Binary characteristics of a newly discovered black hole bainary MAXI J1910-057 studied by long-term multi-wavelength observations.
Abstract
MAXI J1910-057 was discovered by MAXI (Monitor of All-sky X-ray Image) as an X-ray nova on May 31, 2012. Subsequent observations suggest that this source is a low-mass black hole binary. We started observing the optical counterpart of this source with the MITSuME Akeno 50cm telescope from June 1, 2012. We present the broad-band spectral energy distribution (SED) for the two epochs during the X-ray outbursts, one at the highest X-ray luminosity and another at the transition from the soft to hard X-ray states transition.These SEDs indicate that the optical emission is brighter than that from the accretion disk expected from the the X-ray spectral model, and yet the optical photon index is similar to that from an accretion disk. We find that the optical characteristics during the X-ray outburst were consistent with those of reprocessed emission of the irradiating X-ray flux from the accretion disk and/or the companion. Interestingly we detected optical emission even after the X-rays faded. This optical emission during the X-ray quiescent state showed erratic variations and a different SED shape, suggesting a different origin such as synchrotron emission from the jet. We find the optical periodicity during the X-ray outburst, but did not find it during the X-ray quiescent state. It supports that the origin of the optical variation due to reprocessed emission from the companion irradiated by X-rays from accretion disk. Finally We constrain the type of the companion, and find it is likely a late K or M type star.
- Publication:
-
41st COSPAR Scientific Assembly
- Pub Date:
- July 2016
- Bibcode:
- 2016cosp...41E2124Y