Beyond $\Lambda$CDM with HI intensity mapping: robustness of cosmological constraints in the presence of astrophysics

Understand

Mapping the unresolved intensity of the 21-cm emission of neutral hydrogen (HI) is now regarded as one the most promising tools for cosmological investigation in the coming decades.

• Here, we investigate, for the first time, extensions of the standard cosmological model, such as modified gravity and primordial non-Gaussianity, taking self-consistently into account the present constraints on the astrophysics of HI clustering in the treatment of the brightness temperature fluctuations.
• To understand the boundaries within which results thus obtained can be considered reliable, we examine the robustness of cosmological parameter estimation performed via studies of 21-cm intensity mapping, against our knowledge of the astrophysical processes leading to HI clustering.
• Modelling of astrophysical effects affects cosmological observables through the relation linking the overall HI mass in a bound object, to the mass of the underlying dark matter halo that hosts it.