A Comprehensive Study of Pulse Profile Evolution in SGR 1806-20 and SGR 1900+14 with the Rossi X-Ray Timing Explorer Proportional Counter Array

Soft Gamma Repeaters undergo pulse profile changes in connection with the burst activity. Here we construct a comprehensive pulse profile history of SGR 1806-20 and SGR 1900+14 in different energy bands using Rossi X-ray Timing Explorer/Proportional Counter Array observations. We quantify the pulse profile evolution using the Fourier harmonic powers of profiles. Moreover, we determined the RMS pulsed count rates (PCRs) of each profile. We show that the pulse profiles SGR 1806$-$20 remain as single pulsed while those of SGR 1900+14 alter remarkable in all energy bands. Highly significant pulsations form SGR 1900+14 following August 27 and April 19 bursts enabled us to study not only decay of PCRs in different energy bands and also their correlations with one another.