Amalgame: cosmological constraints from the first combined photometric supernova sample

Brodie Popovic, Daniel Scolnic, Maria Vincenzi, Mark Sullivan, Dillon Brout, Bruno O. Sanchez, Rebecca Chen, Utsav Patel, Erik R. Peterson, Richard Kessler, Lisa Kelsey, Ava Claire Bailey, Phil Wiseman, Marcus Toy

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Future constraints of cosmological parameters from Type Ia supernovae (SNe Ia) will depend on the use of photometric samples, those samples without spectroscopic measurements of the SNe Ia. There is a growing number of analyses that show that photometric samples can be utilised for precision cosmological studies with minimal systematic uncertainties. To investigate this claim, we perform the first analysis that combines two separate photometric samples, SDSS and Pan-STARRS, without including a low-redshift anchor. We evaluate the consistency of the cosmological parameters from these two samples and find they are consistent with each other to under 1σ. From the combined sample, named Amalgame, we measure ΩM = 0.328 ± 0.024 with SN alone in a flat ΛCDM model, and ΩM = 0.330 ± 0.018 and w = when combining with a Planck data prior and a flat wCDM model. These results are consistent with constraints from the Pantheon+ analysis of only spectroscopically confirmed SNe Ia, and show that there are no significant impediments to analyses of purely photometric samples of SNe Ia. The data and results are made available at
Original languageEnglish
Pages (from-to)2100–2115
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Early online date8 Feb 2024
Publication statusPublished - 1 Apr 2024


  • astro-ph.CO
  • cosmology: cosmological parameters
  • cosmology: dark energy
  • stars: supernovae: general
  • transients: supernovae
  • cosmology: distance scale
  • cosmology: observations

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