A Multi-Wavelength Study of the Relativistic Jet Source Cygnus X-3
Dr. Michael L. McCollough
Cygnus X-3 is one of the most enigmatic X-ray binaries to have been studied. Its
X-ray flux shows a 4.79 hr modulation associated with its orbital period. While
the period is typical of a low mass system IR observations have shown that the
mass donating companion is a massive Wolf-Rayet star. Cygnus X-3 has two
major X-ray states (low/hard and high/soft), shows correlative activity between
the radio and hard X-ray, and relativistic jets have been observed in the
Among the issues we are seeking to address in this study are:
Hard X-Ray/Gamma-Ray Continuum: We seek to understand the
nature of the hard X-ray/gamma-Ray continuum associated with major radio flares.
Is it due to synchrotron or inverse Compton? Are the processes producing this
emission nonthermal or thermal in nature?
Annihilation Lines: The major radio flares in Cygnus X-3
have been linked to relativistic jets. The composition of these jets is a major
point of interest. Are they a pair plasma (electrons and positrons) or do
baryons play major role in their makeup? The detection of annihilation lines
make help answer this question.
Timing Properties: Do the major flares have a distinctive
timing signature? The RXTE observations probe times very close to the
creation of these major flares.
Properties of Cygnus X-3's Wind: The Chandra observations
(supported by the RXTE) observations will allow a detailed (phased resolved)
measurement of the parameters and nature of the wind associated with
Multi-Wavelength Correlations: We will look for and study the
correlations between the different wavelenghts (radio, X-ray, Gamma-Ray, IR).
These will be examined relative to previously discovered correlations.
Since early 2002 Cygnus X-3 had been in an unusually long quiescent state
(~ 1300 days). At the start of 2006 Cygnus X-3 transitioned from a radio
quiescent (low/hard) state to a flaring (high/soft) state. Among the
activities that have been observed are an extended quenched state (high X-ray,
very low radio, and very low hard X-ray emission), rapid (< 1 day) bright
flares (~ 3 Jy), and three major radio flares (~ 14 Jy).
During this active state, a major international multi-wavelength observing
campaign has been undertaken. This campaign includes observations in the radio
(Ryle, RATAN-600), IR (PAIRITEL), UV/Optical (Swift), X-ray (Chandra, RXTE,
INTEGRAL, Swift), hard X-ray (RXTE, INTEGRAL, Swift), and Gamma-ray (INTEGRAL,
This project involves the analysis of these various data sets with particular
emphasis on the spacecraft data (Chandra, INTEGRAL, RXTE, and Swift). We will
be using XSPEC, FTOOLS, CIAO, and OSA (INTEGRAL Data Analysis) software to
analyze the various data sets.
Other links related to this project