A uniformly selected sample of low-mass black holes in seyfert1 galaxies

Xiao Bo Dong, Luis C. Ho, Weimin Yuan, Ting Gui Wang, Xiaohui Fan, Hongyan Zhou, Ning Jiang

Research output: Contribution to journalArticle

70 Scopus citations

Abstract

We have conducted a systematic search of low-mass black holes (BHs) in active galactic nuclei (AGNs) with broad Hα emission lines, aiming at building a homogeneous sample that is more complete than previous ones for fainter, less highly accreting sources. For this purpose, we developed a set of elaborate, automated selection procedures and applied it uniformly to the Fourth Data Release of the Sloan Digital Sky Survey. Special attention is given to AGN-galaxy spectral decomposition and emission-line deblending. We define a sample of 309 type 1 AGNs with BH masses in the range 8 × 104-2 × 106 M (with a median of 1.2 × 106 M ), using the virial mass estimator based on the broad Hα line. About half of our sample of low-mass BHs differs from that of Greene & Ho, with 61 of them discovered here for the first time. Our new sample picks up more AGNs with low accretion rates: the Eddington ratios of the present sample range from ≲ 0.01 to 1, with 30% below 0.1. This suggests that a significant fraction of low-mass BHs in the local universe are accreting at low rates. The host galaxies of the low-mass BHs have luminosities similar to those of L* field galaxies, optical colors of Sbc spirals, and stellar spectral features consistent with a continuous star formation history with a mean stellar age of less than 1Gyr.

Original languageEnglish (US)
Article number167
JournalAstrophysical Journal
Volume755
Issue number2
DOIs
StatePublished - Aug 20 2012

Keywords

  • galaxies: Seyfert
  • galaxies: active
  • galaxies: nuclei

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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