Line Intensity Mapping with [C II] and CO(1-0) as Probes of Primordial Non-Gaussianity

Constraints on primordial non-Gaussianity (PNG) will shed light on the origin of primordial fluctuations and the physics of the early universe. The intensity mapping technique is a promising probe of structure formation on large scales; at high redshifts, it can provide complementary information to other cosmological probes. We explore the potential of future wide-field [C II] and CO intensity mapping surveys in constraining PNG of the local shape, which induces a distinct, scale-dependent correction to the line bias. We explore the parameter space of CO and [C II] survey designs that can achieve the nominal target of sigma(f(NL)(loc)) = 1, and further calculate what constraints such surveys can place on PNG of the equilateral, orthogonal, and quasi-single field shapes. We further test the dependence of these constraints on various model assumptions; namely the halo mass function, modeling of line bias, and correlation between mass and [C II]/CO luminosity. We find that the ability of CO and [C II] intensity mapping surveys to constrain f(NL)(loc) relies heavily on the spectral (redshift) coverage, requiring at least a coverage of an octave in frequency, to produce significant results, with the optimized surveys generally covering between z similar to [2-8]. As this redshift window partially overlaps with 21 cm EoR experiments like the Hydrogen Epoch of Reionization Array (HERA), we additionally explore the prospects for a hypothetical set of surveys to place constraints on sigma(f(NL)(loc)) utilizing multi-tracer analysis between the lines of H I, CO, and [C II].