On the Absence of Core Luminosity–Core-Dominance Parameter (PC − R) Correlation in Radio Galaxies and BL Lacs

• Published in: Journal of astrophysics and astronomy Vol. 34; no. 1; pp. 61 - 67
• Main Authors: ALHASSAN, J. A., UBACHUKWU, A. A., ODO, F. C.
• Format: Journal Article
• Language: English
• Published: India Springer-Verlag 01-03-2013; Springer Nature B.V
• Subjects: Astronomy; Astrophysics; Astrophysics and Astroparticles; Correlation analysis; Luminosity; Observations and Techniques; Physics; Physics and Astronomy; Radio astronomy; Stars & galaxies; Seyfert—galaxies; jets; general-quasars—galaxies; BL Lacertae objects
• ISSN: 0250-6335; 0973-7758
• DOI: 10.1007/s12036-013-9161-0

We have presented an alternative interpretation for the absence of correlation in the relationship between the core radio power (
P
C
) and core-dominance parameter (
R
) for a sample of BL Lacs and radio galaxies found in Fan & Zhang (
Astron. Astrophys.
407
, 899 (
2003
)). This is contrary to the predictions of the relativistic beaming and radio source orientation models in which the core luminosity is expected to be Doppler-boosted relative to the extended luminosity which is generally assumed to be isotropic. Our analysis of the
P
C
 − 
R
data indicates a strong luminosity selection effect (reminiscent of bright source samples due to Malmquist bias) in the sample. In particular, we showed that a strong
P
C
 − 
R
correlation exists above some redshift cut-off which may correspond to the flux limit of the sample used.