J/A+A/707/A137 MaNGA and ATLAS3D ETGs kinematic data (Zhong+, 2026)
Unifying the dynamical classification of early-type galaxies:
Kinematic deficits in IllustrisTNG versus observations
Zhong W., Du M., Lu S., Jin Y., Zhu K.
<Astron. Astrophys. 707, A137 (2026)>
=2026A&A...707A.137Z 2026A&A...707A.137Z (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Morphology ; Optical
Keywords: galaxies: fundamental parameters - galaxies: interactions -
galaxies: kinematics and dynamics - galaxies: statistics -
galaxies: stellar content - galaxies: structure
Abstract:
This study aims to make a comparative analysis of galaxy kinematics
using IllustrisTNG simulations and integral-field spectroscopy (IFS)
observations.
We identify 2342 early-type galaxies (ETGs) from the TNG100 simulation
and 236 ETGs from the TNG50 simulation to compare with those from
MaNGA and ATLAS3D surveys. For these systems, we measure key
kinematic parameters widely employed in both observational and
simulation-based studies, including the intrinsic spin parameter
λR,intr (it indicates that the λR parameter is
measured when the galaxy is viewed edge-on), the cylindrical
rotational energy fraction κrot, and structural mass ratios
such as the spheroid mass fraction fspheroid and the stellar halo
mass fraction fhalo.
This study performs a comparative kinematic analysis of early-type
galaxies using IllustrisTNG simulations and IFS data from MaNGA
and ATLAS3D . We demonstrate that standard classifiers --- the
λR(Re)=0.31 SQRT(epsilon) relation and k5{bar} coefficient
(the higher-order term of the Fourier decomposition of velocity
fields) --- fail to align with kinematic bimodality. Revised
thresholds are proposed: the spin λR,intr∼0.4, the ratio of
rotation energy κrot∼0.5, and the mass fraction of a spheroid
component fspheroid∼0.6. It provides a universal threshold that
classifies all kinds of galaxies into rotation-dominated (fast
rotators) and random motion-dominated (slow rotators) cases. Scaling
relations derived from TNG enable estimation of κrot and
fspheroid from observations. TNG simulations exhibit a bimodality
deficit, characterized by a lack of fast rotators and suppressed
λR,intr, attributable to excess galaxies with intermediate
rotation and high spheroid/stellar halo mass. A novel method for
estimating stellar halo mass fractions from IFS kinematics is
introduced, though significant uncertainties persist.
Description:
Table with main properties of 933 MaNGA galaxies and 193 ATLAS^3D
galaxies used in the paper. Unlike the data shown in Table 1 of the
paper, columns 8 to 12 present additional kinematic data as well as
new kinematic classification results, respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
atlas.dat 79 193 ATLAS3D kinematic data
manga.dat 79 933 MaNGA kinematic data (table 1)
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Byte-by-byte Description of file: atlas.dat manga.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name ID associated with a specific observation
for a unique galaxy
13- 18 F6.3 deg Inc Inclination of galaxy
20- 24 F5.3 --- Ell(Re) Ellipticity measured within Re
26- 30 F5.3 --- LR(Re) Stellar spin parameter LambdaR,intr(Re)
calculated within Re (1)
32- 36 F5.3 --- LRintr(Re) ?=- Intrinsic stellar spin parameter
LambdaR,intr(Re) calculated within Re
38- 43 F6.3 --- kapparot(all) ?=- Significance of cylindrical rotation
kapparot(all) calculated from all
stars
45- 50 F6.3 --- fspheroid(all) ?=- Spheroid mass fraction
fspheroid(all) calculated from all
stars
52- 57 F6.3 --- fhalo(all) ?=- Stellar halo mass fraction
fhalo(all) calculated from all stars
59- 63 F5.3 --- kapparot(Re) ?=- Significance of cylindrical rotation
kapparot(Re) calculated within Re
65- 69 F5.3 --- fspheroid(Re) ?=- Spheroid mass fraction
fspheroid(Re) calculated within Re
71- 76 F6.3 --- fhalo(Re) ?=- Stellar halo mass fraction
fhalo(Re) calculated within Re
78- 79 A2 --- Class New kinematic classification (2)
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Note (1): We approximate the intrinsic spin parameter Lambda_R,intr(Re) based on
Equations (5) and (6) in this paper.
For ATLAS^3D, we leverage the empirical correlations between LambdaR,intr(Re)
and kapparot(all), fspheroid(all), fhalo(all) derived in this paper from
TNG50 simulations to infer approximate values of kapparot(all),
fspheroid(all) and fhalo(all) based on LambdaR,intr(Re).
The uncertainties associated with these empirical correlations, as determined
from TNG50 simulations in this paper, are 0.05, 0.09, and 0.13, respectively.
We also leverage the empirical correlations between LambdaR,intr(Re)
and kapparot(Re), fspheroid(Re), fhalo(Re) derived in this paper from
TNG50 simulations to infer approximate values of kapparot(Re),
fspheroid(Re) and fhalo(Re) based on LambdaR,intr(Re).
The uncertainties associated with these empirical correlations, as determined
from TNG50 simulations in this paper, are 0.03, 0.1, and 0.185, respectively.
For the LambdaR,intr(Re) showing --- values, it means the galaxy's
inclination or ellipticity is inaccurate, or the galaxy fails to meet the
axisymmetric assumption, making it impossible to deduce the intrinsic
ellipticity from the observed ellipticity and inclination.
Among the 193 ATLAS^3D galaxies, 15 galaxies have LambdaR,intr(Re) as ---.
Among the 933 MaNGA galaxies, 97 galaxies have LambdaR,intr(Re) as ---.
For ATLAS3D, the inclination are adopted from Cappellari et al.
(2013MNRAS.432.1709C 2013MNRAS.432.1709C), the ellipticity measured within Re are adopted from
Emsellem et al. (2011MNRAS.414..888E 2011MNRAS.414..888E, cat. J/MNRAS/414/888),
and the stellar spin parameter Lambda_R(Re) measured within Re are
adopted from Emsellem et al. (2011MNRAS.414..888E 2011MNRAS.414..888E, cat. J/MNRAS/414/888).
For MaNGA, The inclination are adopted from Zhu et al. (2023MNRAS.522.6326Z 2023MNRAS.522.6326Z).
the ellipticity measured within Re are adopted from Zhu et al.
(2023MNRAS.522.6326Z 2023MNRAS.522.6326Z), and the stellar spin parameter Lambda_R(Re) measured
within Re are adopted from Zhu et al. (2023MNRAS.522.6326Z 2023MNRAS.522.6326Z).
Note (2): The new kinematic classification adopted from this paper.
FR = a new kinematic classification as fast rotator (Lambda_R,intr(Re)≥0.4)
SR = a new kinematic classification as slow rotator (Lambda_R,intr(Re)<0.4)
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Acknowledgements:
Wenyu Zhong, 34820210156874(at)stu.xmu.edu.cn
(End) W. Zhong [Dep. Astron., Xiamen Univ.], P. Vannier [CDS] 19-Feb-2026