J/A+A/635/A129 ATLAS3D sample metallicity and age gradients (Krajnovic+, 2020)
Formation channels of slow rotating early-type galaxies.
Krajnovic D., Ural U., Kuntschner H., Goudfrooij P., Wolfe M.,
Cappellari M., Davies R., de Zeeuw P.T., Duc P.-A., Emsellem E., Karick A.,
McDermid R.M., Mei S., Naab T.
<Astron. Astrophys. 635, A129 (2020)>
=2020A&A...635A.129K 2020A&A...635A.129K (SIMBAD/NED BibCode)
ADC_Keywords: Galaxy catalogs ; Abundances
Keywords: galaxies: elliptical and lenticular, cD - galaxies: evolution -
galaxies: formation - galaxies: kinematics and dynamics -
galaxies: structure - galaxies: stellar content
Abstract:
We study the evidence for a diversity of formation processes in
early-type galaxies by presenting the first complete volume-limited
sample of slow rotators with both integral-field kinematics from the
ATLAS3D Project and high spatial resolution photometry from the
Hubble Space Telescope. Analysing the nuclear surface brightness
profiles of 12 newly imaged slow rotators, we classify their light
profiles as core-less, and place an upper limit to the core size of
about 10 pc. Considering the full magnitude and volume-limited
ATLAS3D sample, we correlate the presence or lack of cores with
stellar kinematics, including the proxy for the stellar angular
momentum (λRe) and the velocity dispersion within one
half-light radius (σe), stellar mass, stellar age,
α-element abundance, and age and metallicity gradients. More
than half of the slow rotators have core-less light profiles, and they
are all less massive than 1011M☉. Core-less slow rotators show
evidence for counter-rotating flattened structures, have steeper
metallicity gradients, and a larger dispersion of gradient values
(Δ[Z/H]=-0.42±0.18) than core slow rotators
(Δ[Z/H]=-0.23±0.07). Our results suggest that core and
core-less slow rotators have different assembly processes, where the
former, as previously discussed, are the relics of massive
dissipation-less merging in the presence of central supermassive black
holes. Formation processes of core-less slow rotators are consistent
with accretion of counter-rotating gas or gas-rich mergers of special
orbital configurations, which lower the final net angular momentum of
stars, but support star formation. We also highlight core fast
rotators as galaxies that share properties of core slow rotators (i.e.
cores, ages, σe, and population gradients) and core-less slow
rotators (i.e. kinematics, λRe, mass, and larger spread in
population gradients). Formation processes similar to those for
core-less slow rotators can be invoked to explain the assembly of core
fast rotators, with the distinction that these processes form or
preserve cores.
Description:
We used two sets of observations based on spectroscopy and imaging.
The first set was obtained using the integral-field spectrograph
SAURON (Bacon et al. 2001MNRAS.326...23B 2001MNRAS.326...23B) as part of the ATLAS3D
survey (Cappellari et al., 2011, Cat. J/MNRAS/413/813) of nearby
early-type galaxies. In particular, we here present and make available
unpublished products of the stellar population analysis based on
McDermid et al. (2015, Cat. J/MNRAS/448/3484), pertaining to age,
metallicity, α-element abundances, and gradients of these
quantities. The second set of data is based on new HST imaging. The
ATLAS3D galaxies that were not analysed by Krajnovic et al. (2013,
Cat. J/MNRAS/433/2812) lacked HST observations suitable for extracting
nuclear surface brightness profiles.We selected all 12 remaining slow
rotators with the aim to complete this class with space-based
high-resolution imaging.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 37 260 Metallicity and age gradients for ATLAS3D sample
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See also:
J/MNRAS/413/813 : ATLAS3D project. I. (Cappellari+, 2011)
J/MNRAS/448/3484 : ATLAS3D Project. XXX (McDermid+, 2015)
J/MNRAS/433/2812 : ATLAS3D project. XXIII. (Krajnovic+, 2013)
Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Galaxy Name of the galaxy
11- 16 F6.3 --- D[Z/H] Metallicity gradient as defined by Eq.1 (1)
18- 22 F5.3 --- e_D[Z/H] Uncertainty on the gradient obtained from
weighted linear regression fits to the
metallicity profiles
24- 29 F6.3 --- DAge Age gradient as defined by Eq.1 (1)
31- 35 F5.3 --- e_DAge Uncertainty on the gradient obtained from
weighted linear regression fits to the
age profiles
37 I1 --- HST [0/2]? HST flag (2)
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Note (1): Eq. 1: Δ[Z/H]=∂[Z/H]/(∂log(R/Re))
Note (2): HST flag as follows:
1 = galaxies that were observed with HST and for which we were able to
extract surface brightness profiles
2 = galaxies with HST data and uncertain profiles
0 = galaxies with no HST data
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Acknowledgements:
Davor Krajnovic, dkrajnovic(at)aip.de
(End) Patricia Vannier [CDS] 31-Jan-2020