽  
Galactic Sources ◽  
Cosmic Ray Flux

AbstractThe extreme isotropy of cosmic ray events allows one to put upper limits on any possible non-isotropic contribution to the flux. In particular, one can investigate any excess of events which may be confined to the galactic plane. Such extra events would be expected from galactic ultra-high-energy (UHE) gamma-ray sources. Under the assumption of an isotropic cosmic ray flux, recent Buckland Park data place a 95% confidence level limit on the total southern hemisphere (declination −15° to −55°) flux of UHE gamma-rays at between 0.6 and 6 equivalent Cygnus X-3 sources, depending on assumptions concerning the gamma-ray spectrum.

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