Stage 3 experiments (Planck, BOSS) have shown that energy fluctuations at the end of inflation were not exactly scale-free (ns=0.97) and gravity waves were small (r), ruling out the simplest (𝛟2) inflation models. Spec-S5 will use the tool of the power spectrum of density fluctuations imprinted from the early universe, leveraging established technology that has matured from BOSS (Stage 3) to DESI (Stage 4) to Spec-S5 (Stage 5).
The Spec-S5 program is primarily motivated by the need to map an enormous volume of the Universe, which is only possible by extending to higher redshift. This dataset will enable high precision measurements of large-scale structure spanning distance, growth, and inflationary physics allowing a holistic study of fundamental physics such as:
BAO measurements at better than 0.1% precision over the redshift range 2.1 < z < 4.5.
RSD measurements on the growth of structure at 0.55% precision over the redshift range 2.1 < z < 4.5.
Measurements of \(N_\mathrm{eff}\) to a precision of 0.040 independent of CMB constraints.
Constraints on the summed mass of the neutrino mass eigenstates to a precision of 28 meV independent of low redshift measurements.
Constraints on the Local form of primordial non-Gaussianity to a precision \(\sigma(f^\mathrm{local}_\mathrm{nl}) = 1.4\).
Search for departures from scale invariance in the inflationary field at a precision that exceeds DESI forecasts by a factor of 4.
