Search for Gravitational Waves from High-Mass-Ratio Compact-Binary Mergers of Stellar Mass and Subsolar Mass Black Holes.

We present the first search for gravitational waves from the coalescence of stellar mass and subsolar mass black holes with masses between 20-100  M_{⊙} and 0.01-1  M_{⊙}(10-10^{3}  M_{J}), respectively. The observation of a single subsolar mass black hole would establish the existence of primordial black holes and a possible component of dark matter. We search the ∼164 day of public LIGO data from 2015-2017 when LIGO-Hanford and LIGO-Livingston were simultaneously observing. We find no significant candidate gravitational-wave signals. Using this nondetection, we place a 90% upper limit on the rate of 30-0.01  M_{⊙} and 30-0.1  M_{⊙} mergers at <1.2×10^{6} and <1.6×10^{4}  Gpc^{-3}  yr^{-1}, respectively. If we consider binary formation through direct gravitational-wave braking, this kind of merger would be exceedingly rare if only the lighter black hole were primordial in origin (<10^{-4}  Gpc^{-3}  yr^{-1}). If both black holes are primordial in origin, we constrain the contribution of 1(0.1)M_{⊙} black holes to dark matter to <0.3(3)%.