Tsing Hua Univ, Ctr Astrophys, Dept Engn & Phys, Beijing 100084, Peoples R China
; Tsing Hua Univ, Ctr Astrophys, Dept Phys, Beijing 100084, Peoples R China
; Chinese Acad Sci, Inst High Energy Phys, Lab Particle Astrophys, Beijing 100039, Peoples R China
; Univ Alabama, Dept Phys, Huntsville, AL 35899 USA
; NASA, George C Marshall Space Flight Ctr, Space Sci Lab, Huntsville, AL 35812 USA
A statistic, w, the differential coefficient of the mean absolute difference of an observed light curve, is proposed for timescale analysis of shot widths. The shortest width of random shots can be measured by the position of the lower cutoff in the timescale spectrum of w. We use the statistic to analyze X-ray light curves from a sample of neutron star and black hole binaries, and the results show that the timescale analysis can help us distinguish between neutron star binaries and black hole binaries. The analysis can further reveal the structure and dynamics of accretion disks around black holes.