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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

SPECTRAL EVOLUTION IN HIGH REDSHIFT QUASARS FROM THE FINAL BARYON OSCILLATION SPECTROSCOPIC SURVEY SAMPLE

Jensen, Trey W., Vivek, M., Dawson, Kyle S., Anderson, Scott F., Bautista, Julian, Bizyaev, Dmitry, Brandt, William N., Brownstein, Joel R., Green, Paul, Harris, David W., Kamble, Vikrant, McGreer, Ian D., Merloni, Andrea, Myers, Adam, Oravetz, Daniel, Pan, Kaike, Pâris, Isabelle, Schneider, Donald P., Simmons, Audrey, Suzuki, Nao 19 December 2016 (has links)
We report on the diversity in quasar spectra from the Baryon Oscillation Spectroscopic Survey. After filtering the spectra to mitigate selection effects and Malmquist bias associated with a nearly flux-limited sample, we create high signal-to-noise ratio composite spectra from 58,656 quasars (2.1 <= z <= 3.5), binned by luminosity, spectral index, and redshift. With these composite spectra, we confirm the traditional Baldwin effect (BE, i. e., the anticorrelation of C IV equivalent width ( EW) and luminosity) that follows the relation W-lambda alpha L-beta w with slope beta(w) = -0.35 +/- 0.004, -0.35 +/- 0.005, and -0.41 +/- 0.005 for z. =. 2.25, 2.46, and 2.84, respectively. In addition to the redshift evolution in the slope of the BE, we find redshift evolution in average quasar spectral features at fixed luminosity. The spectroscopic signature of the redshift evolution is correlated at 98% with the signature of varying luminosity, indicating that they arise from the same physical mechanism. At a fixed luminosity, the average C IV FWHM decreases with increasing redshift and is anti-correlated with C IV EW. The spectroscopic signature associated with C IV FWHM suggests that the trends in luminosity and redshift are likely caused by a superposition of effects that are related to black hole mass and Eddington ratio. The redshift evolution is the consequence of a changing balance between these two quantities as quasars evolve toward a population with lower typical accretion rates at a given black hole mass.

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