Low-Mass Active Galactic Nuclei with Rapid X-Ray Variability

Understand

We present a detailed study of the optical spectroscopic properties of 12 active galactic nuclei (AGNs) with candidate low-mass black holes (BHs) selected by Kamizasa et al.

• through rapid X-ray variability.
• The high-quality, echellette Magellan spectra reveal broad H$\alpha$ emission in all the sources, allowing us to estimate robust viral BH masses and Eddington ratios for this unique sample.
• We confirm that the sample contains low-mass BHs accreting at high rates: the median $M_{\rm BH} = 1.2\times 10^6M_\odot$ and median $L_{\rm bol}/L_{\rm Edd}=0.44$.