Constraints on compact objects from the Dark Energy Survey five-year supernova sample

TL;DR

This study uses supernova lensing data from the Dark Energy Survey to place limits on the fraction of matter in compact objects over cosmological distances, providing new constraints independent of background cosmology.

Contribution

It presents the first constraints on the fraction of matter in compact objects using supernova lensing magnification data from DES, accounting for various cosmological priors and systematics.

Findings

Fraction of matter in compact objects < 0.12 at 95% CL

Results are robust against different cosmological priors

Constraints are likely conservative, with potential systematic effects discussed

Abstract

Gravitational lensing magnification of Type Ia supernovae (SNe Ia) allows information to be obtained about the distribution of matter on small scales. In this paper, we derive limits on the fraction $\alpha$ of the total matter density in compact objects (which comprise stars, stellar remnants, small stellar groupings and primordial black holes) of mass $M > 0.03 M_{\odot}$ over cosmological distances. Using 1,532 SNe Ia from the Dark Energy Survey Year 5 sample (DES-SN5YR) combined with a Bayesian prior for the absolute magnitude $M$, we obtain $\alpha < 0.12$ at the 95\% confidence level after marginalisation over cosmological parameters, lensing due to large-scale structure, and intrinsic non-Gaussianity. Similar results are obtained using priors from the cosmic microwave background, baryon acoustic oscillations and galaxy weak lensing, indicating our results do not depend on the background cosmology. We argue our constraints are likely to be conservative (in the sense of the values we quote being higher than the truth), but discuss scenarios in which they could be weakened by systematics of the order of $\Delta \alpha \sim 0.04$