paper

Sharp Chandra View of ROSAT All-Sky Survey Bright Sources: I. Improvement of Positional Accuracy

arXiv:1608.03097 · doi:10.1088/1674-4527/16/12/187

Abstract

The ROSAT All-Sky Survey (RASS) represents one of the most complete and sensitive soft X-ray all-sky surveys to date. However, the deficient positional accuracy of the RASS Bright Source Catalog (BSC) and subsequent lack of firm optical identifications affect the multi-wavelength studies of X-ray sources. The widely used positional errors based on the Tycho Stars Catalog (Tycho-1) have previously been applied for identifying objects in the optical band. The considerably sharper Chandra view covers a fraction of RASS sources, whose could be improved by utilizing the sub-arcsec positional accuracy of Chandra observations. We cross-match X-ray objects between the BSC and \emph{Chandra} sources extracted from the Advanced CCD Imaging Spectrometer (ACIS) archival observations. A combined counterparts list (BSCxACIS) with \emph{Chandra} spatial positions weighted by the X-ray flux of multi-counterparts is employed to evaluate and improve the former identifications of BSC with the other surveys. Based on these identification evaluations, we suggest that the point-likeness of BSC sources and INS (isolated neutron stars) candidates should be carefully reconsidered.

arXiv comment13 pages, 8 figures and 3 tables, accepted by RAA

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