Constraining System Parameters of Eclipsing X-ray Binaries with the Swift Burst Alert Telescope (BAT)
Abstract
Physical parameters of both the mass donor and compact object are constrained in X-ray Binaries with well defined eclipses. The eclipse duration depends on the radius of the mass donor, inclination angle of the system, and the orbital separation of the components. Using the observed orbital period and Kepler's third law, the orbital separation can be written in terms of the sum of the component masses. This stipulates that the eclipse half-angle can now be expressed in terms of the radius, inclination angle and the sum of the masses. When pulse-timing and radial velocity curves are available, the masses of both the donor and compact object can be accurately determined. We present a survey of the Eclipsing X-ray Binaries IGR J16393-4643, IGR J16418-4532, IGR J16479-4514, IGR J18027-2016 and XTE 1855-026. To determine the eclipse half-angle in our survey, we modeled the eclipses using a symmetric step-and-ramp function. The eclipse half-angle was found to be 15±3, 29±1, 32±1, 32±1 and 34.3±0.6 degrees for IGR J16393-4643, IGR J16418-4532, IGR J16479-4514, IGR J18027-2016 and XTE 1855-026, respectively. This is consistent with the proposed mass donors for each binary. We place constraints on the inclination angle of the system and radius and mass of the donor star.
- Publication:
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AAS/High Energy Astrophysics Division #14
- Pub Date:
- August 2014
- Bibcode:
- 2014HEAD...1412208C