Pu, X (reprint author), Nanjing Normal Univ, Dept Phys, Nanjing 210097, Peoples R China.
Using 7.5-yr spectroscopic monitoring data of a sample of 17 Palomar-Green quasi-stellar objects (PG QSOs) (z = 0.061-0.371), we obtain the optical spectral slope for each object at all epochs by a power-law fit to the spectra in continuum bands. All of these 17 PG QSOs exhibit obvious spectral-slope variability. Most of the 17 objects show anticorrelation between the spectral slope and the rest-frame 5100-angstrom continuum flux, while five of them exhibit strong anticorrelation (correlation coefficient R larger than 0.5). For the ensemble of these 17 PG QSOs, a strong anticorrelation between the average spectral slope and the average rest-frame 5100-angstrom luminosity is found, while no correlation is found between the spectral slope and the Eddington ratio. A median anticorrelation between spectral-slope changes and continuum-flux variations is also found which indicates a hardening of the spectrum during bright phases. Accretion disc (jet) instability models with other mechanisms associated with changes in the accretion processes are promising.
Pu, X,Bian WH,Bian, W,et al. The relation between the optical spectral slope and the luminosity for 17 Palomar-Green quasi-stellar objects[J]. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,2006,372(1):#REF!.
Pu, X,卞维豪,Bian, W,&Huang, K.(2006).The relation between the optical spectral slope and the luminosity for 17 Palomar-Green quasi-stellar objects.MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY,372(1),#REF!.
Pu, X,et al."The relation between the optical spectral slope and the luminosity for 17 Palomar-Green quasi-stellar objects".MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY 372.1(2006):#REF!.