Search for serendipitous TNO occultation in X-rays

TL;DR

This study searches for occultations of X-ray sources by small Trans-Neptunian Objects in the outer solar system using RXTE data, setting upper limits on TNO sizes between 30m and 300m.

Contribution

It reports the first X-ray occultation search for TNOs, analyzing RXTE data to constrain TNO size distribution and proposing future observational strategies.

Findings

No definite TNO occultation events detected

Set upper limits on TNO sizes from 30m to 300m

Identified X-ray sources suitable for future observations

Abstract

To study the population properties of small, remote objects beyond Neptune's orbit in the outer solar system, of kilometer size or smaller, serendipitous occultation search is so far the only way. For hectometer-sized Trans-Neptunian Objects (TNOs), optical shadows actually disappear because of diffraction. Observations at shorter wave lengths are needed. Here we report the effort of TNO occultation search in X-rays using RXTE/PCA data of Sco X-1 taken from June 2007 to October 2011. No definite TNO occultation events were found in the 334 ks data. We investigate the detection efficiency dependence on the TNO size to better define the sensible size range of our approach and suggest upper limits to the TNO size distribution in the size range from 30 m to 300 m. A list of X-ray sources suitable for future larger facilities to observe is proposed.