Bridging the chirp-mass gap: searching for gravitational waves from inspiraling subsolar-mass ultra-compact binaries using LIGO O4ab data
Abstract
Gravitational-wave searches for subsolar-mass compact binaries have left a gap between the planetary-mass regime accessible to long-duration searches and the higher masses probed by conventional compact-binary analyses. We close this gap by searching for the inspiral of ultra-compact binaries with chirp masses 10−2--10−1 M⊙ in LIGO O4ab data. Using the statistically robust BinaryGFH-v2 method, a time-frequency technique to search for rapidly evolving inspirals lasting minutes to hours, we cover this previously challenging parameter space with a computational cost of only ∼ 350 CPU-hours, and find no significant candidates. We thus set 90\% confidence upper limits on the binary merger-rate density, providing the first gravitational-wave constraints across this chirp-mass range. Assuming that primordial-black-hole binaries formed in the early Universe with no binary suppression (fsup=1), these results provide the first gravitational-wave constraints on the primordial-black-hole \dmh fraction in this mass range, yielding upper limits with fPBH<1 for equal-mass binaries with component masses 10−2--10−1 M⊙ and asymmetric binaries with secondary masses m2=3×10−4--10−2 M⊙ for a primary mass m1=2.5 M⊙.
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BibTeX
@misc{miller2026bridging,
title = {{Bridging the chirp-mass gap: searching for gravitational waves from inspiraling subsolar-mass ultra-compact binaries using LIGO O4ab data}},
author = {Andrew L. Miller},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.16238},
eprint = {2609.16238},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.16238},
}
RIS
TY - UNPB
TI - Bridging the chirp-mass gap: searching for gravitational waves from inspiraling subsolar-mass ultra-compact binaries using LIGO O4ab data
AU - Andrew L. Miller
PY - 2026
DA - 2026/09/17
PB - arXiv
DO - 10.48550/arxiv.2609.16238
UR - https://arxiv.org/abs/2609.16238
AB - Gravitational-wave searches for subsolar-mass compact binaries have left a gap between the planetary-mass regime accessible to long-duration searches and the higher masses probed by conventional compact-binary analyses. We close this gap by searching for the inspiral of ultra-compact binaries with chirp masses 10^−2--10^−1 M_⊙ in LIGO O4ab data. Using the statistically robust BinaryGFH-v2 method, a time-frequency technique to search for rapidly evolving inspirals lasting minutes to hours, we cover this previously challenging parameter space with a computational cost of only ∼ 350 CPU-hours, and find no significant candidates. We thus set 90\% confidence upper limits on the binary merger-rate density, providing the first gravitational-wave constraints across this chirp-mass range. Assuming that primordial-black-hole binaries formed in the early Universe with no binary suppression (f_sup=1), these results provide the first gravitational-wave constraints on the primordial-black-hole \dmh fraction in this mass range, yielding upper limits with f_PBH<1 for equal-mass binaries with component masses 10^−2--10^−1 M_⊙ and asymmetric binaries with secondary masses m_2=3×10^−4--10^−2 M_⊙ for a primary mass m_1=2.5 M_⊙.
ER -