Revealing the intermediate-mass black hole at the heart of the dwarf galaxy NGC404 with sub-parsec resolution ALMA observations
Journal article, 2020
We estimate the mass of the intermediate-mass black hole at the heart of the dwarf elliptical galaxy NGC 404 using Atacama Large Millimetre/submillimetre Array (ALMA) observations of the molecular interstellar medium at an unprecedented linear resolution of approximate to 0.5 pc, in combination with existing stellar kinematic information. These ALMA observations reveal a central disc/torus of molecular gas clearly rotating around the black hole. This disc is surrounded by a morphologically and kinematically complex flocculent distribution of molecular clouds, that we resolve in detail. Continuum emission is detected from the central parts of NGC 404, likely arising from the Rayleigh-Jeans tail of emission from dust around the nucleus, and potentially from dusty massive star-forming clumps at discrete locations in the disc. Several dynamical measurements of the black hole mass in this system have been made in the past, but they do not agree. We show here that both the observed molecular gas and stellar kinematics independently require a approximate to 5 x 10(5) M-circle dot black hole once we include the contribution of the molecular gas to the potential. Our best estimate comes from the high-resolution molecular gas kinematics, suggesting the black hole mass of this system is 5.5(-3.8)(+4.1) x 10(5) M-circle dot (at the 99 per cent confidence level), in good agreement with our revised stellar kinematic measurement and broadly consistent with extrapolations from the black hole mass-velocity dispersion and black hole massbulge mass relations. This highlights the need to accurately determine the mass and distribution of each dynamically important component around intermediate-mass black holes when attempting to estimate their masses.
galaxies: evolution
galaxies: dwarf
galaxies: individual: NGC 404-galaxies
galaxies: elliptical and lenticular, cD
ISM-galaxies: kinematics and dynamics
Author
Timothy A. Davis
Cardiff University
Dieu D. Nguyen
National Institutes of Natural Sciences
Anil C. Seth
University of Utah
Jenny E. Greene
Princeton University
Kristina Nyland
Naval Research Laboratory
Aaron J. Barth
University of California
Martin Bureau
University of Oxford
Yonsei University
Michele Cappellari
University of Oxford
Mark den Brok
Leibniz Institute for Astrophysics Potsdam
Satoru Iguchi
The Graduate University for Advanced Studies (SOKENDAI)
National Institutes of Natural Sciences
Federico Lelli
Cardiff University
Lijie Liu
University of Oxford
Nadine Neumayer
Max Planck Society
North
Cardiff University
Kyoko Onishi
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Marc Sarzi
Armagh Observatory and Planetarium
Mark D. Smith
University of Oxford
Thomas G. Williams
Max Planck Society
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 496 4 4061-4078Subject Categories (SSIF 2011)
Subatomic Physics
Analytical Chemistry
Astronomy, Astrophysics and Cosmology
DOI
10.1093/mnras/staa1567