GW230529 in CCEGA: Radion Sidebands, Surface Redshift, and Einstein Telescope Falsification

The gravitational wave event GW230529 (m₂ ≈ 2.5 M☉) occupies the astrophysical mass gap between neutron stars and black holes, exhibiting no electromagnetic counterpart despite intensive searches. We analyze this event using the CCEGA (Constrained Coupling with Exponential Gravity Ansatz) framework, which predicts density-dependent gravitational coupling G_eff(ρ) = G_N exp(-ρ/ρ_c) with ρ_c = 7.4 ρ_nuc. We present three independent observational signatures: (1) Surface Redshift: For m₂ = 2.5 M☉, CCEGA predicts a surface radius R = 10.2 km (versus Schwarzschild R_s = 7.38 km), generating surface redshift z ≈ 0.65. This naturally suppresses electromagnetic emission while maintaining a physical surface (avoiding singularities). (2) Radion Sidebands: The modular field oscillates during merger with frequency f_rad = 250 Hz, generating a frequency comb spanning 240–2400 Hz with quality factor Q ≈ 200. (3) Tidal Deformability: CCEGA predicts intermediate tidal deformability Λ ≈ 50–150, resolvable with Einstein Telescope sensitivity. We calculate detectability in Einstein Telescope and identify three falsification tests distinguishing CCEGA from both standard GR black holes and neutron star scenarios by 2035.