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

¹ Astrophysikalisches Institut und Universitäts-Sternwarte, Universität Jena, 07745 Jena, Germany
e-mail: vvh@astro.uni-jena.de
² Theoretical Astrophysics, Eberhard-Karls-Universität Tübingen, 72076 Tübingen, Germany

Received: 24 June 2010
Accepted: 26 December 2010

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 APR₁₄ EoS for SGR  1806−20.