Context:
• New theoretical study (accepted in Nuclear Physics B, Aug 2024) proposes that hypothetical ultra-small black holes – termed “black hole morsels” – created during violent black hole merger events may produce detectable gamma-ray signatures.
• These could act as natural probes of quantum gravity.
Key Highlights:
Quantum Gravity Background
• Gravity merges with quantum mechanics at Planck-scale regime — unresolved in modern physics.
• Hawking (1970s) showed black holes emit faint Hawking Radiation due to quantum effects near event horizon.
• Large astrophysical black holes → radiation too cold to detect.
Black Hole Morsels Hypothesis
• “Morsels” = hypothetical micro-black holes, ~mass of asteroid.
• Could “pinch-off” as tiny dense pockets of spacetime during black hole merger.
• Signatures expected:
– high-energy gamma ray photons
– neutrinos
– delayed bursts after merger events
• Evaporation time: milliseconds → years (mass dependent).
Observational Implications
• Gamma-ray emission would be more isotropic (not highly beamed → unlike usual GRBs).
• Present-day telescopes already capable of searching for bursts:
– HESS (Namibia)
– HAWC (Mexico)
– LHAASO (China)
– Fermi Gamma-ray Space Telescope
• Researchers used HESS follow-up data on past mergers to set upper limits on possible morsel mass.
Relevant Prelims Points:
• Hawking Radiation → quantum effect; particle pair production near horizon.
• Quantum Gravity → attempts to unify Einstein’s GR (continuum spacetime) with QM.
• Multi-messenger astronomy → gravitational waves + EM radiation + neutrinos combined.
• GRBs = strongest EM events in universe; usually beamed jets from collapsing massive stars or mergers.
Relevant Mains Points:
• Why important? → accessible empirical window into quantum gravity without needing Planck-energy accelerators (beyond LHC scale).
• Potential to falsify or refine models → string theory, loop quantum gravity, extra-dimensional models.
• Uncertainty: morsels not yet detected; merger micro–fragmentation not fully modelled.
Way Forward:
• More high-cadence post-merger monitoring by gamma observatories.
• Combine with GW detectors (LIGO, Virgo, KAGRA) for timing triangulation.