Eccentricity of HLX-1
MetadataShow full item record
We compare the outer radius of the accretion disc in the intermediate-mass black hole candidate HLX-1 as estimated from the ultraviolet/optical continuum, with the values estimated from its outburst decline time-scales. We fit the Swift 2010 outburst decline light curve with an exponential decay, a knee and a linear decay. We find that the disc has an outer radius of 1012 ≤ Rout ≤ 1013 cm, only an order of magnitude larger than typical accretion discs in the high/soft state of Galactic black holes. By contrast, the semimajor axis is ≈ a few ×1014 cm. This discrepancy can be explained with a highly eccentric orbit. We estimate the tidal truncation radius and circularization radius around the black hole at periastron, and impose that they are similar or smaller than the outer disc radius. We obtain that e ≥ 0.95, that the radius of the donor star is ≤ a few solar radii and that the donor star is not at risk of tidal disruption. If the companion star fills its Roche lobe and impulsively transfers mass only around periastron, secular evolution of the orbit is expected to increase eccentricity and semimajor axis even further. We speculate that such extremely eccentric systems may have the same origin as the S stars in the Galactic Centre.
Copyright © 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.
Showing items related by title, author, creator and subject.
Russell, Thomas; Soria, Roberto; Motch, C.; Pakull, M.; Torres, M.; Curran, Peter; Jonker, P.; Miller-Jones, James (2014)We present Very Large Telescope optical spectra of the black hole candidate X-ray binary MAXI J1836−194 at the onset of its 2011 outburst. Although the spectrum was taken at the beginning of the outburst and contains a ...
Strader, J.; Chomiuk, L.; Maccarone, T.; Miller-Jones, James; Seth, A. (2012)Hundreds of stellar-mass black holes probably form in a typical globular star cluster, with all but one predicted to be ejected through dynamical interactions. Some observational support for this idea is provided by the ...
Russell, Thomas; Soria, Roberto; Miller-Jones, James; Curran, Peter; Markoff, S.; Russell, D.; Sivakoff, G. (2014)We present the results of our quasi-simultaneous radio, submm, infrared, optical and X-ray study of the Galactic black hole candidate X-ray binary MAXI J1836-194 during its 2011 outburst. We consider the full multiwavelength ...