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Title: The optical variability of SDSS quasars from multi-epoch spectroscopy. I. Results from 60 quasars with ≥ six-epoch spectra

In a sample of 60 quasars selected from the Sloan Digital Sky Survey with at least six-epoch spectroscopy, we investigate the variability of emission lines and continuum luminosity at various aspects. A strong anti-correlation between the variability and continuum luminosity at 2500 Å is found for the sample, which is consistent with previous works. In individual sources, we find that half of the sample objects follow the trend of being bluer when brighter, while the remaining half follow the redder-when-brighter (RWB) trend. Although the mechanism for RWB is unclear, the effects of host galaxy contribution due to seeing variations cannot be completely ruled out. As expected from the photoionization model, the positive correlations between the broad emission line and continuum luminosity are found in most individual sources, as well as for the whole sample. We confirm the Baldwin effect in most individual objects and the whole sample, while a negative Baldwin effect is also found in several quasars, which can be at least partly (if not all) due to the host galaxy contamination. We find positive correlations between the broad emission line luminosity and line width in most individual quasars, as well as the whole sample, implying a line basemore » that is more variable than the line core.« less
Authors:
;  [1]
  1. Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)
Publication Date:
OSTI Identifier:
22365217
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 792; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CORRELATIONS; EMISSION; GALAXIES; LINE WIDTHS; LUMINOSITY; PHOTOIONIZATION; QUASARS; SPECTRA; SPECTROSCOPY; VARIATIONS