Open AccessThe XMM–Newton /2dF survey – V. The radio properties of the X‐ray population
Author(s) -
Georgakakis A.,
Georgantopoulos I.,
Leonidaki I.,
Akylas A.,
Stewart G. C.,
Goudis C.
Publication year - 2004
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2004.07991.x
Subject(s) - physics , astrophysics , luminosity , sky , active galactic nucleus , galaxy , radio galaxy , redshift , astronomy , spectral line , x shaped radio galaxy , x ray , population , optics , demography , sociology
In this paper, we cross‐correlate the FIRST (Faint Images of the Radio Sky at Twenty centimeters) 1.4‐GHz radio survey with a wide‐field (1.6 deg 2 ) shallow [ f X (0.5 − 8 keV) ≈ 10 −14 erg s −1 ] XMM–Newton survey. We find 12 X‐ray/radio matches representing 4 per cent of the X‐ray‐selected sample. Most of them are found to be associated with active galactic nuclei (a total of nine) on the basis of the observed optical spectra (three), radio morphology (two) or X‐ray/optical properties (four), whereas one radio source is identified with an X‐ray‐selected cluster. We also find two sources associated with low‐redshift galaxies with narrow emission line optical spectra, X‐ray luminosity L X (0.5 − 8 keV) ≈ 10 41 erg s −1 , radio luminosity density L 1.4 GHz ≈ 5 × 10 22 W Hz −1 and log f X / f opt ≈−2 , suggesting ‘normal’ star‐forming galaxies. We argue that radio surveys combined with X‐ray samples could provide a powerful tool for identifying X‐ray‐selected ‘normal’ galaxies powered by stellar processes. Finally, radio‐loud and radio‐quiet systems in the present sample have mean X‐ray spectral properties consistent with Γ≈ 1.9 .