Can a steady-state Bekenstein-limited computation signal be separated from OC's millisecond pulsar gamma-ray emission at Fermi-LAT and CTA sensitivity?
Each millisecond pulsar (MSP) in OC emits a characteristic gamma-ray luminosity. The representative model uses spin-down power Ė = 4π²I_NS·Ṗ/P³ with P~3 ms, Ṗ~10⁻²⁰, giving Ė~3.5×10³³ erg/s and a 10% gamma-ray efficiency η_γ~0.1, yielding L_msp~3.5×10³² erg/s per MSP. The total flux at Earth is then F_msp = N_msp × L_msp / (4π × d²) where d = 5.49 kpc.
Converting to GeV/cm²/s: F_msp [GeV/cm²/s] = N_msp × L_msp [erg/s] / (4π × d_cm²) × (1 GeV / 1.602×10⁻³ erg)
Fermi-LAT 10-year sensitivity to a point source at 1 GeV is approximately 5×10⁻¹³ GeV cm⁻² s⁻¹. Sensitivity scales as 1/√T_obs, so at 15 years the reference sensitivity is ~4×10⁻¹³ GeV cm⁻² s⁻¹. The tool scales from this reference: F_sens(T) = 4×10⁻¹³ × √(15/T_obs) GeV/cm²/s.
CTA-South 50h sensitivity for a steady source above 100 GeV is approximately 5×10⁻¹⁴ GeV/cm²/s (Cherenkov Telescope Array Observatory 2019). This is the integrated sensitivity above ~100 GeV where MSP spectral cutoffs (~2–3 GeV) leave the field clear — making CTA particularly powerful for technosignature discrimination.
A civilization operating Bekenstein-limited computation via BZ extraction at power P_BZ would emit waste radiation. A fraction f_leak leaks as gamma-rays. The signal flux is: F_signal = f_leak × P_BZ / (4π × d²) converted to GeV/cm²/s. This represents a power-law continuum rather than the exponential MSP cutoff above ~3 GeV, which is the key spectral discriminant.
MSP gamma-ray spectra exhibit a characteristic exponential cutoff at ~2–3 GeV. Any BZ-driven emission mechanism would produce a harder spectrum. The SNR_separation metric quantifies whether the flux difference |F_signal − F_msp| exceeds the instrumental sensitivity, independent of the absolute brightness. A signal that sits below MSP emission in total flux but has a different spectral slope above 10 GeV could still be detectable — this is the CTA advantage.
The TRAPUM (TRAnsients and PUlsars with MeerKAT) survey is expected to find ~100 MSPs in OC within a few years, compared to ~25 currently known. Each confirmed MSP contributes to the modeled background and sharpens constraints on any residual unresolved emission. A 100-MSP population raises the foreground by ~4× and makes the technosignature detection problem correspondingly harder — unless the signal has a hard spectral component above 10 GeV.