AbacusPNG: A modest set of simulations of local-type primordial non-Gaussianity in the DESI era

Abstract

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. $N$-body simulations, such as the public \textsc{AbacusPNG} set presented in this study, consisting of 9 boxes, each of size $L_{\mathrm{box}}=2\mathrm{Gpc}/h$ and particle mass of $1.01\times 10^{10}{M}_{\odot }/h$, provide a viable path forward. As validation, we find good agreement between the simulations and our expectations from one-loop perturbation theory and the `separate universe' method for the matter bispectrum, matter power spectrum and the halo bias parameter associated with PNG, $b_{\varphi }$. As a science application, we investigate the link between halo assembly bias and $b_{\varphi }$ 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 $b_{\varphi }$ and the assembly history of halos needs to be taken into account by future PNG analyses. We further perform the first study of the $b_{\varphi }$ parameter from fits to early DESI data of the luminous red galaxy (LRG) and quasi-stellar object (QSO) samples and comment on the effect on $f_{\mathrm{NL}}$ constraints for the allowed galaxy-halo models (note that $\sigma [f_{\mathrm{NL}}]\propto \frac{\sigma [b_{\varphi }]}{b_{\varphi }}$). We find that the error on $f_{\mathrm{NL}}$ is 21, 6, 22 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. Simulations publicly available at https://app.globus.org/file-manager?origin_id=ffc65d7a-0bf9-11ec-90b4-41052087bc27

21 pages, 7 figures, 2 tables