X-ray Pulsations from the region of the Supergiant Fast X-ray Transient IGR J17544-2619

TL;DR

This study reports the detection of a 71.49-second X-ray pulsation from the supergiant fast X-ray transient IGR J17544-2619, suggesting the presence of a neutron star and expanding the understanding of HMXB classifications.

Contribution

First detection of X-ray pulsations from IGR J17544-2619, indicating a neutron star and highlighting the diversity of supergiant fast X-ray transients in HMXB classifications.

Findings

Detected a 71.49 s X-ray pulsation from IGR J17544-2619.

Placed the system within the wind-fed supergiant XRB region on the Corbet diagram.

Shows SFXTs span across traditional HMXB classes.

Abstract

Phase-targeted RXTE observations have allowed us to detect a transient 71.49 \pm 0.02 s signal that is most likely to be originating from the supergiant fast X-ray transient IGR J17544-2619. The phase-folded light curve shows a possible double-peaked structure with a pulsed flux of ~4.8*10^-12 erg cm^-2 s^-1 (3-10 keV). Assuming the signal to indicate the spin period of the neutron star in the system, the provisional location of IGR J17544-2619 on the Corbet diagram places the system within the classical wind-fed supergiant XRB region. Such a result illustrates the growing trend of supergiant fast X-ray transients to span across both of the original classes of HMXB in Porb - Pspin space.