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.

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 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.

Sky survey of high-energy cosmic X-rays and spectral information on sources in the Crab nebula, Cygnus, and Scorpius

1968 ◽  
Vol 46 (10) ◽  
pp. S409-S413 ◽  
Author(s):  
Walter H. G. Lewin ◽  
George W. Clark ◽  
William B. Smith
Keyword(s):  
Crab Nebula ◽  
High Energy ◽  
X Rays ◽  
Coma Cluster ◽  
X Ray ◽  
Sky Survey ◽  
Upper Limits ◽  
Intensity Ratios ◽  
The Crab Nebula ◽  
Made In

A complete X-ray survey of the northern sky has been made in the energy range 20–100 keV. Spectra are given for Cyg X-1 and Tau X-1. Intensity ratios (Cyg X-1/Tau X-1) of 0.84 ± 0.10 and 1.30 ± 0.25 were derived in the 20–70 keV range from data obtained on July 19, 1966 and February 13, 1967, respectively. Observations on Sco X-1 and the Coma cluster show upper limits which are quite different from results reported by other groups.

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 Studying stellar explosions with Athena

2015 ◽  
Vol 11 (A29B) ◽  
pp. 243-243
Author(s):  
P. O'Brien ◽  
P. Jonker
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Spectral Energy ◽  
Intermediate Mass ◽  
Tidal Disruption ◽  
X Ray ◽  
Cosmic Vision ◽  
Esa Cosmic Vision ◽  
Supernova Explosions

AbstractAthena is the second large mission selected in the ESA Cosmic Vision plan. With its large collecting area, high spectral-energy resolution (X-IFU instrument) and impressive grasp (WFI instrument), Athena will truly revolutionise X-ray astronomy. The most prodigious sources of high-energy photons are often transitory in nature. Athena will provide the sensitivity and spectral resolution coupled with rapid response to enable the study of the dynamic sky. Potential sources include: distant Gamma-Ray Bursts to probe the reionisation epoch and find missing baryons in the cosmic web; tidal disruption events to reveal dormant supermassive and intermediate-mass black holes; and supernova explosions to understand progenitors and their environments. We illustrate Athenas capabilities and show how it will be able to constrain the nature of explosive transients including gas metallicity and dynamics.

scholarly journals High energy cosmic photons and neutrinos

1965 ◽  
Vol 23 ◽  
pp. 195-225
Author(s):  
R. J. Gould ◽  
G. R. Burbidge
Keyword(s):  
Supernova Remnants ◽  
Crab Nebula ◽  
Meson Production ◽  
Cosmic Ray ◽  
High Energy ◽  
Relativistic Electrons ◽  
X Ray ◽  
Hard Radiation ◽  
The Galaxy ◽  
The Crab Nebula

This review concentrates primarily on the problem of interpreting the recent X-ray and γ-ray observations of celestial sources. The expected fluxes of hard radiation from various processes are estimated (when possible) and are compared with the observations. We compute the synchrotron, bremsstrahlung, and (inverse) Compton spectra originating from relativistic electrons produced (via meson production) in the galaxy and intergalactic medium by cosmic ray nuclear collisions; the spectra from π°-decay are also computed. Neutron stars, stellar coronae, and supernova remnants are reviewed as possible X-ray sources. Special consideration is given to the processes in the Crab Nebula. Extragalactic objects as discrete sources of energetic photons are considered on the basis of energy requirements; special emphasis is given to the strong radio sources and the possibility of the emission of hard radiation during their formation. The problem of the detection of cosmic neutrinos is reviewed.As yet, no definite process can be identified with any of the observed fluxes of hard radiation, although a number of relevant conclusions can be drawn on the basis of the available preliminary observational results. In particular, some cosmogonical theories can be tested.

scholarly journals The electromagnetic spectrum of the Crab Nebula

1970 ◽  
Vol 37 ◽  
pp. 247-249
Author(s):  
Krishna M. V. Apparao
Keyword(s):  
Compton Scattering ◽  
Power Law ◽  
Crab Nebula ◽  
High Energy ◽  
Electromagnetic Spectrum ◽  
Microwave Region ◽  
X Ray ◽  
High Energy Electrons ◽  
Γ Ray ◽  
The Crab Nebula

The electromagnetic spectrum of the Crab Nebula has been determined experimentally in the radio, optical, and X-ray regions [1], in which it follows a power law of the type S(v) = Av−α, where S(v) is the power (in watts/m2 sec Hz), A and α are constants, and v is the frequency in Hz. Recent measurements [2–5], however, show a deviation from a power law in the microwave region (see Figure 1). In this paper, we investigate the origin of this deviation and calculate the γ-Ray spectrum due to this increase in the microwave photons via the Compton scattering from high-energy electrons.

Hard X-ray observations of the Crab Nebula and A0535+26 with a high energy resolution spectrometer

1983 ◽  
Vol 270 ◽  
pp. 144 ◽  
Author(s):  
J. M. Hameury ◽  
D. Boclet ◽  
Ph. Durouchoux ◽  
T. L. Cline ◽  
B. J. Teegarden ◽  
...  
Keyword(s):  
Energy Resolution ◽  
Crab Nebula ◽  
High Energy ◽  
High Energy Resolution ◽  
X Ray ◽  
The Crab Nebula ◽  
Resolution Spectrometer
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