H i terminal velocity curves − lessons learned from N-body/hydrodynamic ‘surrogate’ models of the Milky Way
(2026) In Monthly Notices of the Royal Astronomical Society 547(2).- Abstract
The development of an N-body/hydrodynamic ‘surrogate’ model of the Milky Way (MW) – a model that resembles the MW in several key aspects after many Gyrs of evolution – would be extremely beneficial for Galactic Archaeology. Here, we present four new ‘surrogate’ models, all built with the nexus framework. The simulations contain stars, dark matter and gas. Our most sophisticated model allows gas to evolve thermodynamically, and includes star formation, metal production, and stellar feedback. The other three models in this work have an isothermal gas disc. We examine these new simulations in the context of cold gas observations of the Galaxy. Our focus is the so-called ‘H i terminal velocity curve’ – a heliocentric measurement of the... (More)
The development of an N-body/hydrodynamic ‘surrogate’ model of the Milky Way (MW) – a model that resembles the MW in several key aspects after many Gyrs of evolution – would be extremely beneficial for Galactic Archaeology. Here, we present four new ‘surrogate’ models, all built with the nexus framework. The simulations contain stars, dark matter and gas. Our most sophisticated model allows gas to evolve thermodynamically, and includes star formation, metal production, and stellar feedback. The other three models in this work have an isothermal gas disc. We examine these new simulations in the context of cold gas observations of the Galaxy. Our focus is the so-called ‘H i terminal velocity curve’ – a heliocentric measurement of the maximum V los as a function of Galactic longitude l , which dates back to the early days of radio astronomy. It is a powerful approach to indirectly estimating the gas dynamics because it does not require knowledge about the distance to individual gas clouds, which is difficult to estimate. A comparison of the terminal velocities and recovered rotation curve values in the simulations against observations suggests that our models are in need of further refinement. The gravitational torques associated with our synthetic bars are too strong, driving excessive streaming motion in the inner gas disc. This causes the simulated terminal velocity curves in the Galactic Quadrant I and IV to deviate substantially from each other, unlike what is seen in observed H i terminal velocities of the MW. We suggest possible ways forward for future models.
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- author
- Davis, Hillary ; Tepper-García, Thor ; McClure-Griffiths, Naomi ; Bland-Hawthorn, Joss LU and Agertz, Oscar LU
- organization
- publishing date
- 2026-04-01
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- galaxies: bar, galaxies: kinematics and dynamics, Galaxy: structure, hydrodynamics, ISM: kinematics and dynamics, software: simulations
- in
- Monthly Notices of the Royal Astronomical Society
- volume
- 547
- issue
- 2
- article number
- staf2166
- publisher
- Oxford University Press
- external identifiers
-
- scopus:105032102119
- ISSN
- 0035-8711
- DOI
- 10.1093/mnras/staf2166
- language
- English
- LU publication?
- yes
- additional info
- Publisher Copyright: © The Author(s) 2025. Published by Oxford University Press on behalf of Royal Astronomical Society.
- id
- 6e19cbbe-c22d-43c9-93ce-fd290942440a
- date added to LUP
- 2026-05-05 13:46:12
- date last changed
- 2026-05-05 13:47:06
@article{6e19cbbe-c22d-43c9-93ce-fd290942440a,
abstract = {{<p>The development of an N-body/hydrodynamic ‘surrogate’ model of the Milky Way (MW) – a model that resembles the MW in several key aspects after many Gyrs of evolution – would be extremely beneficial for Galactic Archaeology. Here, we present four new ‘surrogate’ models, all built with the nexus framework. The simulations contain stars, dark matter and gas. Our most sophisticated model allows gas to evolve thermodynamically, and includes star formation, metal production, and stellar feedback. The other three models in this work have an isothermal gas disc. We examine these new simulations in the context of cold gas observations of the Galaxy. Our focus is the so-called ‘H i terminal velocity curve’ – a heliocentric measurement of the maximum V <sub>los</sub> as a function of Galactic longitude l , which dates back to the early days of radio astronomy. It is a powerful approach to indirectly estimating the gas dynamics because it does not require knowledge about the distance to individual gas clouds, which is difficult to estimate. A comparison of the terminal velocities and recovered rotation curve values in the simulations against observations suggests that our models are in need of further refinement. The gravitational torques associated with our synthetic bars are too strong, driving excessive streaming motion in the inner gas disc. This causes the simulated terminal velocity curves in the Galactic Quadrant I and IV to deviate substantially from each other, unlike what is seen in observed H i terminal velocities of the MW. We suggest possible ways forward for future models.</p>}},
author = {{Davis, Hillary and Tepper-García, Thor and McClure-Griffiths, Naomi and Bland-Hawthorn, Joss and Agertz, Oscar}},
issn = {{0035-8711}},
keywords = {{galaxies: bar; galaxies: kinematics and dynamics; Galaxy: structure; hydrodynamics; ISM: kinematics and dynamics; software: simulations}},
language = {{eng}},
month = {{04}},
number = {{2}},
publisher = {{Oxford University Press}},
series = {{Monthly Notices of the Royal Astronomical Society}},
title = {{H i terminal velocity curves − lessons learned from N-body/hydrodynamic ‘surrogate’ models of the Milky Way}},
url = {{http://dx.doi.org/10.1093/mnras/staf2166}},
doi = {{10.1093/mnras/staf2166}},
volume = {{547}},
year = {{2026}},
}