Astrophysical Violations of the Kerr Bound as a Possible Signature of String Theory

Understand

In 4D general relativity, the angular momentum of a black hole is limited by the Kerr bound.

• We suggest that in string theory, this bound can be breached and compact black-hole-like objects can spin faster.
• Near such "superspinars," the efficiency of energy transfer from the accreting matter to radiation can reach 100%, compared to the maximum efficiency of 42% of the extremal Kerr (or 6% of the Schwarzschild) black hole.
• Finding such superspinning objects as active galactic nuclei, GBHCs, or sources of gamma ray bursts, could be viewed as experimental support for string theory.