2002ApJ...568..845O -
Astrophys. J., 568, 845-861 (2002/April-1)
Dynamical evidence for a black hole in the microquasar XTE J1550-564.
OROSZ J.A., GROOT P.J., VAN DER KLIS M., McCLINTOCK J.E., GARCIA M.R., ZHAO P., JAIN R.K., BAILYN C.D. and REMILLARD R.A.
Abstract (from CDS):
Optical spectroscopic observations of the companion star (type G8 IV to K4 III) in the microquasar system XTE J1550-564 reveal a radial velocity curve with a best-fitting spectroscopic period of Psp=1.552±0.010 days and a semiamplitude of K2=349±12 km.s–1. The optical mass function is f(M)=6.86±0.71M☉ (1 σ). We tentatively measure the rotational velocity of the companion star to be Vrotsini=90±10 km.s–1, which when taken at face value implies a mass ratio of Q≡M1/M2=6.6+2.5–1.6 (1 σ), using the above value of K2. We derive constraints on the binary parameters from simultaneous modeling of the ellipsoidal light and radial velocity curves. We find 1 σ ranges for the photometric period (1.5430days≤Pph≤1.5440days), K-velocity (350.2≤K2≤368.6 km.s–1), inclination (67°.0≤i≤77°.4), mass ratio (Q≥12.0), and orbital separation (11.55R☉≤a≤12.50R☉). Given these geometrical constraints, we find that the most likely value of the mass of the compact object is 9.41 M☉ with a 1 σ range of 8.36M☉≤M1≤10.76M☉. If we apply our tentative value of Vrotsini=90±10 km.s–1 as an additional constraint in the ellipsoidal modeling, we find 1 σ ranges of 1.5432days≤Pph≤1.5441days for the photometric period, 352.2≤K2≤370.1 km.s–1 for the K-velocity, 70°.8≤i≤75°.4 for the inclination, 6.7≤Q≤11.0 for the mass ratio, and 12.35R☉≤a≤13.22R☉ for the orbital separation. These geometrical constraints imply the most likely value of the mass of the compact object of 10.56 M☉ with a 1 σ range of 9.68M☉≤M1≤11.58M☉. In either case the mass of the compact object is well above the maximum mass of a stable neutron star, and we therefore conclude that XTE J1550-564 contains a black hole.
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Journal keyword(s):
Stars: Binaries: Spectroscopic - Black Hole Physics - Stars: Individual: Alphanumeric: XTE J1550-564 - X-Rays: Binaries - X-Rays: Stars
Simbad objects:
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