Abstract
Abstract Scorpius X-1 (Sco X-1) is the brightest extra-solar X-ray source in the sky. We present the result of searches for the neutron star rotation period in the X-ray emission from Sco X-1. Although a rich spectrum of quasi-periodic pulsations has been found in Sco X-1,the rotation signature of its neutron star has been being missing. We conducted H-test and epoch-folding Chi-square test to investigate possible periodic signals of Sco X-1. The Obs. ID 94318 data we used were obtained by the Proportional Counter Array (PCA) on board the Rossi X-ray Timing Explorer (RXTE). The frequency range searched is from 250 Hz to 650 Hz with a step of 2×10^−5. The Fourier width of the data we used is 1.1×10^−4. We did not find significant enough periodicity in our analysis. The 2σ upper limit to the pulsed flux based on the observed H is 5.6×10−3 photons cm^−2 s^−1. The total flux is 5.0 photons cm^−2 s^−1 during the observation. The upper limit to the pulsed fraction is 1.1×10^−3.