In the shadows of the V404 Cyg outburst in the summer of 2015, GS 1354-64 (BW Cir) went into outburst as well. We followed the evolution of the outburst at optical, UV and X-ray wavelengths using Faulkes Telescope South, SMARTS and Swift. The outburst was found to stay in the hard X-ray state, albeit being anomalously luminous with a peak X-ray luminosity exceeding 0.15 LEdd, which could be the most luminous hard state observed in a black hole X-ray binary. In this talk I will present our results showing that the the outburst evolution at all wavelengths can be explained by the disk instability model with irradiation and disk evaporation/condensation. In addition, I will present our long-term optical monitoring results that show a statistically significant, slow rise of the source brightness over the 7 years prior to the 2015 outburst. This could be the much-sought observational evidence of matter slowly accumulating in the accretion disk, and subsequently getting optically brighter, as predicted by the disk instability model.
|Original language||English (US)|
|Journal||American Astronomical Society, AAS Meeting #228|
|State||Published - Jun 1 2016|
Koljonen, K., Russell, D., Corral-Santana, J., Armas Padilla, M., Munoz-Darias, T., & Lewis, F. (2016). A "high-hard" outburst of the black hole X-ray binary GS 1354-64. American Astronomical Society, AAS Meeting #228, 228. http://adsabs.harvard.edu/abs/2016AAS...22840206K