What is the mass and momentum of a relativistic jet? Relativistic jets from accreting black holes are powerful radiation sources, but carries some ionized matter along. What are the estimates or observations of the mass or momentum flow in such jets?
I am not expert in that field, but I found a number and a reference:

A paper by E. Memola et al. on Theoretical thermal X-ray spectra of relativistic MHD jets assumes a mass flow of $\dot{M}_{\rm jet}=10^{-8}M_\odot {\rm yr}^{−1}$ for a central object of $5 M_\odot$
The paper The theory and simulation of relativistic jet formation: towards a unified model for micro- and macroquasars by David L. Maier (see also arXiv/astro-ph/0312048) looks like it may contain more insights, but I did not go through it in detail.