scholarly journals Gamma-ray line features from the Crab Nebula in the energy range 50-2000 keV

1983 ◽  
Vol 205 (2) ◽  
pp. 285-295 ◽  
Author(s):  
C. A. Ayre ◽  
P. N. Bhat ◽  
Y. Q. Ma ◽  
R. M. Myers ◽  
M. G. Thompson
Keyword(s):  
Energy Range ◽  
Gamma Ray ◽  
Crab Nebula ◽  
Line Features ◽  
The Crab Nebula

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 Gamma-ray flux depressions of the Crab Nebula in the high-energy range

2020 ◽  
Vol 496 (4) ◽  
pp. 5227-5232
Author(s):  
M S Pshirkov ◽  
B A Nizamov ◽  
A M Bykov ◽  
Yu A Uvarov
Keyword(s):  
Energy Range ◽  
Gamma Ray ◽  
Crab Nebula ◽  
High Energy ◽  
Synchrotron Emission ◽  
Pulsar Wind Nebulae ◽  
Average Value ◽  
Order Of Magnitude ◽  
Pulsar Wind ◽  
The Crab Nebula

ABSTRACT The giant gamma-ray flares of the Crab Nebula discovered by AGILE and Fermi observatories came as a surprise and have challenged the existing models of pulsar wind nebulae. We have carried out an analysis of 10.5 yr of Fermi-LAT observations (August 2008 to February 2019) and investigated variability of the Crab Nebula in the 100–300 MeV range. Besides the flares, we found several month long depressions of the gamma-ray flux and identified several cases of sharp flux drops, where during 1 week the flux decreased by an order of magnitude with respect to its average value. No statistically significant variations of the nebula flux in the E > 10 GeV range were found in the data. We discuss possible implications of the observed gamma-ray flux depressions on the model of synchrotron emission of the Crab Nebula.

scholarly journals The Crab nebula variability at short time-scales with the Cherenkov telescope array

2020 ◽  
Vol 501 (1) ◽  
pp. 337-346
Author(s):  
E Mestre ◽  
E de Oña Wilhelmi ◽  
D Khangulyan ◽  
R Zanin ◽  
F Acero ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
Spectral Energy Distribution ◽  
Spectral Energy ◽  
Telescope Array ◽  
Cherenkov Telescopes ◽  
Cherenkov Telescope ◽  
Emission Models ◽  
Short Time ◽  
The Crab Nebula

ABSTRACT Since 2009, several rapid and bright flares have been observed at high energies (>100 MeV) from the direction of the Crab nebula. Several hypotheses have been put forward to explain this phenomenon, but the origin is still unclear. The detection of counterparts at higher energies with the next generation of Cherenkov telescopes will be determinant to constrain the underlying emission mechanisms. We aim at studying the capability of the Cherenkov Telescope Array (CTA) to explore the physics behind the flares, by performing simulations of the Crab nebula spectral energy distribution, both in flaring and steady state, for different parameters related to the physical conditions in the nebula. In particular, we explore the data recorded by Fermi during two particular flares that occurred in 2011 and 2013. The expected GeV and TeV gamma-ray emission is derived using different radiation models. The resulting emission is convoluted with the CTA response and tested for detection, obtaining an exclusion region for the space of parameters that rule the different flare emission models. Our simulations show different scenarios that may be favourable for achieving the detection of the flares in Crab with CTA, in different regimes of energy. In particular, we find that observations with low sub-100 GeV energy threshold telescopes could provide the most model-constraining results.

VHE gamma-ray observation of the crab nebula with pulse shape discrimination to reduce the cosmic-ray background

1990 ◽  
Vol 14 (1) ◽  
pp. 176-179 ◽  
Author(s):  
O.Tumay Tumer ◽  
Jeffrey S. Hammond ◽  
Allen D. Zych ◽  
Crawford Maccallum
Keyword(s):  
Pulse Shape ◽  
Gamma Ray ◽  
Crab Nebula ◽  
Cosmic Ray ◽  
Pulse Shape Discrimination ◽  
Shape Discrimination ◽  
The Crab Nebula

scholarly journals Chambre à étincelles optique pour la recherche de sources de rayons gamma

1971 ◽  
Vol 41 ◽  
pp. 79-86
Author(s):  
J. Vasseur ◽  
J. Paul ◽  
B. Parlier ◽  
J. P. Leray ◽  
M. Forichon ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Plastic Scintillator ◽  
Crab Nebula ◽  
Time Of Arrival ◽  
Gamma Emission ◽  
Cerenkov Counter ◽  
Stereo Camera ◽  
Millisecond Accuracy ◽  
The Crab Nebula

A gamma-ray telescope with a 850 cm2 multiplate spark chamber as a detector, has been used in an experiment of six balloon flights to investigate the Crab Nebula Pulsar 0532. The triggering signal is provided by a plastic scintillator-directional Čerenkov counter system. The spark chamber events are photographed by a stereo camera. The time of arrival of each event is recorded in UTC time with one millisecond accuracy, to search for a possible pulsed gamma emission from NP0532 above 50 MeV.

VERITAS Prototype Performance and Construction Status

2005 ◽  
Vol 20 (14) ◽  
pp. 3154-3155
Author(s):  
◽  
T. B. HUMENSKY
Keyword(s):  
Energy Band ◽  
Gamma Ray ◽  
Crab Nebula ◽  
Cherenkov Telescopes ◽  
Gamma Ray Astronomy ◽  
The Crab Nebula

VERITAS is an array of 12-m imaging air-Cherenkov telescopes dedicated to gamma-ray astronomy in the 50 GeV - 50 TeV energy band. A prototype telescope was successfully operated between September 2003 and April 2004, yielding detections of the Crab Nebula and Mrk421 blazar. Construction has begun on the full array.

scholarly journals Time-Domain Astronomy with Swift, Fermi and Lobster

2011 ◽  
Vol 7 (S285) ◽  
pp. 41-46 ◽  
Author(s):  
Neil Gehrels ◽  
Scott D. Barthelmy ◽  
John K. Cannizzo
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
High Energy ◽  
Tidal Disruption ◽  
X Ray ◽  
Order Of Magnitude ◽  
New Type ◽  
The Crab Nebula ◽  
High Energy Emission ◽  
Higher Sensitivity

AbstractThe dynamic transient gamma-ray sky is revealing many interesting results, largely due to findings by Fermi and Swift. The list includes new twists on gamma-ray bursts (GRBs), a GeV flare from a symbiotic star, GeV flares from the Crab Nebula, high-energy emission from novae and supernovae, and, within the last year, a new type of object discovered by Swift—a jetted tidal disruption event. In this review we present highlights of these exciting discoveries. A new mission concept called Lobster is also described; it would monitor the X-ray sky at order-of-magnitude higher sensitivity than current missions can.

A search for gamma-ray lines from Nova Cygni 1975, Nova Serpentis 1970, and the Crab Nebula

1977 ◽  
Vol 216 ◽  
pp. 491 ◽  
Author(s):  
M. Leventhal ◽  
C. MacCallum ◽  
A. Watts
Keyword(s):  
Gamma Ray ◽  
Crab Nebula ◽  
The Crab Nebula
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