Horizonless ultracompact objects and dark matter in quadratic gravity
arXiv:1912.13333 · doi:10.1088/1475-7516/2020/02/018
Abstract
We show that in quadratic gravity sufficiently light objects must be horizonless and construct explicit analytic examples of horizonless ultracompact objects (UCOs), which are more compact than Schwarzschild black holes. Due to the quadratic terms, gravity becomes soft and eventually vanishes in the high-energy limit leading to a "linearization mechanism": light objects can be described by the linearized theory when their Schwarzschild radius is smaller than the Compton wavelength of the new gravitational degrees of freedom. As a result, we can analytically describe UCOs with a mass-to-radius ratio higher than for a Schwarzschild black hole. The corresponding spacetime is regular everywhere. We show that the Ostrogradsky instabilities can be avoided and discuss the relation with the Higgs vacuum metastability. Due to the lack of a horizon, light UCOs do not evaporate. Therefore, they may play the role of dark matter. We briefly discuss their phenomenology.
v2: 28 pages, 2 figures. v2 has an updated list of references and minor modifications, it matches the published version
References in corpus (18)
- Multi-messenger Observations of a Binary Neutron Star Merger
- Limits on the Macho Content of the Galactic Halo from the EROS-2 Survey of the Magellanic Clouds
- Echoes of ECOs: gravitational-wave signatures of exotic compact objects and of quantum corrections at the horizon scale
- Cosmic microwave background limits on accreting primordial black holes
- The merger rate of primordial-black-hole binaries
- Primordial black hole dark matter from single field inflation
- No-ghost theorem for the fourth-order derivative Pais-Uhlenbeck oscillator model
- Primordial Black Holes and Slow-Roll Violation
- CMB bounds on disk-accreting massive Primordial Black Holes
- Black Holes in Higher-Derivative Gravity
- Exactly solvable PT-symmetric Hamiltonian having no Hermitian counterpart
- Metastability in Quadratic Gravity
- Do massive compact objects without event horizon exist in infinite derivative gravity?
- Softened Gravity and the Extension of the Standard Model up to Infinite Energy
- On the Quantisation of Complex Higher Derivative Theories and Avoiding the Ostrogradsky Ghost
- Nonlocal star as a blackhole mimicker
- Pais-Uhlenbeck Oscillator and Negative Energies
- Fakeons and the classicization of quantum gravity: the FLRW metric