TITLE:
The Evolution QSOs—The Optical Luminosity Function
AUTHORS:
Irom Ablu Meitei, K. Yugindro Singh
KEYWORDS:
Galaxies; Active
JOURNAL NAME:
International Journal of Astronomy and Astrophysics,
Vol.3 No.2,
May
31,
2013
ABSTRACT:
Using the data of the 2
Degree Field (2dF) QSO Redshift Survey (2QZ) and the associated 6 Degree Field
(6dF) QSO Redshift Survey (6QZ) of the Anglo-Australian Telescope, a study of
the Optical Luminosity Function of Quasi Stellar Objects (QSOs) has been made
to understand the evolutionary scenario of QSOs. Different models for the QSO
evolution are studied. The two-power law model of the optical luminosity
function with second order polynomial evolution is found to fit best the
observed QSO optical luminosity function. We have also determined an improved
evolutionary model which fits better than the second order polynomial evolution
model. The best fit parameters for the observed optical luminosity
function have been determined using the Levenberg-Marquardt algorithm of
non-linear least square fit for a flat universe i.e., ΩΛ + Ωm = 1 and Ho =
70 km·s–1·Mpc–1. The observed slope
of the log N － m curve i.e., 1.10 ± 0.01 reveals that there
were more QSOs at larger distances (or look back times) than there are locally
which, in turn, indicates that the QSOs are evolving. The observed value of
V/Vmax>
is found to be greater than 0.5 for different values of the cosmological
constant which also hints strong evolution of the QSOs.