The Baryonic Faber-Jackson Relation and Fundamental Plane of Galaxy Groups, Elliptical Galaxies, and Dwarf Galaxies

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Main Authors: Tian, Yong, Lelli, Federico, Pawlowski, Marcel S., McGaugh, Stacy, Duann, Yi, Chae, Kyu-Hyun, Di Teodoro, Enrico, Haubner, Konstantin, Kuo, Meng Hua, Ko, Chung-Ming
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Published: 2026
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author Tian, Yong
Lelli, Federico
Pawlowski, Marcel S.
McGaugh, Stacy
Duann, Yi
Chae, Kyu-Hyun
Di Teodoro, Enrico
Haubner, Konstantin
Kuo, Meng Hua
Ko, Chung-Ming
author_facet Tian, Yong
Lelli, Federico
Pawlowski, Marcel S.
McGaugh, Stacy
Duann, Yi
Chae, Kyu-Hyun
Di Teodoro, Enrico
Haubner, Konstantin
Kuo, Meng Hua
Ko, Chung-Ming
contents The baryonic Faber-Jackson relation (BFJR) links the baryonic mass of pressure-supported systems to their mean velocity dispersion. For elliptical galaxies, the BFJR is thought to be a projection of the fundamental plane (FP), which includes the stellar half-mass radius as a third variable. We study the BFJR and FP across eight orders of magnitude in baryonic mass, encompassing galaxy groups, ellipticals, dwarf ellipticals, and dwarf spheroidals. We compile and homogenize data for 1400 pressure-supported systems and measure their mean internal baryonic acceleration $\langle g_\mathrm{bar}\rangle$. We find that the properties of the BFJR and FP systematically depend on the internal acceleration of the sampled systems, with a transition around the acceleration scale $a_0\simeq 1.2\times10^{10}$ m s$^{-2}$. For low-acceleration systems with $\langle g_\mathrm{bar}\rangle < 0.6\,a_0$ (dwarf galaxies and galaxy groups), the BFJR relation takes the form $\log_{10}(M_\mathrm{bar}/M_{\odot}) = (4.19 \pm 0.10) \log_{10}(σ_{\rm los}/\rm{km s}^{-1}) + (2.55^{+0.16}_{-0.16})$ with an orthogonal intrinsic scatter of $0.11 \pm 0.01$ dex. The FP expected from the Newtonian virial theorem is followed by high-acceleration systems (massive ellipticals with $\langle g_\mathrm{bar}\rangle \gtrsim 6 \,a_0$), whereas low-acceleration systems deviate from the FP at both low masses (dwarf galaxies) and high masses (galaxy groups). Our results generally agree with the expectations of MOND: high-acceleration systems follow the Newtonian virial theorem in which a radial variable explicitly appears (the FP), while low-acceleration systems follow the MOND virial theorem in which the radial dependence disappears (the BFJR). On average, the MOND external field effect seems to play a secondary role in dwarf galaxies in galaxy groups and clusters.
format Preprint
id arxiv_https___arxiv_org_abs_2605_26965
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Baryonic Faber-Jackson Relation and Fundamental Plane of Galaxy Groups, Elliptical Galaxies, and Dwarf Galaxies
Tian, Yong
Lelli, Federico
Pawlowski, Marcel S.
McGaugh, Stacy
Duann, Yi
Chae, Kyu-Hyun
Di Teodoro, Enrico
Haubner, Konstantin
Kuo, Meng Hua
Ko, Chung-Ming
Astrophysics of Galaxies
The baryonic Faber-Jackson relation (BFJR) links the baryonic mass of pressure-supported systems to their mean velocity dispersion. For elliptical galaxies, the BFJR is thought to be a projection of the fundamental plane (FP), which includes the stellar half-mass radius as a third variable. We study the BFJR and FP across eight orders of magnitude in baryonic mass, encompassing galaxy groups, ellipticals, dwarf ellipticals, and dwarf spheroidals. We compile and homogenize data for 1400 pressure-supported systems and measure their mean internal baryonic acceleration $\langle g_\mathrm{bar}\rangle$. We find that the properties of the BFJR and FP systematically depend on the internal acceleration of the sampled systems, with a transition around the acceleration scale $a_0\simeq 1.2\times10^{10}$ m s$^{-2}$. For low-acceleration systems with $\langle g_\mathrm{bar}\rangle < 0.6\,a_0$ (dwarf galaxies and galaxy groups), the BFJR relation takes the form $\log_{10}(M_\mathrm{bar}/M_{\odot}) = (4.19 \pm 0.10) \log_{10}(σ_{\rm los}/\rm{km s}^{-1}) + (2.55^{+0.16}_{-0.16})$ with an orthogonal intrinsic scatter of $0.11 \pm 0.01$ dex. The FP expected from the Newtonian virial theorem is followed by high-acceleration systems (massive ellipticals with $\langle g_\mathrm{bar}\rangle \gtrsim 6 \,a_0$), whereas low-acceleration systems deviate from the FP at both low masses (dwarf galaxies) and high masses (galaxy groups). Our results generally agree with the expectations of MOND: high-acceleration systems follow the Newtonian virial theorem in which a radial variable explicitly appears (the FP), while low-acceleration systems follow the MOND virial theorem in which the radial dependence disappears (the BFJR). On average, the MOND external field effect seems to play a secondary role in dwarf galaxies in galaxy groups and clusters.
title The Baryonic Faber-Jackson Relation and Fundamental Plane of Galaxy Groups, Elliptical Galaxies, and Dwarf Galaxies
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2605.26965