Parallel tracks in infrared versus X-ray emission in black hole X-ray transient outbursts: a hysteresis effect?

Abstract

We report the discovery of a new hysteresis effect in black hole X-ray binary state transitions, that of the near-infrared (NIR) flux (which most likely originates in the jets) versus X-ray flux. We find, looking at existing data sets, that the infrared emission of black hole X-ray transients appears to be weaker in the low/hard state rise of an outburst than the low/hard state decline of an outburst at a given X-ray luminosity. We discuss how this effect may be caused by a shift in the radiative efficiency of the inflowing or outflowing matter, or variations in the disc viscosity or the spectrum/power of the jet. In addition we show that there is a correlation (in slope but not in normalisation) between infrared and X-ray luminosities on the rise and decline, for all three low-mass black hole X-ray binaries with well-sampled infrared and X-ray coverage: L_NIR propto L_x^(0.5-0.7). In the high/soft state this slope is much shallower; L_NIR propto Lx^(0.1-0.2), and we find that the NIR emission in this state is most likely dominated by the viscously heated (as opposed to X-ray heated) accretion disc in all three sources.

MNRAS accepted. 9 pages, 4 figures

References in corpus (7)

• A Long, Hard Look at the Low-Hard State in Accreting Black Holes
• Global optical/infrared - X-ray correlations in X-ray binaries: quantifying disc and jet contributions
• A radio-emitting outflow in the quiescent state of A0620-00: implications for modelling low-luminosity black hole binaries
• Jet-dominated advective systems: radio and X-ray luminosity dependence on the accretion rate
• Spitzer Reveals Infrared Optically-Thin Synchrotron Emission from the Compact Jet of the Neutron Star X-Ray Binary 4U 0614+091
• Further Evidence for Variable Synchrotron Emission in XTE J1118+480 in Outburst
• Keck Infrared Observations of GRO J0422+32 in Quiescence

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