Dependence of Cosmological Constraints on Gray Photometric Zero-point Uncertainties of Supernova Surveys

Journal Article · 05 March 2023 · The Astrophysical Journal

DOI: https://doi.org/10.3847/1538-4357/acad80 · OSTI ID:1960091

Brownsberger, Sasha R. ; Brout, Dillon ; Scolnic, Daniel ; Stubbs, Christopher W. ; Riess, Adam G.

Abstract Type Ia supernova (SN) measurements of the Hubble constant, H ₀ ; cosmic mass density, Ω _M ; and dark energy equation-of-state parameter, w , rely on heterogeneous SN surveys across three decades of observation. These distinct surveys may have undiagnosed, relative photometric zero-point errors. We determine the sensitivities of the SH0ES+Pantheon+ cosmological constraints to unknown gray systematics in the photometric zero-point calibration between the 19 surveys that comprise the Pantheon+ SN compendium. Varying the surveys’ gray zero-points simultaneously with cosmological parameters, we determine that the SH0ES+Pantheon+ measurement of H ₀ is robust against gray intersurvey photometric miscalibration. Specifically, uncalibrated intersurvey systematics could represent a source of uncertainty no larger than 0.39 km s ⁻¹ Mpc ⁻¹ for H ₀ . This modest increase in H ₀ uncertainty could not account for the 7 km s ⁻¹ Mpc ⁻¹ “Hubble tension” between the SH0ES measurement of H ₀ and the Planck ΛCDM-based inference of H ₀ . However, the SH0ES+Pantheon+ best-fit values of Ω _M and w are not robust against gray zero-point error, slipping by up to 0.16 and −0.63. Because measurements of Ω _M and w depend on intrasurvey cross-band calibration, the hypothetical gray miscalibration underestimates the sensitivity of these measurements to zero-point miscalibration. Because the Pantheon+ compendium contains many surveys that share low- z Hubble flow (HF) and Cepheid-paired SNe, intersurvey photometric calibration errors do not significantly impede the joint use of SH0ES and Pantheon+ to measure H ₀ to 1% accuracy. However, H ₀ constraints that rely on one HF survey but numerous galactic distance calibration surveys are susceptible to intersurvey photometric miscalibration.

• Research Organization: Harvard Univ., Cambridge, MA (United States)
• Sponsoring Organization: National Aeronautics and Space Administration (NASA); Space Telescope Science Institute (STScI); USDOE; USDOE Office of Science (SC)
• Grant/Contract Number: SC0007881; SC0010007
• OSTI ID: 1960091
• Journal Information: The Astrophysical Journal, Journal Name: The Astrophysical Journal Journal Issue: 2 Vol. 944; ISSN 0004-637X
• Publisher: American Astronomical SocietyCopyright Statement
• Country of Publication: United States
• Language: English