Optical Light Curves of Luminous Eclipsing Black Hole X-ray Binaries

TL;DR

This paper models optical light curves of luminous eclipsing black hole X-ray binaries, incorporating supercritical accretion and outflows, successfully reproducing observed features and providing insights into system parameters and ultraluminous X-ray sources.

Contribution

It introduces a more realistic outflow-inclusive model for optical light curves in black hole binaries, improving upon previous simpler models.

Findings

The outflow significantly affects eclipse depth in light curves.

The model accurately fits the V-band light curve of SS433.

Parameter ranges for accretion rate and donor star temperature are consistent with observations.

Abstract

We examine optical V-band light curves in luminous eclipsing black hole X-ray binaries, using a supercritical accretion/outflow model that is more realistic than the formerly used ones. In order to compute the theoretical light curve in the binary system, we do not only apply the global analytic solution of the disk, but also include the effect of the optically thick outflow. We found that the depth of eclipse of the companion star by the disk changes dramatically when including the effect of the outflow. Due to the effect of outflow, we can reproduce the optical light curve for typical binary parameters in SS433. Our model with outflow velocity v~3000 km/s can fit whole shape of the averaged V-band light curve in SS433, but we found a possible parameter range consistent with observations, such as \dot{M}~5000-10000 L_E/c^2 (with L_E being the Eddington luminosity and $c$ being the speed of light) and T_C~10000K-14000 K for the accretion rate and donor star temperature, respectively. Furthermore, we briefly discuss observational implications for ultraluminous X-ray sources.