Journal article
WISDOM Project – XIX. Figures of merit for supermassive black hole mass measurements using molecular gas and/or megamaser kinematics
- Abstract:
- The mass (MBH) of a supermassive black hole (SMBH) can be measured using spatially-resolved kinematics of the region where the SMBH dominates gravitationally. The most reliable measurements are those that resolve the smallest physical scales around the SMBHs. We consider here three metrics to compare the physical scales probed by kinematic tracers dominated by rotation: the radius of the innermost detected kinematic tracer Rmin normalised by respectively the SMBH’s Schwarzschild radius (RSchw ≡ 2GMBH/c2, where G is the gravitational constant and c the speed of light), sphere-of-influence (SOI) radius ($R_\mathrm{SOI}\equiv GM_\mathrm{BH}/\sigma _\mathrm{e}^2$, where σe is the stellar velocity dispersion within the galaxy’s effective radius) and equality radius (the radius Req at which the SMBH mass equals the enclosed stellar mass, MBH = M*(Req), where M*(R) is the stellar mass enclosed within the radius R). All metrics lead to analogous simple relations between Rmin and the highest circular velocity probed Vc. Adopting these metrics to compare the SMBH mass measurements using molecular gas kinematics to those using megamaser kinematics, we demonstrate that the best molecular gas measurements resolve material that is physically closer to the SMBHs in terms of RSchw but is slightly farther in terms of RSOI and Req. However, molecular gas observations of nearby galaxies using the most extended configurations of the Atacama Large Millimeter/sub-millimeter Array can resolve the SOI comparably well and thus enable SMBH mass measurements as precise as the best megamaser measurements.
- Publication status:
- Published
- Peer review status:
- Peer reviewed
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(Preview, Version of record, pdf, 1.6MB, Terms of use)
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- Publisher copy:
- 10.1093/mnras/stae1106
Authors
- Publisher:
- Oxford University Press
- Journal:
- Monthly Notices of the Royal Astronomical Society More from this journal
- Volume:
- 530
- Issue:
- 3
- Pages:
- 3240–3251
- Publication date:
- 2024-04-24
- Acceptance date:
- 2024-04-22
- DOI:
- EISSN:
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1365-2966
- ISSN:
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0035-8711
- Language:
-
English
- Keywords:
- Pubs id:
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1992447
- Local pid:
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pubs:1992447
- Deposit date:
-
2024-05-06
Terms of use
- Copyright holder:
- Zhang et al
- Copyright date:
- 2024
- Rights statement:
- © 2024 The Author(s). Published by Oxford University Press on behalf of Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
- Licence:
- CC Attribution (CC BY)
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