A clean sightline to quiescence: multiwavelength observations of the high Galactic latitude black hole X-ray binary Swift J1357.2-0933
MetadataShow full item record
We present coordinated multiwavelength observations of the high Galactic latitude (b = +50°) black hole X-ray binary (BHXB) Swift J1357.2−0933 in quiescence. Our broad-band spectrum includes strictly simultaneous radio and X-ray observations, and near-infrared, optical, and ultraviolet data taken 1–2 d later. We detect Swift J1357.2−0933 at all wavebands except for the radio (f5 GHz < 3.9 μJy beam−1; 3σrms). Given current constraints on the distance (2.3–6.3 kpc), its 0.5–10 keV X-ray flux corresponds to an Eddington ratio LX/LEdd = 4 × 10−9–3 × 10−8 (assuming a black hole mass of 10 M⊙). The broad-band spectrum is dominated by synchrotron radiation from a relativistic population of outflowing thermal electrons, which we argue to be a common signature of short-period quiescent BHXBs. Furthermore, we identify the frequency where the synchrotron radiation transitions from optically thick-to-thin (νb ≈ 2–5 × 1014 Hz), which is the most robust determination of a ‘jet break’ for a quiescent BHXB to date. Our interpretation relies on the presence of steep curvature in the ultraviolet spectrum, a frequency window made observable by the low amount of interstellar absorption along the line of sight. High Galactic latitude systems like Swift J1357.2−0933 with clean ultraviolet sightlines are crucial for understanding black hole accretion at low luminosities.
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, ©: 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Showing items related by title, author, creator and subject.
Optical Precursors to Black Hole X-ray Binary Outbursts: An evolving synchrotron jet spectrum in Swift J1357.2-0933Russell, D.; Qasim, A.; Bernardini, F.; Plotkin, Richard; Lewis, F.; Koljonen, K.; Yang, Y. (2018)We present six years of optical monitoring of the black hole candidate X-ray binary Swift J1357.2-0933, during and since its discovery outburst in 2011. On these long timescales, the quiescent light curve is dominated by ...
Torres, M.; Jonker, P.; Miller-Jones, James; Steeghs, D.; Repetto, S.; Wu, J. (2015)We present time-resolved optical spectroscopy of the counterpart to the high-inclination black hole low-mass X-ray binary Swift J1357.2−0933 in quiescence. Absorption features from the mass donor star were not detected. ...
Kennea, J.; Romano, P.; Mangano, V.; Beardmore, A.; Evans, P.; Curran, Peter; Krimm, H.; Markwardt, C.; Yamaoka, K. (2011)We report on the detection and follow-up high-cadence monitoring observations of MAXI J1659-152, a bright Galactic X-ray binary transient with a likely black hole accretor, by Swift over a 27 day period after its initial ...