2023/06/29 by Cho, Hojin, Woo, Jong-Hak, Wang, Shu +29 · 7 citations
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2306.16683
The broad line region (BLR) size-luminosity relation has paramount importance for estimating the mass of black holes in active galactic nuclei (AGNs). Traditionally, the size of the Hβ BLR is often estimated from the optical continuum luminosity at 5100\angstrom , while the size of the Hα BLR and its correlation with the luminosity is much less constrained. As a part of the Seoul National University AGN Monitoring Project (SAMP) which provides six-year photometric and spectroscopic monitoring data, we present our measurements of the Hα lags of 6 high-luminosity AGNs. Combined with the measurements for 42 AGNs from the literature, we derive the size-luminosity relations of Hα BLR against broad Hα and 5100\angstrom continuum luminosities. We find the slope of the relations to be 0.61±0.04 and 0.59±0.04, respectively, which are consistent with the \hb size-luminosity relation. Moreover, we find a linear relation between the 5100\angstrom continuum luminosity and the broad Hα luminosity across 7 orders of magnitude. Using these results, we propose a new virial mass estimator based on the Hα broad emission line, finding that the previous mass estimates based on the scaling relations in the literature are overestimated by up to 0.7 dex at masses lower than 107~M\odot.