Gravitational-wave astronomy — The effective-spin / mass-ratio correlation in binary black holes

LIGO-Virgo O2 data could detect, or at least meaningfully constrain, primordial black hole dark matter through mergers pairing a subsolar component with a primary above about 2 solar masses.

Four candidates passed a signal-to-noise threshold of 8 and a false alarm rate of 2 per year, but none was statistically significant; assuming a null, the 90% upper limits on the primordial black hole dark-matter fraction stayed above 1 for every mass function and both early and late binary formation prescriptions, so no part of the parameter space was excluded.

Why it matched: same research area

Eleven years of NANOGrav pulsar-timing data would reveal an isotropic stochastic gravitational-wave background.

The search found no evidence for a gravitational-wave background; the data instead set upper limits on the background's strain amplitude and constraints on supermassive black-hole binaries, cosmic strings and a primordial background.

Why it matched: same research area