PNG-UNITsims: Halo clustering response to primordial non-Gaussianities as a function of mass

¹ Departamento de Física Teórica, Universidad Autónoma de Madrid, 28049 Madrid, Spain
e-mail: adrian.gutierrez@uam.es
² Centro de Investigación Avanzada en Física Fundamental (CIAFF), Facultad de Ciencias, Universidad Autónoma de Madrid, 28049 Madrid, Spain
³ Instituto de Física Teorica UAM-CSIC, c/ Nicolás Cabrera 13-15, Cantoblanco, 28049 Madrid, Spain
⁴ Institut de Física d’Altes Energies (IFAE) The Barcelona Institute of Science and Technology campus UAB, 08193 Bellaterra, Barcelona, Spain
⁵ Institute for Astronomy, University of Edinburgh, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
⁶ Donostia International Physics Centre, Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastian, Spain
⁷ Department of Physics and Astronomy, The University of Utah, 115 South 1400 East, Salt Lake City, UT 84112, USA
⁸ Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305, USA
⁹ Berkeley Center for Cosmological Physics, University of California, Berkeley, CA 94720, USA
¹⁰ International Centre for Radio Astronomy Research, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia

Received: 20 December 2023
Accepted: 10 May 2024

Abstract

This paper presents the PNG-UNITSIMS suite, which includes the largest full N-body simulation to date with local primordial non-Gaussianities (local PNG), the PNG-UNIT. The amplitude of the PNGs is given by f ^local_NL=100. The simulation follows the evolution of 4096³ particles in a periodic box with L_box = 1 h⁻¹ Gpc, resulting in a mass resolution of m_p = 1.24 × 10⁹ h⁻¹ M_⊙, enough to finely resolve the galaxies targeted by stage-IV spectroscopic surveys. The PNG-UNIT has fixed initial conditions with phases also matching the pre-existing UNIT simulation with Gaussian initial conditions. The fixed and matched initial conditions reduce the simulation uncertainty significantly. In this first study of the PNG-UNITSIMS, we measure the PNG response parameter, p, as a function of the halo mass. halos with masses between 1 × 10¹² and 5 × 10¹³ h⁻¹ M_⊙ are well described by the universality relation, given by p = 1. For halos with masses between 2 × 10¹⁰ and 1 × 10¹² h⁻¹ M_⊙ we find that p < 1, at a significance between 1.5 and 3.1σ. Combining all the halos between 2 × 10¹⁰ and 5 × 10¹³ h⁻¹ M_⊙, we find p consistent with a value of 0.955 ± 0.013, which is 3σ away from the universality relation. We demonstrate that these findings are robust to mass resolution, scale cuts and uncertainty estimation. We also compare our measurements to separate universe simulations, finding that the PNG-UNITSIMS constraints outperform the former for the setup considered. Using a prior on p as tight as the one reported here for DESI-like forecast can result in f_NL constraints comparable to fixing p. At the same time, fixing p to a wrong value (p = 1) may result in up to 2σ biases on f_NL.