Bayesian timing analysis of giant flare of SGR 1806-20 by RXTE PCA

TL;DR

This paper applies Bayesian timing analysis to RXTE data of SGR 1806-20's giant flare, detecting known and new QPO frequencies to constrain the neutron star's equation of state.

Contribution

It introduces a Bayesian method to identify transient oscillations in giant flare data, revealing new QPO frequencies consistent with theoretical models.

Findings

Detected multiple QPO frequencies, including new ones.

Confirmed frequencies predicted by theoretical models.

Provided constraints on the neutron star's equation of state.

Abstract

By detecting high frequency quasi-periodic oscillations (QPOs) and estimating frequencies of them 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. 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 a Bayesian periodicity detection method (Gregory & Loredo, 1992) for the search of oscillations of transient nature. 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 oscillations predicted by Colaiuda et al. (2009) based on the APR_{14} EoS (Akmal et al., 1998) for SGR 1806-20.