Non-Gaussian bias parameter b_ϕ as a function of the halo mass for the different sets of simulations. The colour of the symbols and the dashed lines represent the mass resolution. Red: m_p = 1.5 × 10⁸ [h⁻¹ M_⊙]. Green: m_p = 1.2 × 10⁹ [h⁻¹ M_⊙]. Blue-Dark blue: m_p = 1.0 × 10¹⁰ [h⁻¹ M_⊙]. The dashed vertical lines represent the threshold of M_halo = 20m_part for each simulation. The pink solid line is the universality relation p = 1 for the b₁ values measured in the PNG-UNIT. The dashed pink line extrapolates the universality relation toward lower masses, using b₁ coming from Tinker et al. (2010). In solid circles, we use the best fit to Eq. (15) for estimating the power spectrum variance; in rings, we use the extrapolation method. Upper panel: measurements of b_ϕ in non-Gaussian simulations by fitting Eq. (11) (see Sect. 6.1). Lower panel: measurements of b_ϕ using the separate universe technique (see Sect. 6.2).