Bursty star formation forces a major revision of cosmic survey noise

Standard forecasts for line-intensity mapping assume modest scatter in how efficiently halos convert gas into stars, but JWST reveals that star formation at z~4–6 is far more erratic. Propagating this burstiness through the shot-noise power spectrum yields a clean multiplicative boost factor for each emission line: Hα brightens by ~7×, while longer-lived tracers like [CII] and CO gain factors of 2.5–3.5. The upside is better signal detectability and reduced contamination from foreground interlopers; the downside is degraded baryon acoustic oscillation measurements. The same shot-noise excess also becomes a probe of star-formation physics itself, with tomography and cross-line correlations constraining the amplitude, halo-mass dependence, and timescale of the bursts.