Experimental Limits on Planetary Mass Primordial Black Hole Mergers

Area of Science:

• Physics
• Astronomy
• Cosmology

Background:

• Gravitational wave astronomy seeks to detect ripples in spacetime.
• Primordial black holes are hypothetical black holes formed in the early universe.
• High-frequency gravitational wave detection is an emerging field.

Purpose of the Study:

• To constrain the merger rate density of primordial black hole binaries.
• To establish new bounds using MHz-regime gravitational wave detection.
• To differentiate gravitational wave signals from background noise.

Main Methods:

• Utilizing cryogenic quartz bulk acoustic wave resonators as strain antennas.
• Collecting 61 days of non-continuous data.
• Employing coincident analysis between multiple detectors to exclude non-gravitational signals.

Main Results:

• Established bounds on the observable merger rate density for specific primordial black hole masses.
• Achieved a maximum limit on the merger rate density of R<1.3×10^18 kpc⁻³ yr⁻¹.
• Constrained yearly mergers to a reach of approximately the Solar System's distance (1.0×10⁻⁶ kpc).

Conclusions:

• The MAGE experiment provides significant constraints on primordial black hole merger rates.
• The findings exclude rare, strong events as non-gravitational background signals.
• This work advances the search for high-frequency gravitational waves and their sources.