Updated: November 24, 2017
If a jet's optical depth is > 1, particle acceleration is inefficient and it is unsuccessful at producing high energy particles. If a jet is successful at accelerating protons but the jet head cannot escape the stellar envelope then it is choked and only the neutrinos escape. If a jet is successful at accelerating protons and the jet head escapes the stellar envelope then it is visible both electromagnetically and in neutrinos.
See arXiv:1711.00470 for more information.