They are all faint galaxies, so any estimates on their baryonic mass are in the "challenge your assumptions" regime. And that "line" is pretty spurious, if I'm

They are all faint galaxies, so any estimates on their baryonic mass are in the "challenge your assumptions" regime. And that "line" is pretty spurious, if I'm reading the paper correctly they are saying the chance of the line happening randomly is 0.6% -- not very low, the sky is a huge place. the bullet galaxy that has the "rest of the dark matter" hasn't been found.