Testing the No-Hair Theorem with Observations of Black Holes in the Electromagnetic Spectrum

Understand

According to the no-hair theorem, astrophysical black holes are uniquely described by their mass and spin.

• In this paper, we review a new framework for testing the no-hair hypothesis with observations in the electromagnetic spectrum.
• The approach is formulated in terms of a Kerr-like spacetime containing a quadrupole moment that is independent of both mass and spin.
• If the no-hair theorem is correct, then any deviation from the Kerr metric quadrupole has to be zero.