On the physical reality of the millisecond bursts in Cygnus X-1 - Bursts and shot noise

Weisskopf, M. C.; Sutherland, P. G.

doi:10.1086/156022

Cited by 12 publications

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“…It also closely corresponds to the e‐folding time of the 1999 flare of Sgr A* (Baganoff et al 2001) of ∼400 s, which is ∼30 GM / c 3 for a 3 × 10 6 M ⊙ black hole. Although variability on ms time‐scales in Cyg X‐1 was reported from early experiments (Rothschild et al 1974, 1977; Boldt 1977; Meekins et al 1984), its reality was questioned (Press & Schechter 1974; Weisskopf & Sutherland 1978; Chaput et al 2000). Also, no power on time‐scales <2 ms has been detected in the PCA data for Cyg X‐1 (Revnivtsev, Gilfanov & Churazov 2000), which appears to be generally the case for black hole binaries (Sunyaev & Revnivtsev 2000).…”

Section: Introductionmentioning

confidence: 99%

Discovery of powerful millisecond flares from Cygnus X-1

Zdziarski¹

2003

Monthly Notices of the Royal Astronomical Society

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We have found a large number of very strong flares in the available XTE PCA data of Cyg X-1 (also seen in available HEXTE and BATSE data) with 13 flares satisfying our chosen threshold criterion, occuring both in the hard and the soft states. We analyze here in detail two of them. The strongest one took place in the soft state, with the 3-30 keV energy flux increasing 30 times with respect to the preceding 16-s average. The e-folding time is ~ 7 ms for the main flare and ~ 1 ms for its precursor. The spectrum strongly hardens during the flare. On the other hand, flares in the hard state have generally lower amplitudes and longer e-folding times, and their spectra soften during the flare, with the hardness of the spectrum at the flare peak similar for both types of the flares. The presence of the flares shows unusually dramatic events taking place in the accretion flow of Cyg X-1. On the other hand, the rate of occurence of hard-state flares shows they may represent a high-flux end of the distribution of shots present in usual lightcurves of Cyg X-1.Comment: Accepted for publication in MNRA

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Section: Introductionmentioning

confidence: 99%

Discovery of powerful millisecond flares from Cygnus X-1

Zdziarski¹

2003

Monthly Notices of the Royal Astronomical Society

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“…A pheno menological model, capable of explaining all these features, can be found in a random shot-noise process as originally suggested by Terrell (1972). In this model the mentioned i msec "burst s" would not be intrinsic to the source, since they are explained as mere statistical fluctuations enhanced by the non poissonian character of the process (Weisskopf et al, 1978). Estimates of the parameters of the shot-noise process have been performed by means of autocorrelation studies and the use of the third moment (e.g.…”

Section: Introductionmentioning

confidence: 91%

Power spectral density analysis of hard X-ray emission of Cyg X-1

Frontera¹,

Fuligni²

1981

Space Sci Rev

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We report on results of analysis'performed on data of three balloon observations of C~rg X-I in the range 20-200 keV. Evidence of periodic, even if not stable, pulsationswere previously obtained at about 0.058 Hz. The continuous power spectrum, still showing a broad peak around the above frequency, can be explained on the basis of a model, similar to the shot noise one, where the single shot is replaced by a short sequence of equispaced pulses with a decaying amplitude. Such a model could also explain the burshinu activity observed at lower energies.

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Variability in accreting black holes

Fabian

The Physics of Accretion Onto Compact Objects

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On the physical reality of the millisecond bursts in Cygnus X-1 - Bursts and shot noise

Cited by 12 publications

References 0 publications

Discovery of powerful millisecond flares from Cygnus X-1

Discovery of powerful millisecond flares from Cygnus X-1

Power spectral density analysis of hard X-ray emission of Cyg X-1

Variability in accreting black holes

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