Production of Millisecond Dips in Sco X-1 Count Rates by Dead Time Effects

TL;DR

This paper demonstrates that millisecond dips in Sco X-1 count rates are caused by detector dead time effects from high-energy particles, not by occultations by trans-Neptunian objects, challenging previous claims.

Contribution

It provides evidence that the observed dips are due to detector effects rather than astronomical occultations, clarifying the origin of these signals.

Findings

Most dips are caused by detector dead time effects.

Less than 10% of dips could be due to TNO occultations.

No conclusive evidence supports TNO occultations in the data.

Abstract

Chang et al. (2006) reported millisecond duration dips in the X-ray intensity of Sco X-1 and attributed them to occultations of the source by small trans-Neptunian objects (TNOs). We have found multiple lines of evidence that these dips are not astronomical in origin, but rather the result of high-energy charged particle events in the RXTE PCA detectors. Our analysis of the RXTE data indicates that at most 10% of the observed dips in Sco X-1 could be due to occultations by TNOs, and, furthermore, we find no positive or supporting evidence for any of them being due to TNOs. We therefore believe that it is a mistake to conclude that any TNOs have been detected via occultation of Sco X-1.