The SDSS-V Black Hole Mapper Reverberation Mapping Project: Multiline Dynamical Modeling of a Highly Variable Active Galactic Nucleus with Decade-long Light Curves

We present dynamical modeling of the broad-line region (BLR) of the highly variable active galactic nucleus (AGN) SDSS J141041.25+531849.0 ( z = 0.359) using photometric and spectroscopic monitoring data from the Sloan Digital Sky Survey (SDSS) Reverberation Mapping project and the current fifth-generation SDSS Black Hole Mapper program, spanning from early 2013 to early 2023. We model the geometry and kinematics of the BLR in the H β , H α , and Mg ii emission lines for three different time periods to measure the potential change of structure within the BLR across time and line species. We find a moderately face-on ( i full - state = 29 . 68 − 3.62 + 4.74 deg ) thick-disk ( θ opn , full − state = 42 . 04 − 3.96 + 4.32 deg ) geometry for most BLRs, with a joint estimate for the mass of the supermassive black hole for each of three time periods, yielding log 10 ( M BH / M ⊙ ) = 8.1 0 − 0.03 + 0.03 when using the full data set. The inferred individual virial factor f ∼ 1.6 is moderately smaller than the average factor for a local sample of dynamically modeled AGNs. There is strong evidence for nonvirial motion, with over 70% of clouds on inflowing/outflowing orbits. We analyze the change in model parameters across emission lines, finding the radii of BLRs for the emission lines are consistent with the following relative sizes R H β ≲ R MgII ≲ R H α . Comparing results across time, we find R low-state ≲ R high-state , with the change in BLR size for H β being more significant than for the other two lines. The data also reveal complex, time-evolving, and potentially transient dynamics of the BLR gas over a decade-long timescale, encouraging for future dynamical modeling of fine-scale BLR kinematics.