Hawking emission from a light-formed black hole — formation threshold, evaporation timeline, and neutrino detectability at Omega Centauri's distance
A kugelblitz (German: "ball lightning") is a theoretical black hole formed not from collapsing matter but from a sufficiently intense concentration of electromagnetic radiation. When photon energy density in a region reaches ~c⁴/(G·r²), general relativity predicts that the energy itself curves spacetime enough to form a horizon. The concept was explored by Wheeler (1955) and elaborated in several theoretical contexts since. Unlike stellar black holes, a kugelblitz would be formed intentionally — a possible far-future engineering feat.
Dvali & Osmanov (2023, Int. J. Astrobiology 22:617, DOI: 10.1017/S1473550423000186, arXiv:2301.09575) examined the Hawking emission spectrum for small (high-temperature) black holes that emit all kinematically accessible Standard Model particles — the "democratic" emission regime. At Hawking temperatures above ~100 GeV, the hole emits all 106.75 effective SM degrees of freedom with roughly equal weight. In particular, the neutrino channel becomes substantial: at full SM temperatures, neutrinos carry roughly 45% of total Hawking power. This makes a hot kugelblitz a potential high-energy neutrino source detectable by IceCube or KM3NeT, even from Omega Centauri's distance of 5.49 kpc.
The Macro Transcension Hypothesis (MTH) proposes that advanced civilisations compress into compact, high-density structures — potentially including engineered black holes within dense stellar environments. Omega Centauri (NGC 5139, distance ~5.49 kpc, Harris 2010 rev.) is the target of choice for OCS: it is the most massive and metal-rich globular cluster in the Milky Way, hosts a candidate IMBH (Häberle et al. 2024), and provides the highest-density stellar environment within reach of current observatories. A kugelblitz maintained or produced inside OC would be at exactly 5.49 kpc, and the neutrino flux estimates here use that fixed distance.
The number of particle species accessible to Hawking emission depends on the hole's temperature relative to particle rest-mass thresholds. This tool uses a five-tier approximation:
T < 5.9×10⁹ K (0.51 MeV): photons only → g_eff = 2
T < 1.2×10¹⁰ K (1 MeV): add e⁺e⁻ → g_eff = 5.5
T < 1.7×10¹² K (146 MeV): add pions/muons → g_eff = 10.75
T < 1.16×10¹³ K (1 GeV): add light quarks/gluons → g_eff = 61.75
T ≥ 1.16×10¹³ K: full SM democratic emission → g_eff = 106.75
The total Hawking power is then scaled by g_eff/2 relative to the single-photon-species formula.
Forming a kugelblitz requires focusing electromagnetic radiation to extreme intensities. The Schwinger critical intensity I_S ≈ 2.3×10²⁹ W/m² is the threshold at which the QED vacuum becomes unstable to spontaneous e⁺e⁻ pair production from two photons (Breit-Wheeler process). If the required focusing intensity I_focus exceeds I_S, the beam would pair-produce before gravitational collapse occurs. Álvarez-Domínguez et al. (2024, PRL 133, 041401) analyse this constraint rigorously and show it sets a practical lower bound on achievable kugelblitz mass — the larger (cooler, lower-intensity) the target hole, the more feasible the formation. The ratio I_focus / I_S displayed here is the key figure of merit: below 1 is the "feasible in principle" regime.
r_s = 2GM/c²
T_H = ℏc³ / (8π G M k_B)
P_H = (g_eff/2) × ℏc⁶ / (15360π G² M²)
t_evap = (5120π G² M³ / ℏc⁴) × (2/g_eff)
I_focus = c⁹ / (32π G³ M²)
f_ν = 0.45 × clamp((log₁₀T_H − 10)/3, 0, 1)
F_ν = f_ν × P_H / (4π d²) where d = 5.49 kpc
IceCube (DeepCore + main array): the 10-year point-source sensitivity for a diffuse neutrino flux is approximately 10⁻¹² GeV/cm²/s at TeV energies (IceCube Collaboration 2020, Phys Rev Lett 124, 051103). KM3NeT/ARCA (Astroparticle Research with Cosmics in the Abyss): projected 10-year point source sensitivity ~3×10⁻¹³ GeV/cm²/s (Adrián-Martínez et al. 2016, J Phys G 43, 084001). These are approximate figures appropriate for an order-of-magnitude comparison; actual detection thresholds depend on spectral shape and background rejection.