Assessing indirect methods to determine black hole masses using NGC 4151

Accurately determining the black hole mass ($M_\mathrm{BH}$) in active galactic nuclei (AGN) is crucial to constraining their properties and studying evolution. While direct methods yield reliable measurements of $M_\mathrm{BH}$ unobscured type 1 AGN, where dynamics stellar or gas components can be directly observed, only indirect applied vast majority heavily absorbed 2 which represent most AGN population. Since it difficult evaluate accuracy precision these methods, we utilize nearby X-ray bright Seyfert galaxy NGC 4151, whose has been tightly constrained with several independent as a laboratory assess reliability three that have obscured AGN. All three, scaling method, fundamental plane activity, M-$\sigma$ correlation, values consistent those inferred from therefore considered accurate. However, method correlation are precise because substantial scatter BH activity allows for crude estimates. Of four correlations used, one Kormendy Ho yields value dynamical This study suggests best approach estimating systems cannot combination taking into account different ranges applicability.