2026/01/12 by Saee Dhawalikar, Shadab Alam, Aseem Paranjape +1
#astro-ph.CO
paper · pdf · doi:10.1088/1475-7516/2026/07/028
We present Sahyadri, a suite of cosmological N-body simulations designed to enable precision studies of the low-redshift Universe with next-generation spectroscopic surveys. Sahyadri includes systematic variations of four cosmological parameters around Planck 2018 constraints, with seed-matched initial conditions enabling cosmological parameter derivatives. It is planned to ultimately extend to six parameters. Each simulation evolves 20483 particles in a periodic box of side length 200 h-1 Mpc, yielding a particle mass of m_\rmp = 8.1 × 107 h-1 M\odot in the fiducial Planck 2018 cosmology. This resolution enables robust identification of dark matter halos down to M\rm min = 3.2 × 109 h-1 M_\odot, which represents a factor of ∼25 improvement over the AbacusSummit suite, and is over two orders of magnitude better than the Quijote and Aemulus suites. We estimate that approximately 40% of DESI BGS galaxies at redshift z < 0.15 - roughly 1.6 million objects - reside in halos accessible to Sahyadri but beyond the reach of existing parameter-varying simulation suites. We demonstrate Sahyadri's capabilities through measurements of the matter power spectrum, halo mass function and power spectrum, and beyond 2-point statistics such as the Voronoi volume function and k\rm th nearest neighbour statistics, showing excellent agreement with theoretical predictions and significant sensitivity to Ω\rm m variations. We implement a custom compression scheme reducing storage requirements by a factor of ∼3 while maintaining sub-percent clustering accuracy. Key data products are publicly available.