Measuring the mass of the supermassive black hole of the lenticular galaxy NGC 4546

Abstract

Most galaxies with a well-structured bulge host a supermassive black hole (SMBH) in their centre. Stellar kinematics models applied to adaptive optics (AO) assisted integral field unit observations are well-suited to measure the SMBH mass (MBH) and also the total mass-to-light ratio [(M/L)TOT] and possible anisotropies in the stellar velocity distribution in the central region of galaxies. In this work, we used new AO assisted Near-Infrared Integral Field Spectrometer (NIFS) observations and also photometric data from the Hubble Space Telescope Legacy Archive of the galaxy NGC 4546 in order to determine its SMBH mass. To do this, we applied the Jeans Anisotropic Modelling (JAM) method to fit the average second velocity moment in the line of sight $(\overline{v^2_{\mathrm{ los}}})$ of the stellar structure. In addition, we also obtained (M/L)TOT and the classical anisotropy parameter βz = 1-(σz/σR)2 for this object within a field of view of 200 × 200 pc2. Maps of the stellar radial velocity and of the velocity dispersion were built for this galaxy using the penalized pixel fitting (ppxf) technique. We applied the Multi Gaussian Expansion procedure to fit the stellar brightness distribution. Using JAM, the best-fitting model for $\overline{v^2_{\mathrm{ los}}}$ of the stellar structure was obtained with (M/L)TOT = 4.34 ± 0.07 (Johnson’s R band), MBH = (2.56 ± 0.16) × 108 M⊙ and βz = −0.015 ± 0.03 (3σ confidence level). With these results, we found that NGC 4546 follows the MBH × σ relation. We also measured the central velocity dispersion within a radius of 1 arcsec of this object as σc = 241 ± 2 km s−1.

IFU observations of the inner 200 pc of NGC 4546: gas rotation, non-circular motions, and ionized outflows

“…The gas velocity amplitude is 210 ± 25 km s −1 , twice the velocity amplitude of the stars. In addition, while the stellar velocity field shows a well-behaved rotation pattern and is in agreement with previous works (Ricci et al 2016;Ricci & Steiner 2020), the gas clearly presents deviation of a pure disc rotation pattern. The gas velocity dispersion maps (third column of Figure 2) present values in the range 60-240 km s −1 , smaller than the stellar velocity dispersion at most locations.…”

The MAGPI Survey -- science goals, design, observing strategy, early results and theoretical framework

“…This technique has been used to constrain radial profiles of enclosed dynamical mass, which can be decomposed to further explore the dark-matter and stellar distributions, estimate the initial mass function and potentially black hole mass if the resolution allows (e.g. Cappellari et al, 2012Cappellari et al, , 2013aCappellari et al, ,b, 2015Poci et al, 2017;Bellstedt et al, 2018;Li et al, 2019;Tortora et al, 2019;Ricci & Steiner, 2020). Recent work shows that JAM and Schwarzschild yield consistent black hole mass results (Krajnović et al, 2018;Thater et al, 2019).…”