A refined dynamical mass for the black hole in the X-ray transient XTE J1859+226

Abstract

We present two contiguous nights of simultaneous time-resolved GTC spectroscopy and WHT photometry of the black hole X-ray transient XTE J1859+226, obtained in 2017 July during quiescence. Cross-correlation of the individual spectra against a late K-type spectral template enabled us to constrain the orbital period to $0.276\pm 0.003$ d and the radial velocity semi-amplitude of the donor star to $K_2=550\pm 59$ km s${}^{-1}$. An ellipsoidal modulation is detected in the photometric $r$- and $i$-band light curves, although it is strongly contaminated by flickering activity. By exploiting correlations between the properties of the double-peaked H$\alpha$ emission-line profile and the binary parameters, we derived an orbital inclination of $66.6\pm 4.3$ deg, a refined $K_2=562\pm 40$ km s${}^{-1}$ and mass ratio $q=M_2/M_1=0.07\pm 0.01$. From these values we obtained an updated black hole mass of $M_1=7.8\pm 1.9$ M${}_{\odot }$. An independent mass estimate based on X-ray timing agrees well with our value, which gives further support for the outburst QPO triplet being explained by the relativistic precession model. We also obtained a companion star mass $M_2=0.55\pm 0.16$ M${}_{\odot }$, which is consistent with its K5-K7 V spectral type.

7 pages, 5 figures

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Cited by in corpus (6)

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• Spin precession frequencies of a test gyroscope around a naked singularity and quasi-periodic oscillations
• Timing of accreting neutron stars with future X-ray instruments: towards new constraints on dense matter equation of state
• An infrared FWHM-$K_2$ correlation to uncover highly reddened quiescent black holes
• Empirical correlation between masses of black holes and Wolf-Rayet stars derived from their mass distributions in spectroscopic binaries
• X-ray Quasi-Periodic Oscillations in Active Galactic Nuclei and Their Implications for the Changing Look Phenomenon