| Description |
Quasars are supermassive black holes known to drive galaxy formation. They can have masses up to 109 solar masses and are the most luminous known objects in the sky, making them very important trackers of cosmic evolution. Given the large amount of research already surrounding quasar astrophysics, there still remains a great deal of uncertainty in the modeling of quasar spectra, origins of diversity, and spectroscopic signature of variability. Much of this uncertainty is associated with technical challenges in decoupling the effects of separate physical parameters, namely luminosity, mass accretion rate, black hole mass, and orientation. This research uses multiple epochs of spectra of single quasars to explore spectral variation of quasars with respect to luminosity (and thus the mass accretion rate) at a fixed redshift, orientation, and black hole mass. Using approximately 50 epochs of 328 different quasars fromthe Sloan Digital Sky Survey Reverberation Mapping Project, a high signal-to-noise composite differential spectrum is generated to represent the partial derivative of flux with respect to luminosity averaged over the full sample. The well-known anti-correlation between equivalent width of emission lines and luminosity is confirmed, but results unveil a surprising relationship between intrinsic changes of luminosity and quasars' spectral index. Jack-knife tests with respect to luminosity, redshift, spectral index, and the CIV FWHM are employed to explore this trend further, and directions for further research are discussed. |
