| 1. |
- Davis, Timothy A., et al.
(författare)
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Revealing the intermediate-mass black hole at the heart of the dwarf galaxy NGC404 with sub-parsec resolution ALMA observations
- 2020
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Ingår i: Monthly Notices of the Royal Astronomical Society. - : Oxford University Press (OUP). - 0035-8711 .- 1365-2966. ; 496:4, s. 4061-4078
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 2. |
- Imanishi, Masatoshi, et al.
(författare)
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ALMA 002 Resolution Observations Reveal HCN-abundance-enhanced Counter-rotating and Outflowing Dense Molecular Gas at the NGC 1068 Nucleus
- 2020
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 1538-4357 .- 0004-637X. ; 902:2
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Tidskriftsartikel (refereegranskat)abstract
- We present ALMA similar to 002 resolution observations of the nucleus of the nearby (similar to 14 Mpc) type 2 active galactic nucleus NGC 1068 at HCN/HCO+/HNCJ = 3-2 lines, as well as at their(13)C isotopologue and vibrationally excited lines, to scrutinize the morphological, dynamical, chemical, and physical properties of dense molecular gas in the putative dusty molecular torus around a mass-accreting supermassive black hole. We confirm almost east-west-oriented dense molecular gas emission both morphologically and dynamically, which we regard as coming from the torus. Bright emission is compact (less than or similar to 3 pc), and low-surface-brightness emission extends out to 5-7 pc. These dense molecular gas properties are not symmetric between the eastern and western torus. The HCNJ = 3-2 emission is stronger than the HCO(+)J = 3-2 emission within the similar to 7 pc torus region, with an estimated dense molecular mass of (0.4-1.0) x 10(6)M. We interpret that HCN abundance is enhanced in the torus. We detect signatures of outflowing dense molecular gas and a vibrationally excited HCNJ = 3-2 line. Finally, we find that in the innermost (less than or similar to 1 pc) part of the torus, the dense molecular line rotation velocity, relative to the systemic velocity, is the opposite of that in the outer (greater than or similar to 2 pc) part, in both the eastern and western torus. We prefer a scenario of counter-rotating dense molecular gas with innermost almost Keplerian rotation and outer slowly rotating (far below Keplerian) components. Our high-spatial-resolution dense molecular line data reveal that torus properties of NGC 1068 are much more complicated than the simple axisymmetrically rotating torus picture in the classical active galactic nucleus unification paradigm.
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