We present updated forecasts for the scientific performance of the degree-scale (0.5 deg FWHM at 93 GHz), deep-field survey to be conducted by the Simons Observatory (SO). By 2027, the SO Small Aperture Telescope (SAT) complement will be doubled from three to six telescopes, including a doubling of the detector count in the 93 GHz and 145 GHz channels to 48,160 detectors. Combined with a planned extension of the survey duration to 2035, this expansion will significantly enhance SO's search for a B-mode signal in the polarisation of the cosmic microwave background, a potential signature of gravitational waves produced in the very early Universe. Assuming a 1/f noise model with knee multipole ℓknee = 50 and a moderately complex model for Galactic foregrounds, we forecast a 1σ (or 68% confidence level) constraint on the tensor-to-scalar ratio r of σr = 1.2 × 10-3, assuming no primordial B-modes are present. This forecast assumes that 70% of the B-mode lensing signal can ultimately be removed using high resolution observations from the SO Large Aperture Telescope (LAT) and overlapping large-scale structure surveys. For more optimistic assumptions regarding foregrounds and noise, and assuming the same level of delensing, this forecast constraint improves to σr = 7 × 10-4. These forecasts represent a major improvement in SO's constraining power, being a factor of around 2.5 times better than what could be achieved with the originally planned campaign, which assumed the existing three SATs would conduct a five-year survey.

Abril-Cabezas, I., Adachi, S., Ade, P., Adler, A., Agrawal, P., Aguirre, J., et al. (2026). The Simons Observatory: forecasted constraints on primordial gravitational waves with the expanded array of Small Aperture Telescopes. JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 2026(04) [10.1088/1475-7516/2026/04/051].

The Simons Observatory: forecasted constraints on primordial gravitational waves with the expanded array of Small Aperture Telescopes

Astori, F.;Bizzarri, L.;Coppi, G.;Fanfani, V.;Nati, F.;Novelli, A.;Poletti, D.;Scalcinati, L.;Souverin, T.;Zannoni, M.;
2026

Abstract

We present updated forecasts for the scientific performance of the degree-scale (0.5 deg FWHM at 93 GHz), deep-field survey to be conducted by the Simons Observatory (SO). By 2027, the SO Small Aperture Telescope (SAT) complement will be doubled from three to six telescopes, including a doubling of the detector count in the 93 GHz and 145 GHz channels to 48,160 detectors. Combined with a planned extension of the survey duration to 2035, this expansion will significantly enhance SO's search for a B-mode signal in the polarisation of the cosmic microwave background, a potential signature of gravitational waves produced in the very early Universe. Assuming a 1/f noise model with knee multipole ℓknee = 50 and a moderately complex model for Galactic foregrounds, we forecast a 1σ (or 68% confidence level) constraint on the tensor-to-scalar ratio r of σr = 1.2 × 10-3, assuming no primordial B-modes are present. This forecast assumes that 70% of the B-mode lensing signal can ultimately be removed using high resolution observations from the SO Large Aperture Telescope (LAT) and overlapping large-scale structure surveys. For more optimistic assumptions regarding foregrounds and noise, and assuming the same level of delensing, this forecast constraint improves to σr = 7 × 10-4. These forecasts represent a major improvement in SO's constraining power, being a factor of around 2.5 times better than what could be achieved with the originally planned campaign, which assumed the existing three SATs would conduct a five-year survey.
Articolo in rivista - Articolo scientifico
CMBR experiments; cosmological parameters from CMBR; gravitational waves and CMBR polarization;
English
16-apr-2026
2026
2026
04
051
open
Abril-Cabezas, I., Adachi, S., Ade, P., Adler, A., Agrawal, P., Aguirre, J., et al. (2026). The Simons Observatory: forecasted constraints on primordial gravitational waves with the expanded array of Small Aperture Telescopes. JOURNAL OF COSMOLOGY AND ASTROPARTICLE PHYSICS, 2026(04) [10.1088/1475-7516/2026/04/051].
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/10281/604562
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