Kilonovae (KNe) are the electromagnetic signatures of neutron star mergers and are likely the dominant site of cosmic r-process nucleosynthesis. However, their intrinsic rate remains poorly constrained due to a paucity of confirmed events. We use the All-Sky Automated Survey for Supernovae (ASAS-SN) to place limits on the rate of bright, nearby KNe over an 11-year baseline ranging from 2014 to 2024. To evaluate the survey's completeness for KNe, we employ an injection-recovery simulation using a shock-cooling cocoon model calibrated to the early blue emission of the only well-sampled KN, SSS17a (AT 2017gfo). Finding no KNe within the survey, we calculate a 2σ (∼95%) upper limit on the local volumetric KN rate of RKN<4400yr−1Gpc−3. Despite ASAS-SN's shallower limiting magnitude compared to other time-domain searches, its continuous, high-cadence, all-sky monitoring yields a constraint that is competitive with the strongest results from electromagnetic surveys but remains a factor of 18 higher than the LIGO-Virgo-KAGRA GWTC-4 estimate of the binary neutron star merger rate.
@article{arxiv.2603.26871,
title = {ASAS-SN Rates IV: Constraints on the Kilonova Rate},
author = {Dhvanil D. Desai and Benjamin J. Shappee and Christopher S. Kochanek and Krzysztof Z. Stanek and Katie Auchettl and John F. Beacom and Jeff Cooke and Subo Dong and Willem B. Hoogendam and Jose L. Prieto and Todd A. Thompson and Michael A. Tucker and Natasha Van Bemmel},
journal= {arXiv preprint arXiv:2603.26871},
year = {2026}
}