On the unified scheme for high-excitation galaxies and quasars in 3CRR sample

• Published in: Journal of astrophysics and astronomy Vol. 40; no. 1; pp. 1 - 9
• Main Authors: Odo, F. C., Okobi, P. E., Alhassan, J. A., Ubachukwu, A. A.
• Format: Journal Article
• Language: English
• Published: New Delhi Springer India 01-02-2019; Springer Nature B.V
• Subjects: Astronomy; Astrophysics and Astroparticles; Cosmology; Evolution; Excitation; Galactic evolution; Galaxies; Luminosity; Observations and Techniques; Orientation effects; Outflow; Physics; Physics and Astronomy; Quasars; Radio galaxies; general; Galaxies: active; galaxies: quasars
• DOI: 10.1007/s12036-018-9572-z
• EISSN: 0973-7758
• ISSN: 0250-6335

In this paper, we use the distributions of luminosity (
P
) and radio size (
D
) to re-examine the consistency of the unified scheme of high-excitation radio galaxies and quasars in the recently updated 3CRR sample. Based on a standard cosmology, we derive theoretically and show from observed data, the luminosity limit above which the 3CRR objects are well-sampled. We find, on average, a quasar fraction
∼
0.44 and galaxy-to-quasar size ratio
≈
2. Assuming a relativistic outflow of jet materials, we find a mean angle to the line of sight in the range
35
∘
≤
ϕ
≤
44
∘
for the quasars. On supposition of luminosity and orientation-dependent linear size evolution, expressed in a general functional form
D
(
P
,
z
,
ϕ
)
≈
P
±
q
(1+
z
)
-
w
sin
ϕ
, we show that above the flux detection threshold of the 3CRR sample, high-excitation galaxies and quasars undergo similar evolution with
q
=
-
0.5
;
w
=
-
0.27
and luminosity independent evolution parameter
x
=
2.27
, when orientation effect is accounted for. The results are consistent with orientation-based unified scheme for radio galaxies and quasars.