An important quantity for studying the growth of supermassive black holes is their mass. There are many techniques available to measure or estimate the mass of a black hole and many of them rely on measuring the motions of gas close to the black hole, in the “broad line region”, the light emitted from that gas. But gas clouds in the vicinity of the black hole can absorb/block emission from this gas, systematically affecting our estimates of black hole masses. In “BASS XXIX: The near-infrared view of the BLR: the effects of obscuration in BLR characterisation” (Ricci+) we use near infrared observations to study how estimated black hole masses are affected by the amount of obscuring gas and dust towards the black hole. We find that the measured velocities of the gas are relatively unaffected by the dust/gas extinction, but luminosities can be suppressed, resulting in systematic underestimates of the black hole mass.
The paper has been accepted for publication in the Astrophysical Journal and will appear in the BAT AGN Spectroscopic Survey (BASS) Data Release 2 special issue.