Disentangling the NIR/optical emission of the black hole XTE J1650−500 during outburst⋆
Laboratoire AIM, UMR 7158 CEA/DSM-CNRS-Université Paris Diderot,
Irfu/Service d’Astrophysique, CEA-Saclay, 91191
2 Institut Universitaire de France, 103 Bd Saint-Michel, 75005 Paris, France
3 François Arago Centre, APC, Université Paris Diderot, CNRS/IN2P3, CEA/DSM, Observatoire de Paris, 13 rue Watt, 75205 Paris Cedex 13, France
Received: 15 March 2012
Accepted: 27 September 2012
Context. While the sources of X-ray and radio emission in the different states of low-mass X-ray binaries are relatively well understood, the origin of the near-infrared (NIR) and optical emission is more often debated. It is likely that the NIR/optical flux originates from an amalgam of different emission regions, because it occurs at the intersecting wavelengths of multiple processes.
Aims. We aim to identify the NIR/optical emission region(s) of one such low-mass X-ray binary and black hole candidate, XTE J1650−500, via photometric, timing, and spectral analyses.
Methods. We present unique NIR/optical images and spectra, obtained with the ESO-New Technology Telescope, during the peak of the 2001 outburst of XTE J1650−500.
Results. The data suggest that the NIR/optical flux is due to a combination of emission mechanisms including a significant contribution from X-ray reprocessing and, at early times in the hard state, a relativistic jet that is NIR/radio dim compared to similar sources.
Conclusions. The jet of XTE J1650−500 is relatively weak compared to that of other black hole low-mass X-ray binaries, possibly because we observe as it is being “turned off” or quenched at the state transition. While there are several outliers to the radio-X-ray correlation of the hard state of low-mass X-ray binaries, XTE J1650−500 is the first example of an outlier to the NIR/optical-X-ray correlation.
Key words: accretion, accretion disks / ISM: jets and outflows / infrared: stars / X-rays: individuals: XTE J1650 / 500 / X-rays: binaries
© ESO, 2012