Heated CMB Term
The CMB blackbody spectrum is extraordinarily pure, but precision spectral measurements reveal residuals that are consistent with a small monopole spectral distortion — an effective 'heated CMB' term — whose amplitude and spectral shape constrain energy injection into the photon-baryon plasma at redshifts 104 < z < 106. ΛCDM predicts spectral distortions from Silk damping and from the decay of hypothetical primordial magnetic fields or unstable particles, but the measured amplitude is sensitive to the assumed energy injection history. In SCT, the collision event deposited kinetic energy into the plasma in a burst, but the thermalization of pre-existing matter — compact objects, dense stellar remnants, and metal-enriched gas — provided additional energy injection sources that are not present in the standard ΛCDM scenario. These pre-existing high-entropy objects did not instantly achieve perfect Bose-Einstein equilibrium with the surrounding photon gas; their thermalization proceeded over a range of redshifts, injecting energy into the photon bath at epochs that modify the μ- and y-distortion amplitudes.
The magnitude of the SCT-predicted spectral distortion depends on the mass fraction of pre-existing compact objects and the timescales over which they lost energy to the radiation field. This is a genuine prediction of SCT's pre-existing matter premise that is in principle measurable by future spectral distortion missions. Crucially, the distortion pattern is distinct from that produced by dissipation of primordial magnetic fields or by decaying particles, because it has a specific injection redshift distribution set by the thermalization physics of stellar remnants in a collision-heated plasma rather than by the slow decay of primordial relics. Future instruments capable of measuring CMB spectral distortions at the 10−7 level will provide a discriminating test of this SCT prediction.