X-ray Binary Cygnus Research Articles

Infrared spectroscopic variability of Cygnus X-3

We present four epochs of high-resolution IR spectroscopy of the peculiar X-ray binary Cygnus X-3. The observations cover quiescent, small flaring and outburst states of the system as defined by radio and X-ray monitoring. The underlying IR spectrum of the source, as observed during radio and X-ray quiescence and small flaring states is one of broad, weak He II and N V emission. Spectral variability in this state is dominated by modulation at the 4.8 hr orbital period of the system. H-band spectra confirm the significant hydrogen depletion of the mass donor. In outburst, the infrared spectrum is dramatically different, with the appearance of very strong twin-peaked He I emission displaying both day-to-day variability and V (iolet) / R(ed) variations with orbital phase. We argue that the most likely explanation appears to be an enhanced stellar wind from the companion. Thus the X-ray and radio outbursts in this system are likely to originate in mass-transfer, and not disc instabilities. We suggest that the wind in Cyg X-3 is significantly flattened in the plane of the binary orbit. This may explain the observed twin-peaked He I features as well as reconcile the large infrared luminosity with the large optical depth to X-rays if Cyg X-3 is embedded in a spherically symmetric wind.

Discovery of Correlated Behavior between the Hard X‐Ray and the Radio Bands in Cygnus X‐3

Using CGRO/BATSE hard X-ray data and GHz radio monitoring data from the Green Bank Interferometer (GBI), we have performed a long term study (approximately 1800 days) of the unusual X-ray binary Cygnus X-3 resulting in the discovery of a remarkable relationship between the two wavelength bands. We find that quiescent radio states are strongly anticorrelated with the intensity of the hard X-ray emission. With the onset of a flaring state the relationship switches to a correlation. This is most easily seen in the larger (> or = 1 Jy) flares where the preflare quenched radio emission is accompanied by a very low hard X-ray intensity, and recovery of the hard X-ray flux during the radio flare. The injection of plasma into the radio jets, associated with Cyg X-3, can be directly related to changes in the hard X-ray emission, and suggests the possibility of accretion-related and jet-related components of the high energy emission.

Apparent superluminal expansion in Cygnus X-3

The Galactic radio-emitting X-ray binary Cygnus X-3 is known to be a source of large-scale radio jets associated with periods of intense radio flaring. These jets have been found to have an expansion velocity of ∼0.3c and are believed (on kinematic grounds) to lie close to the plane of the sky. We present new observations of Cygnus X-3 using the VLBA at 15 GHz. These observations, which included the detection of two small flares, show an additional kind of behaviour with apparent superluminal expansion along both major and minor axes. Evidence for superluminal activity has been found in a number of X-ray binary systems such as GRS 1915+105 and GRO J1655−40 with their superluminal radio jets. Apparently similar morphologies of the Galactic and extragalactic jet sources have led to the X-ray binaries being described as ‘micro-quasars’. The superluminal expansion seen in our results appears to be different in nature from these other two sources, and a number of mechanisms are presented and discussed.

Infrared Emission Around Cyg X-3

AbstractWe present UKIRT infrared images of the X-ray binary Cygnus X-3. We address the possibility of extended infrared emission and show that it could be either warm circumstellar material or a star near the binary’s line of sight.

The evolution of outbursts in Cygnus X-3

Quenching of the X-ray binary Cygnus X-3 at 2.25 GHz prior to outbursts during 1990–1993 is compared with published multi-frequency results. Flux density measurements obtained at 15 GHz with the Ryle Telescope during 1994–1995 are compared with flux densities at 2.25 GHz obtained with the NRL Green Bank Interferometer. Quenched quiescent emission prior to outbursts and partially quenched emission during small flaring episodes may be explained by disk instabilities during super-Eddington and near-Eddington accretion in X-ray binaries.

Photoionization-Driven X-Ray Line Emission in Cygnus X-3

The ASCA SIS spectrum of the X-ray binary Cygnus X-3 is shown to contain a narrow recombination continuum of hydrogenic sulfur near 3.5 keV, which indicates that the temperature of the X-ray emission-line region is far below the coronal equilibrium temperature required to support S15+. The presence of this feature immediately confirms that X-ray photoionization produces extreme overionization in the circumsource medium, and that the X-ray emission features are energized by the hard X-ray continuum. Therefore, we conclude that spectral analyses of Cygnus X-3 and, most likely, other accretion-powered X-ray sources must be conducted in the context of plasma emission models that account for population kinetics dominated by recombination. Furthermore, the temperature dependence of the shapes of recombination continua provides a simple diagnostic of the electron temperature. We reanalyze the SIS data using a spectral model developed to account for recombination cascades, and, using these diagnostics, derive constraints on the temperatures in the S15+, Si13+, and Mg11+ ionization zones.

