Intermediate-mass black holes in galactic nuclei

Abstract

We present the first homogeneous sample of intermediate-mass black hole candidates in active galactic nuclei. Starting with broad-line active nuclei from the Sloan Digital Sky Survey, we use the linewidth-luminosity-mass scaling relation to select a sample of 19 galaxies in the mass range $M_{\mathrm{BH}} \approx 8 \times 10^4 - 10^6\,\ensuremath{M_{\odot}}$. In contrast to the local active galaxy population, the host galaxies are ∼1 mag fainter than M* and thus are probably late-type systems. The active nuclei are also faint, with $M_g \approx -15$ to −18 mag, while the bolometric luminosities are close to the Eddington limit. The spectral properties of the sample are compared to the related class of objects known as narrow-line Seyfert 1 galaxies. We discuss the importance of our sample as observational analogues of primordial black holes, contributors to the integrated signal for future gravitational wave experiments, and as a valuable tool in the calibration of the MBM–σ∗ relation.To search for other articles by the author(s) go to: http://adsabs.harvard.edu/abstract_service.html