Atacama Large Millimeter/submillimeter Array (ALMA) ¹² CO(2–1) Gas Dynamics in NGC 315: A Multimethod Benchmark for Supermassive Black Hole Mass Measurement

@article{nguyen2026atacama,
  title = {{Atacama Large Millimeter/submillimeter Array (ALMA) ¹² CO(2–1) Gas Dynamics in NGC 315: A Multimethod Benchmark for Supermassive Black Hole Mass Measurement}},
  author = {Dieu D. Nguyen and Benjamin D. Boizelle and Hai N. Ngo and Elena Gallo and Tuan N. Le and Sabine Thater and Tien H. T. Ho and Tinh Q. T. Le and Que T. Le and Sam Norcross and Xueyi Li and Huy G. Tong and Nghi K. N. Le and Huy M. B. Tran},
  journal = {The Astrophysical Journal},
  year = {2026},
  month = oct,
  doi = {10.3847/1538-4357/aea151},
  url = {https://iopscience.iop.org/article/10.3847/1538-4357/aea151},
  note = {CC BY 4.0},
}

TY  - JOUR
TI  - Atacama Large Millimeter/submillimeter Array (ALMA) ¹² CO(2–1) Gas Dynamics in NGC 315: A Multimethod Benchmark for Supermassive Black Hole Mass Measurement
AU  - Dieu D. Nguyen
AU  - Benjamin D. Boizelle
AU  - Hai N. Ngo
AU  - Elena Gallo
AU  - Tuan N. Le
AU  - Sabine Thater
AU  - Tien H. T. Ho
AU  - Tinh Q. T. Le
AU  - Que T. Le
AU  - Sam Norcross
AU  - Xueyi Li
AU  - Huy G. Tong
AU  - Nghi K. N. Le
AU  - Huy M. B. Tran
PY  - 2026
DA  - 2026/10/08
JO  - The Astrophysical Journal
DO  - 10.3847/1538-4357/aea151
UR  - https://iopscience.iop.org/article/10.3847/1538-4357/aea151
AB  - We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 7 ¹² CO(2−1) observations of the circumnuclear disk in NGC 315 at an angular resolution of 0 . ″ 230 × 0 . ″ 175 , improving on past measurements and resolving the sphere of influence (SOI) of the supermassive black hole (SMBH), whose mass has been estimated previously as M BH = 2.0 8 − 0.15 + 0.33 × 1 0 9 M ⊙ . The high spatial resolution and sensitivity enable robust full-cube forward modeling of the molecular gas kinematics and a direct comparison of multiple independent gas-based dynamical modeling techniques. We apply standard Bayesian codes using both Markov chain Monte Carlo (MCMC) and nested sampling approaches, as well as a frequentist code to the same data set, exploring systematic uncertainties associated with the stellar mass distribution, gas surface-brightness parameterization, and disk geometry. All methods yield consistent black hole masses, indicating that the inferred M BH is not strongly method-dependent. Combining the ensemble of independent molecular-gas-based models, we derive an ensemble median black hole mass of M BH / 1 0 9 M ⊙ = 2.0 2 − 0.05 + 0.04 (stat) − 0.04 + 0.05 (sys), where the comparable contributions to the full error budget arise from modeling systematics rather than formal fitting uncertainties. Our M BH is consistent with the empirical M BH – σ ⋆ and M BH – L bulge scaling relations, and lies 32% below an independent stellar-dynamical measurement—a discrepancy we discuss in the context of systematic differences between gas- and stellar-based methods. NGC 315 serves as a benchmark for quantifying molecular gas-dynamical M BH systematic uncertainties and for future cross-comparisons of gaseous and stellar dynamical approaches.
SN  - 0004-637X
SN  - 1538-4357
ER  -