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arXiv · 2209.10395

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

I. V. Yanes Rizo·M. A. P. Torres·J. Casares·S. E. Motta·T. Muñoz-Darias·P. Rodríguez-Gil·M. Armas Padilla·F. Jiménez-Ibarra·P. G. Jonker·J. Corral-Santana·R. Fender
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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$α$ 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.

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I. V. Yanes Rizo, M. A. P. Torres, J. Casares, S. E. Motta, T. Muñoz-Darias, P. Rodríguez-Gil, M. Armas Padilla, F. Jiménez-Ibarra, P. G. Jonker, J. Corral-Santana, R. Fender. 2022-09-21. A refined dynamical mass for the black hole in the X-ray transient XTE J1859+226. https://doi.org/10.1093/mnras%2Fstac2719

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