A Model of Spectral Line Broadening in Signal Forecasts for Line-intensity Mapping Experiments

Abstract Line-intensity mapping observations will find fluctuations of integrated line emission are attenuated by varying degrees at small scales due to the width profiles. This attenuation may significantly impact estimates astrophysical or cosmological quantities derived from measurements. We consider a theoretical treatment effect broadening on both clustering and shot-noise components power spectrum generic line-intensity using halo model. then possible simplifications allow easier application in analysis, particularly context inferences that require numerous, repeated, fast computations model signals across large parameter space. For CO Mapping Array Project CO(1–0) field z ? 3 serving as our primary case study, we expect ?10% spherically averaged average relevant k ? 0.2–0.3 Mpc ?1 compared ?25% for interferometric Millimetre-wave Intensity Experiment targeting shot noise lines 1–5 ? 1 . also nature amplitude errors introduced simplified treatments while an approximation single effective velocity scale is sufficient spectra, more careful necessary when considering other statistics such higher multipoles anisotropic voxel intensity distribution.