The Accuracy of Cross-Correlation Estimates of Quasar Emission-Line Region Sizes
Abstract
The use of cross-correlation analyses of emission-line and optical continuum fluxes to determine broad-line region (BLR) sizes in low-luminosity quasars is examined in detail. Uncertainties associated with this method are discussed, and analytic formulas for estimating errors and determining confidence levels are presented. It is pointed out that systematic correlated errors between continuum and line fluxes are particularly dangerous and can lead to BLR sizes that may be too small. The results of some Monte Carlo simulations which are matched as closely as possible to real situations are presented. They indicate that the very small BLR size estimated by the cross-correlation method is not highly reliable.
- Publication:
-
The Astrophysical Journal Supplement Series
- Pub Date:
- September 1987
- DOI:
- 10.1086/191216
- Bibcode:
- 1987ApJS...65....1G
- Keywords:
-
- Emission Spectra;
- Quasars;
- Radio Sources (Astronomy);
- Seyfert Galaxies;
- Accuracy;
- Continuous Spectra;
- Cross Correlation;
- Error Analysis;
- Light Curve;
- Line Spectra;
- Monte Carlo Method;
- Astrophysics;
- GALAXIES: SEYFERT;
- NUMERICAL METHODS;
- QUASARS;
- RADIO SOURCES: VARIABLE