2007/01/30 by Hsiang‐Kuang Chang, Hsiang-Kuang Chang, J.M. Liang +4 · 2 citations
Physics and Astronomy · #Astro and Planetary Science #Astronomy #Astrophysics #Light curve #Millisecond #Occultation #Physics #Solar and Space Plasma Dynamics #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1111/j.1365-2966.2007.11729.x
published as Mon.Not.Roy.Astron.Soc.378:1287,2007 · 12 pages (including 14 figures), submitted to MNRAS
arxiv created 2007/01/30 · openalex publication_date 2007/06/16 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Millisecond dips in the RXTE/Proportional Counter Array (PCA) light curve of Sco X-1 were reported recently, which were interpreted as the occultation of X-rays from Sco X-1 caused by trans-Neptunian objects (TNO) of 100-m size. Inconclusive signatures of possible instrumental effects in many of these dip events related to high-energy cosmic rays were later found 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 per cent of the dips are probable events of occultation. The total number of TNOs of size from 60 to 100 m is estimated to be about 1015 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.