The stellar content of the XMM-Newton slew survey

Abstract

We present a detailed analysis of the stellar content of the current version of the XMM-Newton slew survey (XMMSL2). Since stars emit only a small fraction of their total luminosity in the X-ray band, the stellar XMMSL2 sources ought to have relatively bright optical counterparts. Therefore the stellar identifications are obtained by an automatic crossmatch of the XMMSL2 catalog with the first Gaia data release (Gaia DR1), the 2MASS and the Tycho2 catalogs. The reliability of this procedure is verified by a comparison with the individually classified Einstein Observatory medium sensitivity survey X-ray sources and by a crossmatch with the Chandra Source Catalog. We identify 6815 of the 23252 unique XMMSL2 sources to be stellar sources, while 893 sources are flagged as unreliable. For every counterpart a matching probability is estimated based upon the distance between the XMMSL2 source and the counterpart. Given this matching probability the sample is expected to be reliable to 96.7 % and complete to 96.3 %. The sample contains stars of all spectral types and luminosity classes, with late-type dwarfs having the largest share. For many stellar sources the fractional contribution of the X-ray band to the total energy output is found above the saturation limit of previous studies ($L_{\mathrm{X}}/L_{\mathrm{bol}}=10^{-3}$), because the XMMSL2 sources are more affected by flares due to their short exposure times of typically 6 s. A comparison with the "Second ROSAT all-sky survey (2RXS) source catalog" shows that about 25 % of the stellar XMMSL2 sources are previously unknown X-ray sources. The results of our identification procedure can be accessed via VizieR.

Accepted for publication in A&A

References in corpus (5)

• The Gaia mission
• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• Second ROSAT all-sky survey (2RXS) source catalogue
• The first XMM-Newton slew survey catalogue: XMMSL1
• Simultaneous optical and X-ray observations of a giant flare on the ultracool dwarf LP412-31

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• Counterpart identification and classification for eRASS1 and characterisation of the AGN content
• Radio Variable and Transient Sources on Minute Timescales in the ASKAP Pilot Surveys
• Dynamical masses for the Pleiades binary system HII-2147
• Populations of highly variable X-ray sources in the XMM$-$Newton slew survey
• The high-energy environment of the heavy sub-Earth GJ 367 b indicates likely complete evaporation of its atmosphere
• HD 63021: Chromospheric Activity and Mass Transfer in a Close Binary
• The stellar population in the SARAO MeerKAT Galactic Plane Survey
• An expanded ultraluminous X-ray source catalogue