A proposal for enhancing technosignature search toward the Galactic center

Abstract

We discuss the possibility of enhancing intelligent life searches toward the Galactic center. From the clockwork orbital motions of stars around the Sgr A${}^*$ black hole, we can determine the distance to the Galactic center at an exceptional accuracy, despite its remoteness $\sim 8.3$kpc. In addition, we can define precise reference epochs by selecting a prominent object such as the bright B-type star S2. These properties have a particular affinity for the coordinated signaling scheme which was hypothesized by Seto (2019) for systematically connecting intentional senders to searchers without a prior communication. If S2 is actually being used as a common reference clock, we can compress the search directions around the Galactic center by more than two orders of magnitude, with the scanning interval of $\sim16$yr.