Discovery of a 30 day period in the supergiant fast X-ray transient SAX J1818.6-1703

TL;DR

This paper reports the discovery of a 30-day periodic outburst cycle in the supergiant fast X-ray transient SAX J1818.6-1703, revealing a regular pattern in its high-energy emissions.

Contribution

The study identifies a previously unknown 30-day periodicity in SAX J1818.6-1703, providing new insights into the behavior of supergiant fast X-ray transients.

Findings

SAX J1818.6-1703 exhibits a 30-day emission period.

It is the second SFXT with a confirmed periodic outburst.

The period is shorter than that of IGR J11215-5952.

Abstract

SAX J1818.6-1703 has been characterised as a Supergiant Fast X-ray Transient system on the basis of several INTEGRAL/IBIS detections since the original BeppoSAX Wide Field Camera detection. Using IBIS/ISGRI, Swift/BAT and archival observations, we show that in fact SAX J1818.6-1703 exhibits emission on a period of 30 +/- 0.1 days, with a high degree of recurrence. SAX J1818.6-1703 is therefore the second SFXT shown to exhibit periodic outbursts, but with a considerably shorter period than the other known system, IGR J11215-5952.