Revisiting the Stellar-Dynamical Mass of the Central Black Hole in NGC 3227
Abstract
We present a new stellar-dynamical mass for the supermassive black hole in the nearby Seyfert galaxy NGC 3227. We determined the line-of-sight velocity distributions of stars in the nuclear region of NGC 3227 using archival spatially-resolved K-band spectra obtained with NIFS at Gemini Observatory. The surface brightness profile of the galaxy is described by four components, measured from a WFC3 F547M image from the Hubble Space Telescope. We constructed dynamical models using the Schwarzschild orbit-superposition method implemented in the open-source code FORSTAND. We find a best-fit black hole mass of MBH=(1.2±0.5) × 107 M⊙. This mass is consistent with a previous mass from R. I. Davies et al. based on stellar dynamics using orbit-based modeling, but our results make use of higher signal-to-noise data from which the higher-order moments of the stellar LOSVDs are constrained, thus providing a more precise MBH. Our result is also consistent with the MBH constraint from velocity-resolved reverberation mapping reported by M. C. Bentz et al.. And while our best-fit mass is slightly smaller than the mass constraint from gas-dynamical modeling reported by E. K. S. Hicks & M. A. Malkan (after scaling to the same adopted distance), they are within 2σ of each other. Direct comparisons of black hole masses from different techniques are rare but crucial to ensure all black hole masses are on the same scale, and to identify and minimize the uncertainties and possible sources of bias associated with each technique.
Related
- A stellar dynamical mass measurement of an inactive black hole at redshift 2
- Satellite stellar-to-halo mass relations in primordial black hole universes
- Disentangling the assembly of the central and diffuse stellar components in galaxy clusters through dynamical friction and tidal stripping
- Disentangling the assembly of the central and diffuse stellar components in galaxy clusters through dynamical friction and tidal stripping
- Dynamical Mass Demography of Single S-type Planets Shaped by Stellar Companions
BibTeX
@misc{das2026revisiting,
title = {{Revisiting the Stellar-Dynamical Mass of the Central Black Hole in NGC 3227}},
author = {Nabanita Das and Misty C. Bentz and Eugene Vasiliev and Monica Valluri and Christopher A. Onken},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.05547},
eprint = {2611.05547},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.05547},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Revisiting the Stellar-Dynamical Mass of the Central Black Hole in NGC 3227
AU - Nabanita Das
AU - Misty C. Bentz
AU - Eugene Vasiliev
AU - Monica Valluri
AU - Christopher A. Onken
PY - 2026
DA - 2026/11/03
PB - arXiv
DO - 10.48550/arxiv.2611.05547
UR - https://arxiv.org/abs/2611.05547
AB - We present a new stellar-dynamical mass for the supermassive black hole in the nearby Seyfert galaxy NGC 3227. We determined the line-of-sight velocity distributions of stars in the nuclear region of NGC 3227 using archival spatially-resolved K-band spectra obtained with NIFS at Gemini Observatory. The surface brightness profile of the galaxy is described by four components, measured from a WFC3 F547M image from the Hubble Space Telescope. We constructed dynamical models using the Schwarzschild orbit-superposition method implemented in the open-source code FORSTAND. We find a best-fit black hole mass of M_BH=(1.2±0.5) × 10^7 M_⊙. This mass is consistent with a previous mass from R. I. Davies et al. based on stellar dynamics using orbit-based modeling, but our results make use of higher signal-to-noise data from which the higher-order moments of the stellar LOSVDs are constrained, thus providing a more precise M_BH. Our result is also consistent with the M_BH constraint from velocity-resolved reverberation mapping reported by M. C. Bentz et al.. And while our best-fit mass is slightly smaller than the mass constraint from gas-dynamical modeling reported by E. K. S. Hicks & M. A. Malkan (after scaling to the same adopted distance), they are within 2σ of each other. Direct comparisons of black hole masses from different techniques are rare but crucial to ensure all black hole masses are on the same scale, and to identify and minimize the uncertainties and possible sources of bias associated with each technique.
ER -