The Evolution of Outbursts in Cygnus X-3 at 2.25 and 8.3 GHz

view Abstract Citations (60) References (19) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Evolution of Outbursts in Cygnus X-3 at 2.25 and 8.3 GHz Waltman, E. B. ; Ghigo, F. D. ; Johnston, K. J. ; Foster, R. S. ; Fiedler, R. L. ; Spencer, J. H. Abstract Detailed observations of a long outburst in the X-ray binary Cygnus X-3 at 2.25 and 8.3 GHz in early 1994 are presented. The source has been monitored at dual radio frequencies on a daily basis with the Green Bank Interferometer since 1982. This outburst was predicted based on the behavior of the quiescent flux densities prior to the major flare. The data show that the 1994 February 20 flare occurred just one day after 19 days of very low quiescent flux densities and exhibited higher opacity at 2 GHz than usual for Cygnus X-3 flares. Later flares in the 1994 February-March outburst sequence displayed progressively less opacity as determined from the observed ratios of peak flux densities at the two frequencies, the lags between the peaks, and the spectral index. Examination of the evolution of spectral index during the 1994 February outburst, compared to previous outbursts in the history of Cygnus X-3, shows that the trend toward optically thin flares begins with the onset of outburst activity immediately following the very low quiescent flux densities and may relate to the very low flux densities. This behavior can be interpreted either as evidence for a declining opacity from thermal gas in the binary system or for evolution of the exponential lateral expansion rate of the jet during the series of flares in the outburst. Publication: The Astronomical Journal Pub Date: July 1995 DOI: 10.1086/117518 Bibcode: 1995AJ....110..290W Keywords: BINARIES: CLOSE; X-RAYS: STARS full text sources ADS |

Diffusive shock acceleration in the presence of a strong ambient magnetic field

By an appeal to the microscopic approach of the process, a framework is developed which can take into account arbitrary energy dependence of the diffusion coefficient and an arbitrary ratio of the ambient magnetic field strengths in the upstream and downstream region within the approximation of a plane shock. There are significant departures from the results obtained by earlier authors. In particular, the problem of particle acceleration by an accretion shock in the X-ray binary Cygnus X-3 is treated. 18 refs.

Underground search for muons correlated with Cygnus X-3.

We have examined muon data collected with the IMB (Irvine-Michigan-Brookhaven) proton-decay detector in search of a muon flux associated with the x-ray binary Cygnus X-3. A sample of 3.6×104 muons from the direction of Cygnus X-3 during the period September 1982 until April 1984 shows no evidence of its characteristic 4.8-h periodicity. In the phase interval 0.65 to 0.90 where a signal has been reported by other workers at a similar depth we obtain a 90%-confidence-level limit to the flux of 6.9×10−11 cm−2sec−1 for a depth of 1800 m water equivalent. This limit does not conflict with the reported signal. Three subsets of the data taken during Cygnus X-3 radio bursts have been separately analyzed. We find some evidence for an excess in the phase interval 0.50–0.60 at the time of the October 1983 outburst. We examine this excess in detail.Received 8 December 1986DOI:https://doi.org/10.1103/PhysRevD.36.30©1987 American Physical Society

A 12.6-ms pulsar in Cygnus X-3

The X-ray binary Cygnus X-3 has long been suspected of containing a fast, young pulsar, but previous observations at various wavelengths have failed to provide any evidence of a signal with a periodicity of less than 4.8 h (the well-known periodicity in the X-ray and infrared wavebands which is ascribed to orbital motion of a binary system). Here we report measurements of 1,000-GeV γ-rays which suggest a pulsar period of 12.5908±0.0003 ms, for data recorded in 1983 at the times of X-ray maximum in the 4.8-h cycle. The conservative probability of such a periodicity occurring by chance is 4 × 10−7 and, moreover, supportive evidence is provided by some earlier data.

Cosmic-ray emission from Cygnus X-3

Recent observations1,2 of the X-ray binary source Cygnus X-3 have revealed a flux of ultra-high energy γ rays. Other observations and subsequent models suggest that Cyg X-3 may be a dominant source of galactic high-energy cosmic rays. Here I investigate whether it is possible to escape this conclusion with a model in which most of the energy of accelerated particles at the source is emitted as curvature radiation (that is, radiation emitted by particles travelling on curved paths in a magnetic field so strong that synchrotron radiation is suppressed). I conclude that such a model is not consistent with the observations.