Description
Jets from stellar mass black holes in X-ray binaries (XRBs) and supermassive black holes in blazars provide distinct opportunities to study the jets of black holes across two different mass regimes. They also represent samples with very different selection effects. Historically, the apparent speeds of XRB jets have been observed to be lower than those of blazars, leading to the assumption that this reflects the underlying distributions of Lorentz factors, i.e. stellar mass black holes produce slower jets. In this talk, I will present our detailed modelling of the parent population for large-scale XRB jets, which accounts for the selection effects present in the observed sample. Using nested sampling, we determined that the Lorentz factors of the parent population of XRBs are best described by a power law with a slope of $b = 3.01_{-1.23}^{+0.89}$, the same form of model which has been historically applied to blazar jets. We can reject several other potential Lorentz factor distributions, such as Gaussian and Exponential distributions, using Bayes factors. When comparing our findings to the parent Lorentz distributions of Blazar jets documented in the literature, it is notable that we cannot rule out the possibility that both XRBs and Blazar jets share the same parent population Lorentz factor distribution. In other words, based on kinematics alone, jets from stellar mass black holes are consistent with being just as relativistic as those from supermassive black holes.
