2004/03/10 by Xue-Bing Wu, Rui Wang, R. Wang +3 · 9 citations
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Black hole (networking) #Blazar #Emission spectrum #Galaxy #Gamma ray #Gamma-ray bursts and supernovae #Line (geometry) #Luminosity #Physics #Quasar #Reverberation mapping #Spectral line #astro-ph
paper · pdf · doi:10.1051/0004-6361:20035845
published as Astron.Astrophys. 424 (2004) 793-798 · 7 pages, accepted for publication in Astronomy & Astrophysics
arxiv created 2004/03/10 · openalex publication_date 2004/09/01 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
An empirical relation between the broad line region (BLR) size and optical continuum luminosity is often adopted to estimate the BLR size and then the black hole mass of AGNs. However, optical luminosity may not be a good indicator of photoionizing luminosity for extremely radio-loud AGNs because the jets usually contribute significantly to the optical continuum. Therefore, the black hole masses derived for blazar-type AGNs with this method are probably overestimated. Here we first derived a tight empirical relation between the BLR size and the Hβ emission line luminosity, ergs s, from a sample of 34 AGNs with the BLR size estimated with the reverberation mapping technique. Then we applied this relation to estimate the black hole masses of some AGNs and found that for many extremely radio-loud AGNs the black hole masses obtained with the relation are systematically lower than those derived previously with the relation, while for radio-quiet and slightly radio-loud AGNs the results obtained with these two methods are almost the same. The difference of black hole masses estimated with these two relations increases with the radio-loudness for extremely radio-loud AGNs, which is consistent with the fact that their equivalent widths of the H emission line become smaller at greater radio-loudness. If the small H equivalent widths of extremely radio-loud AGNs are indeed caused by the beaming effect, we argue that the optical emission line luminosity may be a better tracer of ionizing luminosity for blazar-type AGNs and the black hole masses derived with the relation are probably more accurate.