A systematic cross-search for radio/infrared counterparts of XMM- Newton sources

COMBI, J. A.; ALBACETE COLOMBO, J. F.; PELLIZA, L.; LÓPEZ-SANTIAGO, J.; ROMERO, G. E.; MARTÍ, J; MUÑOZ-ARJONILLA, A.J.; SÁNCHEZ-AYASO, E.; LUQUE-ESCAMILLA, L. P.; SÁNCHEZ-SUTIL, J.R.; COMBI, J. A.; ALBACETE COLOMBO, J. F.; PELLIZA, L.; LÓPEZ-SANTIAGO, J.; ROMERO, G. E.; MARTÍ, J; MUÑOZ-ARJONILLA, A.J.; SÁNCHEZ-AYASO, E.; LUQUE-ESCAMILLA, L. P.; SÁNCHEZ-SUTIL, J.R.

ASTROPHYSICS AND SPACE SCIENCE

SPRINGER

Lugar: Berlin; Año: 2011 vol. 331 p. 53 - 61

0004-640X

We present a catalog of cross-correlated radio, infrared and X-ray sources using a very restrictive selection criteria with an IDL-based code developed by us. The significance of the observed coincidences was evaluated through Monte Carlo simulations of synthetic sources following a well-tested protocol. We found 3320 coincident radio/X-ray sources with a high statistical significance characterized by the sum of error-weighted coordinate differences. For 997 of them, 2MASS counterparts were found. The percentage of chance coincidences is less than 1%. X-ray hardness ratios of well-known populations of objects were used to provide a crude representation of their X-ray spectrum and to make a preliminary diagnosis of the possible nature of unidentified X-ray sources. The results support the fact that the X-ray sky is largely dominated by Active Galactic Nuclei at high galactic latitudes (| b|≥10°). At low galactic latitudes (| b|≤10°) most of unidentified X-ray sources (?94%) lie at | b|≤2°. This result suggests that most of the unidentified sources found toward the Milky Way plane are galactic objects. Well-known and unidentified sources were classified in different tables with their corresponding radio/infrared and X-ray properties. These tables are intended as a useful tool for researchers interested in particular identifications.