BibTeX

@article{2508.15899v1,
Author        = {Konstantin Karchev and Roberto Trotta and Raul Jimenez},
Title         = {CIGaRS I: Combined simulation-based inference from SNae Ia and host
  photometry},
Eprint        = {2508.15899v1},
ArchivePrefix = {arXiv},
PrimaryClass  = {astro-ph.CO},
Abstract      = {Using type Ia supernovae (SNae Ia) as cosmological probes requires empirical
corrections, which correlate with their host environment. We present a unified
Bayesian hierarchical model designed to infer, from purely photometric
observations, the intrinsic dependence of SN Ia brightness on progenitor
properties (metallicity & age), the delay-time distribution (DTD) that governs
their rate as a function of age, and cosmology, as well as the redshifts of all
hosts. The model incorporates physics-based prescriptions for star formation
and chemical evolution from Prospector-beta, dust extinction of both galaxy and
SN light, and observational selection effects.
  We show with simulations that intrinsic dependences on metallicity and age
have distinct observational signatures, with metallicity mimicking the
well-known step of SN Ia magnitudes across a host stellar mass of $\approx
10^{10} M_{\odot}$. We then demonstrate neural simulation-based inference of
all model parameters from mock observations of ~16 000 SNae Ia and their hosts
up to redshift 0.9. Our joint physics-based approach delivers robust and
precise photometric redshifts (<0.01 median scatter) and improved cosmological
constraints, unlocking the full power of photometric data and paving the way
for an end-to-end simulation-based analysis pipeline in the LSST era.},
Year          = {2025},
Month         = {Aug},
Url           = {http://arxiv.org/abs/2508.15899v1},
File          = {2508.15899v1.pdf}
}