2003MNRAS.342..575C -
Mon. Not. R. Astron. Soc., 342, 575-586 (2003/June-3)
The BeppoSAX High Energy Large Area Survey (HELLAS) - VI. The radio properties.
CILIEGI P., VIGNALI C., COMASTRI A., FIORE F., LA FRANCA F. and PEROLA G.C.
Abstract (from CDS):
We present results of a complete radio follow-up obtained with the VLA and ATCA radio telescopes down to a 6-cm flux limit of about 0.3 mJy (3σ) of all the 147 X-ray sources detected in the BeppoSAX HELLAS survey. We found 53 X-ray/radio likely associations, corresponding to about one-third of the X-ray sample. Using the two-point spectral index αro= 0.35 we divided all the HELLAS X-ray sources into radio-quiet and radio-loud. We have 26 sources classified as radio-loud objects, corresponding to ∼18 per cent of the HELLAS sample. In agreement with previous results, the identified radio-loud sources are associated mainly with Type 1 active galactic nuclei (AGNs) with L5–10keV≳1044 erg/s, while all the identified Type 2 AGNs and emission-line galaxies are radio-quiet objects with L5–10keV ≲ 1044 erg/s. The analysis of the radio spectral index suggests that Type 1 AGNs have a mean radio spectral index (<αAGN1 >= 0.25±0.1) flatter than Type 2 AGNs and emission-line galaxies (<αAGN2>= 0.69±0.11). This result is in agreement with the idea that the core-dominated radio emission from Type 1 AGNs is self-absorbed, while in Type 2 AGNs and emission-line galaxies the radio emission takes place on larger physical scale, without self-absorption.
Abstract Copyright:
2003 RAS
Journal keyword(s):
surveys - quasars: general - radio continuum: galaxies
VizieR on-line data:
<Available at CDS (J/MNRAS/342/575): table1.dat>
Simbad objects:
150
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