New constraints on macroscopic compact objects as dark matter candidates from gravitational lensing of type Ia supernovae

We use the distribution, and particularly the skewness, of high redshift type Ia supernovae brightnesses relative to the low redshift sample to constrain the density of macroscopic compact objects (MCOs) in the Universe. The supernova data favor dark matter made of microscopic particles (such as the lightest supersymmetric partner) over MCOs with masses between 10-2M and 1010M at 89% confidence. Future data will greatly improve this limit. Combined with other constraints, MCOs larger than one-tenth the mass of Earth (∼10-7M) can be eliminated as the sole constituent of dark matter. © 2007 The American Physical Society.