A suite of high-resolution N-body simulations designed for the next generation of galaxy surveys.
Sahyadri is a suite of high-resolution N-body simulations targeting precision studies of the low-redshift Universe (z < 0.5). Named after the Sahyadri mountain range (Western Ghats) of India, the suite is designed to complement next-generation spectroscopic surveys including DESI Bright Galaxy Survey (BGS) and 4MOST.
The suite bridges a critical gap: existing parameter-varying simulation suites either prioritize large volumes at lower resolution (like Quijote and AbacusSummit) or focus on detailed galaxy physics in small volumes. Sahyadri achieves the mass resolution needed to resolve the faintest galaxies targeted by DESI BGS while varying cosmological parameters for derivative-based inference.
Sahyadri resolves approximately 40% more DESI BGS galaxies at z < 0.15 than existing parameter-varying suites, corresponding to roughly 1.6 million additional galaxies.
Six cosmological parameters varied around Planck 2018 baseline values with seed-matched initial conditions.
Seed-Matched Initial Conditions: All parameter-varied simulations share the same random seed, ensuring that differences in output are purely due to cosmological parameter changes. This enables clean numerical derivatives essential for Fisher matrix analyses and gradient-based emulator training.
Sinhagad is the pilot suite that preceded Sahyadri, using 256³ particles in the same box size. It served as a testing ground for the simulation pipeline, analysis codes, and compression strategies. Results from Sinhagad validated the approach before committing to the full-resolution Sahyadri runs.