X-ray observations of Cyg X-1 with ANS

Heise, J.; Mewe, R.; Brinkman, A. C.; Boggende, A. den; Schrijver, Carolus J.; Gronenschild, E. H. B. M.; Parsignault, D. R.; Grindlay, Jonathan E.; Schreier, E.; Schnopper, H. W.

doi:10.1038/256107a0

Cited by 22 publications

(11 citation statements)

References 4 publications

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“…A large average linear polarization of HDE226868 has been reported (Hiltner, 1956;Gehreis, 1972;Coyne et al, 1974). It is presumably due to the interstellar dusts and is consistent with the estimated distance of -2 kpc.…”

Section: Polarizationmentioning

confidence: 87%

“…Small amplitude light variations with the 5.6-day binary period were discovered in 1972 (Cherepashchuk et al, 1973;Walker, 1972;Lester et al, 1973) and further studies have been carried out by several groups (Hilditch and Hill, 1974;Walker and Quintanilla, 1974). The results by Walker are shown in Figure 2-4.…”

Section: Light Variationsmentioning

confidence: 94%

“…The spectral type of the star may vary with phase of the binary from about O9.5 to B0; various authors have given somewhat different classifications within the indicated range. The apparent magnitude and colors of the star are V=8.87, B-V= 0.81, and U-B =-0.30 (Hiltner, 1956). …”

Section: Classificationmentioning

confidence: 98%

“…Figure 1-1 summarizes the results of the observations. The determined location led to the discovery of a radio source by Braes and Miley (1971) and Hjellming and Wade (1971). This radio source was Fig.…”

mentioning

confidence: 97%

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CygX-1/A candidate of the black hole

Oda

1977

Space Sci Rev

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Abstract. Among discrete galactic X-ray sources, Cyg X-1 has been noted for its peculiar features in several respects. It is one of the few sources with a hard power law spectrum extending beyond several hundred keV. Cyg X-1 also distinguishes itself by its profound time variability over a wide range of time scales. The most remarkable incident was that its optical identification with a spectroscopic binary HDE226868 has led to a presumption that it is a black hole. This possibility has induced continuous interests in the physical character of this source in conjunction with the nature of the black hole. The purpose of this paper is to summarize presently available pieces of knowledge on this source to help the design of future experimental and theoretical works, while the complexity of the source characteristics still has prevented us to construct a clear, coherent picture of this source in spite of the fact that numerous observational facts have been accumulated. Contents:

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Section: Polarizationmentioning

confidence: 87%

Section: Light Variationsmentioning

confidence: 94%

Section: Classificationmentioning

confidence: 98%

mentioning

confidence: 97%

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CygX-1/A candidate of the black hole

Oda

1977

Space Sci Rev

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“…The first GBH candidate, Cygnus X-1, was discovered by a rocket experiment in the 1960s [1]. Balloon-borne experiments led to characterizations of its spectral shape [2,3], while space-based experiments discovered its flux state transitions [4,5,6], and later, its spectral state transitions [7]. Early gamma-ray observations showed that Cygnus X-1 is variable at higher energies [8,9,10], with episodic emission observed up to > 1 MeV [11,12].…”

Section: Introductionmentioning

confidence: 99%

Low Energy Gamma-Ray Emission from Galactic Black Holes

Case¹,

Cherry²,

Ling³

et al. 2008

AIP Conference Proceedings

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Abstract. X-ray observations of Galactic black holes (GBHs) such as Cygnus X-1 have greatly advanced the understanding of these objects. However, the vast majority of the observations have been restricted to energies below ∼ 200 keV. The Compton Gamma-Ray Observatory (CGRO) allowed for the first time simultaneous observations at energies from ∼ 25 keV up to > 1 GeV. In particular, the BATSE experiment aboard CGRO was able to monitor low-energy gamma-ray emission from Cygnus X-1, as well as other GBHs, nearly continuously over a nine year period. Using the Enhanced BATSE Occultation Package (EBOP), light curves and spectra in the energy range 25 − 2000 keV have been obtained for six GBHs. Based on the spectra when the GBHs were in a high gamma-ray flux state, it is suggested that at least two different classes of GBHs exist. The first is characterized by a Comptonization spectrum below ∼ 200 keV followed by a soft power law excess as exhibited by Cygnus X-1, GRO J0422+32, GRO J1719-24, and GX 339-4. The second class is characterized by simple power law spectrum in the full 25 − 2000 keV range, with no evidence for a Comptonization component, as exhibited by GRO J1655-40 and GRS 1915+105.Gamma-ray observations can serve as an important diagnostic in studying the physical processes around GBHs. More sensitive observations in the future at energies > 250 keV will help answer questions regarding issues such as the nonthermal electron distribution, state transitions, and the connection to jets.

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Celestial binary X-ray sources

Apparao

Chitre

1976

Space Sci Rev

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X-ray observations of Cyg X-1 with ANS

Cited by 22 publications

References 4 publications

CygX-1/A candidate of the black hole

CygX-1/A candidate of the black hole

Low Energy Gamma-Ray Emission from Galactic Black Holes

Celestial binary X-ray sources

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