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Black hole mass estimation using a relation between the BLR size and emission line luminosity of AGN
Wu, XB; Wang, R; Kong, MZ; Liu, FK; Han, JL
2004-09-01
Source PublicationASTRONOMY & ASTROPHYSICS
Volume424Issue:3Pages:793-798
AbstractAn 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 H-beta emission line luminosity, R(light-days)=24.05 (L-H beta/10(42) ergs s(-1))(0.68), 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 R-L-H beta relation are systematically lower than those derived previously with the R-L-5100 Angstrom 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-beta emission line become smaller at greater radio-loudness. If the small H-beta 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 R-L-H beta relation are probably more accurate.
KeywordBlack Hole Physics Galaxies : Active Galaxies : Nuclei Quasars : General Quasars : Emission Lines
DOI10.1051/0004-6361:20035845
Indexed BySCI
Language英语
WOS IDWOS:000224480900011
Citation statistics
Document Type期刊论文
Identifierhttp://ir.bao.ac.cn/handle/114a11/8403
Collection射电天文研究部
Affiliation1.Chinese Acad Sci, Natl Astron Observ, Beijing 100871, Peoples R China
2.Peking Univ, Dept Astron, Beijing 100871, Peoples R China
Recommended Citation
GB/T 7714
Wu, XB,Wang, R,Kong, MZ,et al. Black hole mass estimation using a relation between the BLR size and emission line luminosity of AGN[J]. ASTRONOMY & ASTROPHYSICS,2004,424(3):793-798.
APA Wu, XB,Wang, R,Kong, MZ,Liu, FK,&Han, JL.(2004).Black hole mass estimation using a relation between the BLR size and emission line luminosity of AGN.ASTRONOMY & ASTROPHYSICS,424(3),793-798.
MLA Wu, XB,et al."Black hole mass estimation using a relation between the BLR size and emission line luminosity of AGN".ASTRONOMY & ASTROPHYSICS 424.3(2004):793-798.
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