On the distance to the black hole X-ray binary Swift J1727.8$-$1613
Benjamin J. Burridge (International Centre for Radio Astronomy Research, Curtin University, Perth, Australia), James C. A. Miller-Jones (International Centre for Radio Astronomy Research, Curtin University, Perth, Australia), Arash Bahramian (International Centre for Radio Astronomy Research, Curtin University, Perth, Australia), Steve R. Prabu (International Centre for Radio Astronomy Research, Curtin University, Perth, Australia), Reagan Streeter (International Centre for Radio Astronomy Research, Curtin University, Perth, Australia), Noel Castro Segura (Department of Physics, University of Warwick, Coventry, UK), Jes’us M. Corral Santana (European Southern Observatory, Santiago, Chile), Christian Knigge (School of Physics & Astronomy, University of Southampton, Southampton, UK), Andrzej Zdziarski (Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Warszawa, Poland), Daniel Mata S’anchez (Instituto de Astrof’isica de Canarias, Tenerife, Spain), Evangelia Tremou (National Radio Astronomy Observatory, Socorro, USA), Francesco Carotenuto (INAF-Osservatorio Astronomico di Roma, Monte Porzio Catone, Italy), Rob Fender (Astrophysics, Department of Physics, University of Oxford, Oxford, UK), Payaswini Saikia (Center for Astrophysics and Space Science, New York University Abu Dhabi, Abu Dhabi, UAE)
arXiv:2502.06448v2 Announce Type: replace
Abstract: We review the existing distance estimates to the black hole X-ray binary Swift J1727.8$-$1613, present new radio and near-UV spectra to update the distance constraints, and discuss the accuracies and caveats of the associated methodologies. We use line-of-sight HI absorption spectra captured using the MeerKAT radio telescope to estimate a maximum radial velocity with respect to the local standard of rest of $24.8 pm 2.8 , {rm km,s^{-1}}$ for Swift J1727.8$-$1613, which is significantly lower than that of a nearby extragalactic reference source. From this we derive a near kinematic distance of $d_{rm near} = 3.6 pm 0.3 , ({stat}) pm 2.3 , ({sys}) , {rm kpc}$ as a lower bound after accounting for additional uncertainties given its Galactic longitude and latitude, $(l, b) approx (8.6^{circ}, 10.3^{circ})$. Near-UV spectra from the Hubble Space Telescope’s Space Telescope Imaging Spectrograph allows us to constrain the line-of-sight colour excess to $E(B!-!V) = 0.37 pm 0.01 , ({stat}) pm 0.025 , ({sys})$. We then implement this in Monte Carlo simulations and present a distance to Swift J1727.8$-$1613 of $5.5^{+1.4}_{-1.1} , {rm kpc}$, under the assumption that the donor star is an unevolved, main sequence K3-5V star. This distance implies a natal kick velocity of $190 pm 30 , {rm km,s^{-1}}$ and therefore an asymmetrical supernova explosion within the Galactic disk as the expected birth mechanism. A lower distance is implied if the donor star has instead lost significant mass during the binary evolution. Hence, more accurate measurements of the binary inclination angle or donor star rotational broadening from future observations would help to better constrain the distance.arXiv:2502.06448v2 Announce Type: replace
Abstract: We review the existing distance estimates to the black hole X-ray binary Swift J1727.8$-$1613, present new radio and near-UV spectra to update the distance constraints, and discuss the accuracies and caveats of the associated methodologies. We use line-of-sight HI absorption spectra captured using the MeerKAT radio telescope to estimate a maximum radial velocity with respect to the local standard of rest of $24.8 pm 2.8 , {rm km,s^{-1}}$ for Swift J1727.8$-$1613, which is significantly lower than that of a nearby extragalactic reference source. From this we derive a near kinematic distance of $d_{rm near} = 3.6 pm 0.3 , ({stat}) pm 2.3 , ({sys}) , {rm kpc}$ as a lower bound after accounting for additional uncertainties given its Galactic longitude and latitude, $(l, b) approx (8.6^{circ}, 10.3^{circ})$. Near-UV spectra from the Hubble Space Telescope’s Space Telescope Imaging Spectrograph allows us to constrain the line-of-sight colour excess to $E(B!-!V) = 0.37 pm 0.01 , ({stat}) pm 0.025 , ({sys})$. We then implement this in Monte Carlo simulations and present a distance to Swift J1727.8$-$1613 of $5.5^{+1.4}_{-1.1} , {rm kpc}$, under the assumption that the donor star is an unevolved, main sequence K3-5V star. This distance implies a natal kick velocity of $190 pm 30 , {rm km,s^{-1}}$ and therefore an asymmetrical supernova explosion within the Galactic disk as the expected birth mechanism. A lower distance is implied if the donor star has instead lost significant mass during the binary evolution. Hence, more accurate measurements of the binary inclination angle or donor star rotational broadening from future observations would help to better constrain the distance.