Millisecond dips in the RXTE/PCA light curve of Sco X-1 and TNO occultation

Abstract

Millisecond dips in the RXTE/PCA light curve of Sco X-1 were reported recently (Chang et al. 2006), which were interpreted as the occultation of X-rays from Sco X-1 caused by Trans-Neptunian Objects (TNO) of hundred-meter size. Inconclusive signatures of possible instrumental effects in many of these dip events related to high-energy cosmic rays were later found (Jones et al. 2006) and the TNO interpretation became shaky. Here we report more detailed analysis aiming at distinguishing true occultation events from those related to cosmic rays. Based on some indicative criteria derived from housekeeping data and two-channel spectral information, we suggest that about 10% of the dips are probable events of occultation. The total number of TNOs of size from 60 m to 100 m is estiamted to be about 10^{15} accordingly. Limited by the coarser time resolution of standard data modes of RXTE/PCA, however, definite results cannot be obtained. Adequately configured observations with RXTE or other new instruments in the future are very much desired.

arXiv comment12 pages (including 14 figures), submitted to MNRAS

References in corpus (9)

• Calibration of the Rossi X-ray Timing Explorer Proportional Counter Array
• The Size Distribution of Trans-Neptunian Bodies
• In-flight Performance of the High Energy X-ray Timing Experiment on the Rossi X-ray Timing Explorer
• Properties of the Trans-Neptunian Belt: Statistics From the CFHT Survey
• The Size Distribution of Kuiper Belt Objects
• Planet Formation in the Outer Solar System
• Physical changes during Z-track movement in Sco X-1 on the flaring branch
• Occultation Searches for Kuiper Belt Objects
• Millisecond Dips in Sco X-1 are Likely the Result of High-Energy Particle Events

Cited by in corpus (16)

• A single sub-km Kuiper Belt object from a stellar Occultation in archival data
• Detectability of Occultation of Stars by Objects in the Kuiper Belt and Oort Cloud
• The TAOS Project: Results From Seven Years of Survey Data
• A Search for Occultations of Bright Stars by Small Kuiper Belt Objects using Megacam on the MMT
• The TAOS Project: Upper Bounds on the Population of Small KBOs and Tests of Models of Formation and Evolution of the Outer Solar System
• The Taiwanese-American Occultation Survey: The Multi-Telescope Robotic Observatory
• First Results From The Taiwanese-American Occultation Survey (TAOS)
• Millisecond dip events in the 2007 RXTE/PCA data of Sco X-1 and the TNO size distribution
• Production of Millisecond Dips in Sco X-1 Count Rates by Dead Time Effects
• Formation and Collisional Evolution of Kuiper Belt Objects
• Millisecond dips in the 2007-2009 RXTE/PCA lightcurve of Sco X-1 and one possible occultation event
• Search for serendipitous TNO occultation in X-rays
• On the Use of Cherenkov Telescopes for Outer Solar System Body Occultations
• Detectability of Oort cloud objects using Kepler
• A Bayesian approach to the analysis of time symmetry in light curves: Reconsidering Scorpius X-1 occultations
• Upper limits to the number of Oort Cloud Objects based on serendipitous occultation events search in X-rays