Dark matter fraction derived from the M31 rotation curve

Mass estimates of a spiral galaxy derived from its rotation curve must account for the galaxy’s past accretion history. There are several lines of evidence indicating that M31 experienced a major merger 2 to 3 Gyr ago. In this work, we generated a dynamical model of M31 as a merger remnant that reproduces most of its properties, including from the central bar to the outskirts. The model accounts for M31’s past major merger and reproduces the details of its rotation curve, including its 14 kpc bump and the observed increase of velocity beyond 25 kpc. We find non-equilibrium and oscillatory motions in the gas of the merger-remnant outskirts caused by material in a tidal tail returning to the merger remnant. A total dynamical M31 mass of 4.5 × 10 11 M ⊙ within 137 kpc was obtained after scaling it to the observed HI rotation curve. Within this radial distance, we find that 68% of the total dynamical mass is dark.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2025-02-01
DOI
https://doi.org/10.1051/0004-6361/202452753
Citations
3
Primary Topic
Cosmology and Gravitation Theories
Type
article
Field-Weighted Citation Impact
3.46

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article

Dark matter fraction derived from the M31 rotation curve

G. A. Mamon, L. Chemin, F. Hammer, P. Amram et al.
3 citations
Astronomy and Astrophysics
Cosmology and Gravitation Theories
3.46
article

Dark matter fraction derived from the M31 rotation curve

G. A. Mamon, L. Chemin, F. Hammer, P. Amram, J. L. Wang, H. F. Wang, Yanbin Yang, I. Akib, Yuyang Jiao
article en
3 citations

Abstract

Mass estimates of a spiral galaxy derived from its rotation curve must account for the galaxy’s past accretion history. There are several lines of evidence indicating that M31 experienced a major merger 2 to 3 Gyr ago. In this work, we generated a dynamical model of M31 as a merger remnant that reproduces most of its properties, including from the central bar to the outskirts. The model accounts for M31’s past major merger and reproduces the details of its rotation curve, including its 14 kpc bump and the observed increase of velocity beyond 25 kpc. We find non-equilibrium and oscillatory motions in the gas of the merger-remnant outskirts caused by material in a tidal tail returning to the merger remnant. A total dynamical M31 mass of 4.5 × 10 11 M ⊙ within 137 kpc was obtained after scaling it to the observed HI rotation curve. Within this radial distance, we find that 68% of the total dynamical mass is dark.

Astronomy and AstrophysicsVol. 694
Centre National de la Recherche Scientifique (FR), Universidad Andrés Bello (CL), Université Paris Cité (FR), Aix-Marseille Université (FR), Université Paris Sciences et Lettres (FR), Institut d'Astrophysique de Paris (FR), Sorbonne Université (FR), Sorbonne Paris Cité (FR), Osservatorio Astronomico di Padova (IT)
China Scholarship Council, Centre National de la Recherche Scientifique, Institute of High Energy Physics, National Astronomical Observatories, Chinese Academy of Sciences
Openalex Percentile: Top 9%
Cosmology and Gravitation Theories
3.46
DOIOpen Access PDFOpenAlex
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Dark matter fraction derived from the M31 rotation curve — G. A. Mamon, L. Chemin, et al. · Astronomy and Astrophysics (2025) | TGRS Research Map | TGRS