Observational Constraints on Non-monotonic Infrared Emissions: Integrating Gaia–WISE Data with Thermodynamic Signature Boundary Conditions (TSBC)

Traditional infrared (IR) technosignature searches have long operated under the assumption that advanced civilizations produce a smooth, monotonic waste-heat excess. This paper challenges that paradigm by introducing the Thermodynamic Signature Boundary Condition (TSBC), a framework suggesting that as civilizations approach extreme thermodynamic efficiency (\eta \rightarrow 1), their thermal signatures may become spectrally selective and non-monotonic. ​To operationalize this theory, we present an observational pipeline that integrates Gaia astrometry and WISE mid-infrared photometry. By converting angular measurements into physical scales and employing magnitude-to-flux transformations, we define criteria for identifying anomalous IR structures. Our methodology specifically focuses on three diagnostic pillars: (1) Non-monotonic Spectral Energy Distributions (SEDs), particularly localized W4-band enhancement; (2) Statistical Isolation, utilizing Poisson-based tests to distinguish candidates from astrophysical backgrounds; and (3) Spatial Context, leveraging Gaia-derived distances to constrain physical luminosity. ​We argue that highly optimized civilizations may exhibit "thermodynamic camouflage," where increasing total energy throughput leads to reduced broadband visibility. Our analysis demonstrates that identifying these subtle, spectrally selective anomalies is essential for the next generation of SETI research. The TSBC framework provides a robust quantitative basis for prioritizing candidates that cannot be explained by conventional monotonic dust models, shifting the search from conspicuous infrared beacons to structured thermal irregularities.