Are signatures of anti-de-Sitter black hole at the Galactic Center?
Using Schwarzschild – de-Sitter (Kottler) metric we derive a simple analytical relation between a shadow size and �-term. Current observations of the smallest spot to evaluate shadow size at the Galactic Center do not reach an accuracy comparable with cosmological �-term ∼ 10 −52 m −2 , however, if in reality we have dark energy instead of a constant �-term then dark energy may be a function depending on time and space and it could be approximated with a local constant �-term near the Galactic Center and it is important to introduce a procedure to evaluate the �term. We suggest such a procedure based on a black hole shadow evaluation. Surprisingly, current observational estimates of shadows are in agreement with anti-de-Sitter spacetimes corresponding to a negative �-term which is about −0.4 × 10 −20 m −2 . A negative �-term has been predicted in