Modest set of simulations of local-type primordial non-Gaussianity in the DESI era

A measurement of a primordial non-Gaussianity (PNG) signal through late- or early-Universe probes has the potential to transform our understanding of the physics of the primordial Universe. While large-scale structure observables in principle contain vital information, interpreting these measurements is challenging due to poorly understood astrophysical effects. Luckily, N-body simulations, such as the abacuspng set presented in this study, consisting of 9 boxes, each of size L₁₎ₗ=2 Gpc/h and particle mass of 1. 0110^10M_/h, provide a viable path forward. As validation, we find good agreement between the simulations and our expectations from one-loop perturbation theory (PT) and the ``separate universe'' method for the matter bispectrum, matter power spectrum and the halo bias parameter associated with PNG, b_. As a science application, we investigate the link between halo assembly bias and b_ for halo properties known to play a vital role in accurately predicting galaxy clustering: concentration, shear (environment), and accretion rate. We find a strong response for all three parameters, suggesting that the connection between b_ and the assembly history of halos needs to be taken into account by future PNG analyses. We further perform the first study of the b_ parameter from fits to early DESI data of the luminous red galaxy (LRG) and quasistellar object (QSO) samples and comment on the effect on f₍₋ constraints for the allowed galaxy-halo models (note that f₍₋{b_}{b_}). We find that the error on f₍₋ is 15, 8, 7 for the LRGs at z=0. 5 and z=0. 8 and QSOs at z=1. 4, respectively, suggesting that a thorough understanding of galaxy assembly bias is warranted so as to perform robust high-precision analysis of local-type PNG with future surveys.