The Seoul National University AGN Monitoring Project. IV. Hα Reverberation Mapping of Six AGNs and the Hα Size–Luminosity Relation

Author Info

Hojin Cho, Seoul National University
Jong-Hak Woo, Seoul National University
Shu Wang, Seoul National University
Donghoon Son, Seoul National University
Jaejin Shin, Seoul National University
Suvendu Rakshit, Seoul National University
Aaron J. Barth, University of California, Irvine
Vardha N. Bennert, California Polytechnic State University, San Luis ObispoFollow
Elena Gallo, University of Michigan - Ann Arbor
Edmund Hodges-Kluck, University of Michigan - Ann Arbor
Tommaso Treu, University of California, Los Angeles
Hyun-Ji Bae, Seoul National University
Wanjin Cho, Seoul National University
Adi Foord, Stanford University
Jaehyuk Geum, Kyungpook National University
Yashashree Jadhav, Seoul National University
Yiseul Jeon, Seoul National University
Kyle M. Kabasares, University of California, Irvine
Daeun Kang, Seoul National University
Wonseok Kang, National Youth Space Center
Changseok Kim, Seoul National University
Donghwa Kim, Seoul National University
Minjin Kim, Kyungpook National University
Taewoo Kim, National Youth Space Center
Huynh Anh N. Lee, Seoul National University
Matthew A. Malkan, University of California, Los Angeles
Amit Kumar Mandal, Seoul National University
Daeseong Park, Kyungpook National University
Hyun-il Sung, Korea Astronomy and Space Science Institute
Vivian U, University of California, Irvine
Peter R. Williams, University of California, Los Angeles

Recommended Citation

Published in The Astrophysical Journal, Volume 953, Issue 2, August 1, 2023.

The definitive version is available at https://doi.org/10.3847/1538-4357/ace1e5.

Abstract

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 Å, 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, which provides 6 yr photometric and spectroscopic monitoring data, we present our measurements of the Hα lags of high-luminosity AGNs. Combined with the measurements for 42 AGNs from the literature, we derive the size–luminosity relations of the Hα BLR against the broad Hα and 5100 Å 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 Hβ size–luminosity relation. Moreover, we find a linear relation between the 5100 Å 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 scaling relations in the literature are overestimated by up to 0.7 dex at masses lower than 107M_⊙.

Disciplines

Physics

Copyright

© 2023 The Author(s)

Number of Pages

16