High-cadence observations of the Galactic bulge by the microlensing surveys led to the discovery of a handful of extremely short-timescale microlensing events that can be attributed to free-floating or wide-orbit planets .
Here , we report the discovery of another strong free-floating planet candidate , which was found from the analysis of the gravitational microlensing event OGLE-2019-BLG-0551 .
The light curve of the event is characterized by a very short duration ( \lesssim 3 d ) and a very small amplitude ( \lesssim 0.1 mag ) .
From modeling of the light curve , we find that the Einstein timescale , t _ { E } = 0.381 \pm 0.017 d , is much shorter , and the angular Einstein radius , \theta _ { E } = 4.35 \pm 0.34 \mu as , is much smaller than those of typical lensing events produced by stellar-mass lenses ( t _ { E } \sim 20 d , \theta _ { E } \sim 0.3 mas ) , indicating that the lens is very likely to be a planetary-mass object .
We conduct an extensive search for possible signatures of a companion star in the light curve of the event , finding no significant evidence for the putative host star .
For the first time , we also demonstrate that the angular Einstein radius of the lens does not depend on blending in the low-magnification events with strong finite source effects .