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

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.

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Hard Cosmic X-Ray Sources

Symposium - International Astronomical Union ◽

10.1017/s0074180900100270 ◽

1973 ◽

Vol 55 ◽

pp. 51-73 ◽

Cited By ~ 1

Author(s):

L. E. Peterson

Keyword(s):

Supernova Remnants ◽

Galactic Center ◽

Galactic Plane ◽

Crab Nebula ◽

X Rays ◽

X Ray ◽

Sky Survey ◽

Upper Limits ◽

Observational Status ◽

The Crab Nebula

A review of the observational status of X-ray sources detected in the 20 ⋍ 500 keV range is presented. Of the approximately 115 sources listed in the March 1972 edition of the UHURU 2–6 keV sky survey catalog, about 15 sources have been studied in hard X-rays. Most of the data have been obtained from balloons, although the OSO-3, and more recently the OSO-7, have contributed. With the exception of CEN A, the SMC, and possibly M-87, all the sources detected at higher energies are galactic and heavily concentrated in the galactic plane. The Crab Nebula has been measured to about 500 keV in continuous emission and a component at the ⋍ 33 ms pulsar period comprising about 20% of the total emission has been detected to ∼10 MeV. Objects such as SCO-1 and CYG-2 are characterized by an exponential spectrum, which varies over a 10 min. time scale about a factor of two, and a flatter spectrum extending to above 40 keV which exhibits independent variability. Objects such as CYG-1 and possibly CYG-3 have a multi-component power law spectrum extending to over 100 keV, and may vary many factors over a period of weeks. Other sources generally not yet identified with optical or radio candidates, located in the Galactic Center and the Centaurus/Crux region also show considerable variability, and in one case may have been detected to nearly 500 keV. Only upper limits at about 2 × 10−4 photon (cm2 s keV)−1 in the 20–50 keV range exist for most supernova remnants and extragalactic sources.

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Sky Survey of High-Energy Cosmic X-Rays and Spectra of the Sources in the Crab Nebula and Cygnus

The Astrophysical Journal ◽

10.1086/149415 ◽

1968 ◽

Vol 151 ◽

pp. 21 ◽

Cited By ~ 23

Author(s):

G. W. Clark ◽

W. H. G. Lewin ◽

W. B. Smith

Keyword(s):

Crab Nebula ◽

High Energy ◽

X Rays ◽

Sky Survey ◽

The Crab Nebula

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Properties of individual X-ray sources: (Invited discourse)

Symposium - International Astronomical Union ◽

10.1017/s0074180900004034 ◽

1970 ◽

Vol 37 ◽

pp. 59-80

Author(s):

Laurence E. Peterson

Keyword(s):

Power Law ◽

Crab Nebula ◽

Optical Observations ◽

X Rays ◽

X Ray ◽

Upper Limits ◽

Time Variations ◽

Γ Rays ◽

The Crab Nebula

Observations to determine the spectra and time variations of hard X-rays from cosmic sources have been made from balloons and from the OSO-III satellite. These data have been obtained using actively collimated scintillation counters with apertures between 6 and 24° FWHM, areas between 10 and 50 cm2 and which operate over the 10–300 keV range. The Crab Nebula has been observed on three occasions over a 22-month period between September 1965 and July 1967. The power law spectrum has a number index of 2.0 ± 0.1. No long-term changes were observed over the 30–100 keV range with a limit at 3%/yr. A balloon search with a 10 cm2 Ge(Li) detector for X-ray lines at 62.5 keV, 110 keV and 180 keV due to heavy element radioactive decays which would be produced in the initial Crab explosion based on the Cf254 hypothesis has resulted in upper limits at about 10−3 γ-rays cm2-sec. This is about a factor of 20 above the predicted levels. Simultaneous X-ray and optical observations of SCO XR-1 from OSO-III confirm that X-ray and optical flaring are indeed coincident phenomena, and that although the X-ray intensity increases about a factor of two during the flare, the equivalent temperature of the excess radiation is nearly the same as that of the quiescent object. Upper limits, 95% confidence, on the flux of M-87 at 40 keV have been obtained. These are inconsistent with the flux of 1.2 × 10−4 photons/cm2-sec-keV reported in the literature. CYG X-1 has been observed to have a power law of number index 2.0 ± 0.2. The OSO-III has observed a number of sources in the southern skies including NOR XR-2 and the variable source Centaurus XR-2.

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Time-Domain Astronomy with Swift, Fermi and Lobster

Proceedings of the International Astronomical Union ◽

10.1017/s174392131200018x ◽

2011 ◽

Vol 7 (S285) ◽

pp. 41-46 ◽

Cited By ~ 2

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.

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Low-energy cosmic X-ray measurements

Canadian Journal of Physics ◽

10.1139/p69-324 ◽

1969 ◽

Vol 47 (23) ◽

pp. 2651-2666 ◽

Cited By ~ 14

Author(s):

A. J. Baxter ◽

B. G. Wilson ◽

D. W. Green

Keyword(s):

Spectral Analysis ◽

Energy Range ◽

Crab Nebula ◽

Spectral Characteristics ◽

Low Energy ◽

Data Recovery ◽

X Rays ◽

X Ray ◽

Recovery System ◽

The Crab Nebula

An experiment is described to investigate cosmic X rays in the energy range 0.25–12 keV. The data-recovery system and methods of spectral analysis are considered. Results are presented for the energy spectrum of the diffuse X-ray component and its distribution over the northern sky down to 1.6 keV with a limited extension at 0.27 keV.In the energy range 1.6 to 12 keV, the spectrum is represented by:[Formula: see text]although separate analyses indicate a flattening below 4.5 keV to give:[Formula: see text]and[Formula: see text]At the lowest energies, the flux appears to increase more rapidly and exhibits some anisotropy in arrival directions related to the gross galactic structure. Spectral characteristics of the Crab Nebula and Cygnus X-2 have also been determined.

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High-energy X rays from the Crab Nebula

Journal of Geophysical Research Atmospheres ◽

10.1029/jz071i013p03261 ◽

1966 ◽

Vol 71 (13) ◽

pp. 3261-3264 ◽

Cited By ~ 7

Author(s):

R. C. Haymes ◽

W. L. Craddock

Keyword(s):

Crab Nebula ◽

High Energy ◽

X Rays ◽

The Crab Nebula

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High energy cosmic photons and neutrinos

Symposium - International Astronomical Union ◽

10.1017/s0074180900179628 ◽

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.

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The electromagnetic spectrum of the Crab Nebula

Symposium - International Astronomical Union ◽

10.1017/s0074180900004368 ◽

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.

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