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arXiv · 1101.2499

An Improved Dynamical Model for the Microquasar XTE J1550-564

Jerome A. Orosz·James F. Steiner·Jeffrey E. McClintock·Manuel A. P. Torres·Ronald A. Remillard·Charles D. Bailyn·Jon M. Miller
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Abstract

We present an improved dynamical model of the X-ray binary and microquasar XTE J1550-564 based on new moderate-resolution optical spectroscopy and near-infrared photometry. By combining our new radial velocity measurements with previous measurements obtained 2001 May at the 8.2m VLT and with light curves, we find an orbital period of P=1.5420333 +/- 0.0000024 days and a radial velocity semiamplitude of K_2=363.14 +/- 5.97$ km/sec, which together imply an optical mass function of f(M)=7.65 +/- 0.38 solar masses. We find that the projected rotational velocity of the secondary star is 55 +/- 5 km/sec, which implies a very extreme mass ratio of Q=M/M_2=30. Using a model of a Roche lobe-filling star and an azimuthally symmetric accretion disk, we fit simultaneously optical light curves from 2001, near-infrared light curves from 2008 and all of the radial velocity measurements to derive system parameters. We find an inclination of 74.7 +/- 3.8 deg and component masses of M_2=0.30 +/- 0.07 solar masses and M=9.10 +/- 0.61 solar masses for the secondary star and black hole, respectively. The radius of the secondary star for the adopted model is 1.75 +/- 0.12 solar radii. Using this radius, the average K_S magnitude, and an extinction of A_K=0.507 +/- 0.050 mag, we find a distance of 4.38^{+0.58}_{-0.41} kpc, which is in good agreement with a recent distance estimate based on HI absorption lines (abstract shortened).

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Jerome A. Orosz, James F. Steiner, Jeffrey E. McClintock, Manuel A. P. Torres, Ronald A. Remillard, Charles D. Bailyn, Jon M. Miller. 2011-01-13. An Improved Dynamical Model for the Microquasar XTE J1550-564. https://doi.org/10.1088/0004-637x%2F730%2F2%2F75

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