Fermi Paradox (Part 2) - Alien 'call signs'

2. Transit Light-curve Signatures of Artificial Objects Luc F. A. Arnold

This is a great answer to the Fermi Paradox.  Alien 'call signs', advanced alien civilization/s who have maybe left the inner rim and colonized the outer rim of our galaxy, have set up call signs, geometric patterns, more so massive triangular or other polygon shapes that orbit stars, suns, planets emitting signals of sorts, or expecting us to tune in on a signal (which we may not be advanced enough to detect, but at least we can see these huge shapes i.e light  signatures), but are generally quite, hence this Fermi Paradox answer; in the sense we need to find these Alien 'call signs', rather than them seeking us out.