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 Q...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.展开更多
A study of the optical luminosity function of Quasi Stellar Objects (QSOs) and its evolution with redshift is carried out using the data from the Sloan Digital Sky Survey Data Release Seven (SDSS DR7). It is shown tha...A study of the optical luminosity function of Quasi Stellar Objects (QSOs) and its evolution with redshift is carried out using the data from the Sloan Digital Sky Survey Data Release Seven (SDSS DR7). It is shown that the observed QSO luminosity function is well fitted by a Schechter function model of the form , where is the break or characteristic luminosity with luminosity evolution characterized by a second order polynomial in red shift. The best fit parameters are determined by using the Levenberg-Marquardt method of nonlinear least square fit.展开更多
文摘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.
文摘A study of the optical luminosity function of Quasi Stellar Objects (QSOs) and its evolution with redshift is carried out using the data from the Sloan Digital Sky Survey Data Release Seven (SDSS DR7). It is shown that the observed QSO luminosity function is well fitted by a Schechter function model of the form , where is the break or characteristic luminosity with luminosity evolution characterized by a second order polynomial in red shift. The best fit parameters are determined by using the Levenberg-Marquardt method of nonlinear least square fit.
