Precision tests of CO and [CII] power spectra models against simulated intensity maps

Abstract Line intensity mapping (LIM) is an emerging technique with a unique potential to probe wide range of scales and redshifts. Realizing the full LIM, however, relies on accurate modeling signal. We introduce extended halo model for power spectrum fluctuations CO rotational lines [CII] fine transition line in real space, nonlinearities matter biasing relation between underlying dark distribution. also compute stochastic contributions beyond Poisson approximation using framework. To establish accuracy model, we create first cosmological-scale simulations maps, MithraLIMSims, at redshifts 0.5 ≤ z≤6, catalogs from Hidden-Valley simulations, painting halos according mass-redshift-luminosity relations each line. show that z=1 k max ≲ 0.8 Mpc -1 1h, predictions clustering (with only two free parameters) are agreement measured better than 5%. At higher redshift z=4.5, this remarkable extends smaller scale 2 1h. Furthermore, large scales, CII spectra non-Poissonian, amplitudes reproduced reasonably well by prescription. Lastly, assess performance theoretical baryon acoustic oscillations (BAO) hypothetical LIM surveys probing z=1, can be deployed within decade, will able make high significance measurement BAO. On longer time scale, space-based mission uniquely measure BAO unprecedented precision.