Supernova microlensing as a probe of ultracompact minihalos and primordial cosmology
Abstract
We propose using supernova microlensing to search for ultracompact minihalos and other extended dark structures seeded by enhanced primordial small-scale power. Unlike conventional microlensing searches, which are often optimized for primordial black holes, cosmological supernovae are sensitive to lenses with physical sizes comparable to their Einstein radii (up to ∼ pc(M/104M⊙)1/2 scale), opening a qualitatively different region of dark object parameter space. We compute the extended object detection efficiency relative to point lenses. We then show how projected limits on the abundance of ultracompact minihalos can be mapped, in benchmark formation scenarios, onto constraints on the primordial power spectrum. With the Vera C. Rubin Observatory expected to deliver an unprecedented LSST supernova sample, supernova microlensing is poised to become a timely and complementary probe of small-scale structure and the physics of the early Universe.
Related
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BibTeX
@misc{croon2026supernova,
title = {{Supernova microlensing as a probe of ultracompact minihalos and primordial cosmology}},
author = {Djuna Croon and Sergio Sevillano Muñoz and Miguel Zumalacarregui},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.04308},
eprint = {2609.04308},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.04308},
}
RIS
TY - UNPB
TI - Supernova microlensing as a probe of ultracompact minihalos and primordial cosmology
AU - Djuna Croon
AU - Sergio Sevillano Muñoz
AU - Miguel Zumalacarregui
PY - 2026
DA - 2026/09/03
PB - arXiv
DO - 10.48550/arxiv.2609.04308
UR - https://arxiv.org/abs/2609.04308
AB - We propose using supernova microlensing to search for ultracompact minihalos and other extended dark structures seeded by enhanced primordial small-scale power. Unlike conventional microlensing searches, which are often optimized for primordial black holes, cosmological supernovae are sensitive to lenses with physical sizes comparable to their Einstein radii (up to ∼ pc(M/10^4M_⊙)^1/2 scale), opening a qualitatively different region of dark object parameter space. We compute the extended object detection efficiency relative to point lenses. We then show how projected limits on the abundance of ultracompact minihalos can be mapped, in benchmark formation scenarios, onto constraints on the primordial power spectrum. With the Vera C. Rubin Observatory expected to deliver an unprecedented LSST supernova sample, supernova microlensing is poised to become a timely and complementary probe of small-scale structure and the physics of the early Universe.
ER -