Skip to main content# Calculating the Mass of Black Holes in Quasars in Order to Study the CIV Emission Line Variance

Presentation #532.03 in the session “AGN 2”.

Published onJan 11, 2021

Calculating the Mass of Black Holes in Quasars in Order to Study the CIV Emission Line Variance

This research studies the variance of the CIV and MgII emission lines in 109,523 quasars found in the Sloan Digital Sky Survey (SDSS). Specifically, we want to study the CIV emission line and how the line shift varies over time compared to the stable MgII line. Studying this variation can tell us if using the CIV emission line is a good or bad candidate to measure the mass of the black holes found in quasars. These quasars are selected because they are of high quality and within a redshift range of 1.7 < z < 2.6. To correct the continuum, we follow similar methods to Shen et al. (2011) by accounting for dust, iron emissions, and continuum subtraction. To account for dust, we first deredden the flux by using dust maps from Schlegel et al. (1998). To subtract out the iron emissions and continuum, we use the iron template from Vestergard et al. (2001) and line fitting techniques. Lastly, we fit Gaussian curves to the CIV and MgII emission lines in order to calculate their covariance matrices and center line (μ) values. For the CIV, we fit three different Gaussians, and for MgII, we only fit one. To find the mass of the black hole, we use the virial black hole mass equation found in Shen et al. (2011). We can compare the black hole masses that we will calculate for both the MgII and CIV and make final conclusions on the reliability of the CIV emission line.