The Effect of Spatial Gradients in Stellar Mass-to-Light Ratio on Black Hole Mass Measurements

Abstract

We have tested the effect of spatial gradients in stellar mass-to-light ratio (Y) on measurements of black hole masses (MBH) derived from stellar orbit superposition models. Such models construct a static gravitational potential for a galaxy and its central black hole, but typically assume spatially uniform Y. We have modeled three giant elliptical galaxies with gradients alpha = d(log Y)/d(log r) from -0.2 to +0.1. Color and line strength gradients suggest mildly negative alpha in these galaxies. Introducing a negative (positive) gradient in Y increases (decreases) the enclosed stellar mass near the center of the galaxy and leads to systematically smaller (larger) MBH measurements. For models with alpha = -0.2, the best-fit values of MBH are 28%, 27%, and 17% lower than the constant-Y case, in NGC 3842, NGC 6086, and NGC 7768, respectively. For alpha = +0.1, MBH are 14%, 22%, and 17% higher than the constant-Y case for the three respective galaxies. For NGC 3842 and NGC 6086, this bias is comparable to the statistical errors from individual modeling trials. At larger radii, negative (positive) gradients in Y cause the total stellar mass to decrease (increase) and the dark matter fraction within one effective radius to increase (decrease).

6 pages, 4 figures, 1 table. To appear in ApJL

References in corpus (12)

• Revisiting the Scaling Relations of Black Hole Masses and Host Galaxy Properties
• The Stellar Initial Mass Function in Early-Type Galaxies From Absorption Line Spectroscopy. II. Results
• Population Synthesis in the Blue IV: Accurate Model Predictions for Lick Indices and UBV Colors in Single Stellar Populations
• The Black Hole Mass, Stellar M/L, and Dark Halo in M87
• The Density Profiles of Massive, Relaxed Galaxy Clusters. II. Separating Luminous and Dark Matter in Cluster Cores
• Separating baryons and dark matter in cluster cores: a full 2-D lensing and dynamic analysis of Abell 383 and MS2137-23
• Measuring Ages and Elemental Abundances from Unresolved Stellar Populations: Fe, Mg, C, N, and Ca
• The mass-metallicity gradient relation of early-type galaxies
• The stellar mass structure of massive galaxies from z=0 to z=2.5; surface density profiles and half-mass radii
• The Baryon Fractions and Mass-to-Light Ratios of Early-Type Galaxies
• Radial kinematics of brightest cluster galaxies
• The supermassive black hole in NGC4486a detected with SINFONI at the VLT

Cited by in corpus (26)

• The M87 Black Hole Mass from Gas-dynamical Models of Space Telescope Imaging Spectrograph Observations
• Improved Dynamical Constraints on the Mass of the central Black Hole in NGC 404
• A 5x10^9 Solar Mass Black Hole in NGC 1277 from Adaptive Optics Spectroscopy
• The Black Hole Mass of NGC 4151. II. Stellar Dynamical Measurement from Near-Infrared Integral Field Spectroscopy
• The Black Hole - Bulge Mass Relation in Megamaser Host Galaxies
• Measurement of the Black Hole Mass in NGC 1332 from ALMA Observations at 0.044 Arcsecond Resolution
• MRK 1216 & NGC 1277 - An orbit-based dynamical analysis of compact, high velocity dispersion galaxies
• A new implementation of the Schwarzschild method for constructing observationally-driven dynamical models of galaxies of all morphological types
• Six new supermassive black hole mass determinations from adaptive-optics assisted SINFONI observations
• A Precision Measurement of the Mass of the Black Hole in NGC 3258 from High-Resolution ALMA Observations of its Circumnuclear Disk
• The MBHBM* Project -- I: Measurement of the Central Black Hole Mass in Dwarf Galaxy NGC 3504 Using Molecular Gas Kinematics
• Toward Precision Black Hole Masses with ALMA: NGC 1332 as a Case Study in Molecular Disk Dynamics
• A Black Hole Mass Determination for the Compact Galaxy Mrk 1216
• On the Offset of Barred Galaxies From the Black Hole $M_{BH}$-$\sigma$ Relationship
• Black hole mass measurement using ALMA observations of [CI] and CO emissions in the Seyfert 1 galaxy NGC7469
• SDSS-IV MaNGA: Stellar M/L gradients and the M/L-colour relation in galaxies
• A low upper mass limit for the central black hole in the late-type galaxy NGC 4414
• The MBHBM${}^{\star }$ Project -- II. Molecular Gas Kinematics in the Lenticular Galaxy NGC 3593 Reveal a Supermassive Black Hole
• Effect of the initial mass function on the dynamical SMBH mass estimate in the nucleated early-type galaxy FCC 47
• The SLUGGS Survey: The Inner Dark Matter Density Slope of the Massive Elliptical Galaxy NGC 1407
• NGC 307 and the Effects of Dark-Matter Haloes on Measuring Supermassive Black Holes in Disc Galaxies
• The Mass of the Black Hole in NGC 5273 from Stellar Dynamical Modeling
• Comparison of simple mass estimators for slowly rotating elliptical galaxies
• Coevolution (Or Not) of Supermassive Black Holes and Host Galaxies: Black Hole Scaling Relations Are Not Biased by Selection Effects
• The Mitchell Spectrograph: Studying Nearby Galaxies with the VIRUS Prototype
• Cross-checking SMBH mass estimates in NGC 6958 -- I: Stellar dynamics from adaptive optics-assisted MUSE observations