Bayesian timing analysis of giant flare of SGR 180620 by RXTE PCA

Abstract

Aims: By detecting high-frequency quasi-periodic oscillations (QPOs) and estimating their frequencies during the decaying tail of giant flares from soft gamma-ray repeaters (SGRs) useful constraints for the equation of state (EoS) of superdense matter may be obtained via comparison with theoretical predictions of eigenfrequencies. Methods: We used the data collected by the Rossi X-Ray Timing Explorer (RXTE/XTE) Proportional Counter Array (PCA) of a giant flare of SGR 1806-20 on 2004 Dec. 27 and applied an existing Bayesian periodicity detection method to search for oscillations of a transient nature. Results: In addition to the already detected frequencies, we found a few new frequencies (f QPOs ~ 16.9,21.4,36.4,59.0,116.3 Hz) of predicted oscillations based on the APR 14 EoS for SGR 1806-20.