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Updated: Jul 28, 2026

11:20
Investigation of Early Plasma Evolution Induced by Ultrashort Laser Pulses
Published on: July 2, 2012
Discovery of hidden blazars
1Prc-Mrc 2nd Floor/R9950, McDonald Observatory and Astronomy Department, University of Texas, Austin, TX 78712, USA. feng@astro.as.utexas.edu
Summary
Blazars may be detected by observing changes in emission line ratios, supporting a unified model for radio-loud quasars. This study found significant variations in quasar emission lines over a decade.
Area of Science:
- Astronomy
- Astrophysics
- Cosmology
Background:
- Radio-loud quasars are proposed to encompass blazar activity within a unified model.
- Observed differences in quasars are attributed to viewing angle variations.
- Blazars are hypothesized to exhibit detectable emission line ratio variations due to fluctuating illumination.
Purpose of the Study:
- To test the prediction that blazars can be identified via emission line ratio variations.
- To investigate quasar emission line variability over extended periods.
- To gather evidence supporting the unification scheme for radio-loud quasars.
Main Methods:
- Spectroscopic analysis of 62 quasars at redshift ~2.
- Comparison of emission line ratios (CIV/CIII], CIV/Lyalpha) with data from over 10 years prior.
- Search for significant (>20%) variations in spectral line ratios.
Main Results:
- Detected substantial (>20%) variations in emission line ratios, specifically CIV/CIII] and CIV/Lyalpha.
- Observed variations align with predictions based on variable illumination of gas clouds.
- The findings are consistent with the proposed unification scheme.
Conclusions:
- The observed emission line variations support the hypothesis for detecting blazars.
- The results provide strong evidence for the unification scheme of radio-loud quasars.
- Viewing angle is a key factor in the observed diversity of quasars.
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