We observed the L4 Jupiter Trojans ( L4 JTs ) swarm using the Hyper Suprime-Cam attached to the 8.2 m Subaru telescope on March 30 , 2015 ( UT ) .
The survey covered \sim 26 deg ^ { 2 } of sky area near the opposition and around the ecliptic plane with the 240-sec exposure time in the r -band filter through the entire survey .
We detected 631 L4 JTs in the survey field with the detection limit of m _ { r } = 24.4 mag .
We selected 481 objects with absolute magnitude H _ { r } < 17.4 mag and heliocentric distance r < 5.5 au as an unbiased sample and then used them to estimate the size distribution .
Assuming a geometric albedo of 0.07 \citep grav12 , the size range of our unbiased sample is \sim 2 – 20 km in diameter ( D ) .
We can fit a single-slope power law to the cumulative size distribution and then found the best-fit index ( b ) is b = 1.84 \pm 0.05 in N ( > D ) ~ { } \propto~ { } D ^ { - b } .
The slope value ( \alpha ) of corresponding absolute magnitude distribution ( N ( H ) ~ { } \propto~ { } 10 ^ { \alpha H } ) is 0.37 \pm 0.01 .
This \alpha is consistent with that of the faint end slope presented by [ Wong & Brown ( 2015 ) ] .
The size distribution obtained from this survey is slightly different from previous survey ’ s result with a similar size range \citep *YN05 , YN08 , WB15 , which reported a broken power-law or double power-law slopes in their cumulative size distribution .
Our results insists that the slope of b = 1.84 continues from H = 14.0 to at least H = 17.4 .
Since this work contains the largest L4 JT samples and one magnitude deeper than the study by [ Wong & Brown ( 2015 ) ] , we believe that our study obtained the robustest size distribution of small JTs so far .
Combining the cataloged L4 JTs and our survey , we finally show the entire size distribution of L4 JTs up to H _ { r } = 17.4 mag .