A novel black hole mass scaling using coronal lines in active galaxies

Swayamtrupta Panda and Alberto Rodrı́guez-Ardila

Using bona-fide black hole (BH) mass estimates from reverberation mapping and the line ratio [SiVI] 1.963µm/Brγ_broad as tracer of the Active Galactic Nuclei (AGN) ionizing continuum, we find a novel BH-mass scaling relation of the form log(M_BH) = (6.40 ± 0.17) − (1.99 ± 0.37)× log ([SiVI]/Brγ_broad), over the BH mass interval, 10⁶-10⁸ [M_☉]. The analyzed sample consists of 21 Type-1 AGNs with the overall dispersion in our scaling relation at 0.47 dex, one that emulates the well-established M-σ relation, which shows a dispersion ∼0.44 dex. The new scaling offers an economically and physically motivated alternative for BH mass estimate using single epoch spectra, avoiding large telescope time (reverberation mapping) or absolute flux calibration (the continuum luminosity method). With the advent of deep infrared surveys in the near future, we aim to reduce the scatter in our novel relation by supplementing with more sources.

Proceedings of the Polish Astronomical Society, vol. 12, 79-81 (2022)

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