Search for Intermittent X-ray Pulsations from Neutron Stars in Low Mass X-ray Binaries

TL;DR

This study searched for and identified weak and strong coherent X-ray pulsations in 13 low mass X-ray binaries, revealing new pulsation episodes and improving understanding of neutron star behavior in binary systems.

Contribution

The paper introduces a novel binary orbital motion correction method to detect weak pulsations in LMXBs, uncovering new pulsation episodes and enhancing pulsation detection techniques.

Findings

75 pulsation episodes with weak but coherent pulsations identified

8 new episodes with relatively strong pulsations discovered

Improved detection of pulsations by correcting for binary orbital motion

Abstract

We present the results of our extensive binary orbital motion corrected pulsation search for 13 low mass X-ray binaries (LMXBs). These selected sources exhibit burst oscillations in X-rays with frequencies ranging from 45 to 1122 Hz, and have a binary orbital period varying from 2.1 to 18.9 hours. We first determined episodes that contain weak pulsations around the burst oscillation frequency by searching all archival Rossi X-ray Timing Explorer (RXTE) data of these sources. Then, we applied Doppler corrections to these pulsation episodes to discard the smearing effect of the binary orbital motion and searched for recovered pulsations at the second stage. Here we report 75 pulsation episodes that contain weak but coherent pulsations around the burst oscillation frequency. Furthermore, we report eight new episodes that show relatively strong pulsations in the binary orbital motion corrected data.