J/MNRAS/487/3776 NGC 3115 Stellar Populations and Kinematics (Poci+, 2019)
Combining stellar populations with orbit-superposition dynamical modelling:
the formation history of the lenticular galaxy NGC 3115.
Poci A., McDermid R. M., Zhu L., van de Ven G.
<Mon. Not. R. Astron. Soc. 487, 3776-3796 (2019)>
=2019MNRAS.487.3776P 2019MNRAS.487.3776P (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, nearby ; Morphology ; Radial velocities ;
Velocity dispersion
Keywords: galaxies: elliptical and lenticular, cD - galaxies: structure -
galaxies: kinematics and dynamics - galaxies: stellar content -
galaxies: individual: NGC 3115
Abstract:
We present a combination of the Schwarzschild orbit-superposition
dynamical modelling technique with the spatially-resolved mean stellar
age and metallicity maps to uncover the formation history of galaxies.
We apply this new approach to a remarkable 5-pointing mosaic of
VLT/MUSE observations obtained by Guerou et al. (2016A&A...591A.143G 2016A&A...591A.143G,
Cat. J/A+A/591/A143) extending to a maximum galactocentric distance of
∼120'' (5.6kpc) along the major axis, corresponding to ∼2.5R_e.
Our method first identifies 'families' of orbits from the dynamical
model that represent dynamically distinct structures of the galaxy.
Individual ages and metallicities of these components are then fit for
using the stellar-population information. Our results highlight
components of the galaxy that are distinct in the combined stellar
dynamics/populations space, which implies distinct formation paths.
We find evidence for a dynamically-cold, metal-rich disk, consistent
with a gradual in-situ formation. This disk is embedded in a
generally-old population of stars, with kinematics ranging from
dispersion-dominated in the centre to an old, diffuse, metal-poor
stellar halo at the extremities. We find also a direct correlation
between the dominant dynamical support of these components, and their
associated age, akin to the relation observed in the Milky Way. This
approach not only provides a powerful model for inferring the
formation history of external galaxies, but also paves the way to a
complete population-dynamical model.
Description:
This catalogue is a suite of data products derived from full-spectral-
fitting techniques. It includes stellar kinematics, parametrised by an
LOSVD using the first six Gauss-Hermite coefficients, and associated
errors. It also includes luminosity-weighted SSP-equivalent mean
stellar age and metallicity measurements, and associated errors.
Additionally, it contains the subsequent stellar mass-to-light ratio
assuming a Kroupa (2002Sci...295...82K 2002Sci...295...82K) IMF in V-band.
Objects:
----------------------------------------------------
RA (2000) DE Designation(s)
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10 05 13.98 -07 43 06.9 NGC 3115 = LEDA 29265
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
popul.dat 157 4881 NGC 3115 populations
mge.dat 31 16 *NGC 3115 mass surface density MGE (table A1)
kinemat.dat 320 4881 NGC 3115 kinematics
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Note on mge.dat: MGE fit to the mass surface-density 'image', which requires
16 Gaussians in order to accurately describe the mass distribution.
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See also:
J/A+A/564/L3 : NGC 3115 globular clusters JHK photometry (Cantiello+, 2014)
J/AJ/148/32 : Globular cluster candidates in NGC 3115 (Jennings+, 2014)
J/ApJ/808/19 : Megasecond Chandra XVP obs. of NGC3115. II. (Lin+, 2015)
J/A+A/591/A143 : NGC 3115 MUSE images (Guerou+, 2016)
Byte-by-byte Description of file: popul.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 F6.1 --- N Voronoi bin number
8- 29 F22.18 arcsec xbin Voronoi bin x centroid
31- 52 F22.18 arcsec ybin Voronoi bin y centroid
54- 72 F19.16 Gyr ageLW luminosity-weighted mean stellar age
74- 92 F19.17 Gyr e_ageLW luminosity-weighted mean stellar age error
94-116 E23.20 [-] metalLW luminosity-weighted mean stellar metallicity
118-138 F21.19 [-] e_metalLW luminosity-weighted mean stellar metallicity
error
140-157 F18.16 Msun/Lsun (M/LV)KB V-band M/L assuming Kroupa
(2002Sci...295...82K 2002Sci...295...82K) IMF
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Byte-by-byte Description of file: mge.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 F13.5 Msun/pc+2 SDens Projected surface mass density
15- 23 F9.5 arcsec Disp Projected dispersion
25- 31 F7.5 --- AxisRatio Projected axis ratio
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Byte-by-byte Description of file: kinemat.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 6 F6.1 --- N Voronoi bin number
8- 29 F22.18 arcsec xbin Voronoi bin x centroid
31- 52 F22.18 arcsec ybin Voronoi bin y centroid
54- 71 F18.14 km/s V Mean velocity
73- 91 F19.16 km/s e_V Mean velocity error
93-111 F19.15 km/s s Velocity dispersion
113-132 F20.17 km/s e_s Velocity dispersion error
134-156 E23.20 --- h3 h3 coefficient
158-179 E22.20 --- e_h3 h3 coefficient error
181-203 E23.20 --- h4 h4 coefficient
205-226 E22.20 --- e_h4 h4 coefficient error
228-250 E23.20 --- h5 h5 coefficient
252-273 E22.20 --- e_h5 h5 coefficient error
275-297 E23.20 --- h6 h6 coefficient
299-320 E22.20 --- e_h6 h6 coefficient error
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Acknowledgements:
Adriano Poci, adriano.poci(at)students.mq.edu.au
(End) Adriano Poci [Macquarie University], Patricia Vannier [CDS] 21-Jul-2019