J/MNRAS/481/5580 The formation sequence of S0 galaxies (Fraser-McKelvie+, 2018)
SDSS-IV MaNGA: the formation sequence of S0 galaxies.
Fraser-McKelvie A., Aragon-Salamanca A., Merrifield M., Tabor M.,
Bernardi M., Drory N., Parikh T., Argudo-Fernandez M.
<Mon. Not. R. Astron. Soc., 481, 5580-5591 (2018)>
=2018MNRAS.481.5580F 2018MNRAS.481.5580F (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Morphology ; Abundances
Keywords: galaxies: elliptical and lenticular - galaxies: evolution -
galaxies: general - galaxies: stellar content
Abstract:
Gas stripping of spiral galaxies or mergers are thought to be the
formation mechanisms of lenticular galaxies. In order to determine the
conditions in which each scenario dominates, we derive stellar
populations of both the bulge and disc regions of 279 lenticular
galaxies in the MaNGA survey. We find a clear bimodality in stellar
age and metallicity within the population of S0s and this is strongly
correlated with stellar mass. Old and metal-rich bulges and discs
belong to massive galaxies, and young and metal-poor bulges and discs
are hosted by low-mass galaxies. From this we conclude that the bulges
and discs are co-evolving. When the bulge and disc stellar ages are
compared, we find that the bulge is almost always older than the disc
for massive galaxies (M*>1010M☉). The opposite is true for
lower mass galaxies. We conclude that we see two separate populations
of lenticular galaxies. The old, massive, and metal-rich population
possess bulges that are predominantly older than their discs, which we
speculate may have been caused by morphological or inside-out
quenching. In contrast, the less massive and more metal-poor
population have bulges with more recent star formation than their
discs. We postulate they may be undergoing bulge rejuvenation (or disc
fading), or compaction. Environment does not play a distinct role in
the properties of either population. Our findings give weight to the
notion that while the faded spiral scenario likely formed low-mass
S0s, other processes, such as mergers, may be responsible for
high-mass S0s.
Description:
279 lenticular galaxies were selected from the MaNGA survey's MaNGA
product launch 5 (MPL-5), consisting of 2778 galaxy data cubes
observed from March 2014 to May 2016. The MaNGA galaxy survey is an
IFS survey that aims to observe ∼10000 galaxies by 2020 (Bundy et al.
2015ApJ...798....7B 2015ApJ...798....7B; Drory et al. 2015AJ....149...77D 2015AJ....149...77D) and is a
project of SDSS-IV (Blanton et al. 2017AJ....154...28B 2017AJ....154...28B) using the 2.5m
telescope at the Apache Point Observatory (Gunn et al.
2006AJ....131.2332G 2006AJ....131.2332G) and BOSS spectrographs (Smee et al.
2013AJ....146...32S 2013AJ....146...32S).
All galaxy observations have wavelength coverage of ∼3500-10000Å,
spectral resolution R ∼2000 (which gives an instrumental resolution of
∼60km/s), and an effective spatial resolution of 2.5arcsec (full width
at half-maximum) after combining dithered observations; the sample
lies within the redshift range 0.01<z<0.15 (Yan et al.
2016AJ....152..197Y 2016AJ....152..197Y). Observations are reduced by a data reduction
pipeline (Law et al. 2016AJ....152...83L 2016AJ....152...83L; Yan et al.
2016AJ....151....8Y 2016AJ....151....8Y) and made available as a single data cube per
galaxy.
The traditional morphological definition of an S0 is a galaxy that
contains a bulge and a disc, but lacks spiral arms. However, this
definition can struggle to distinguish between S0s and ellipticals.
For this reason, we choose to employ kinematic selection techniques in
tandem with a traditional morphological classification scheme. From
the 2778 galaxies in MPL-5, this procedure selects 279 lenticulars,
the properties of which are summarized in Table A1. Table A2 lists the
bulge and disc H β, Mgb, Fe5270, and Fe5335 measurements for each
galaxy.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 116 279 Physical properties and derived quantities of
the lenticular galaxies used in this work
tablea2.dat 74 279 Measured spectral indices for lenticular
galaxies in this work
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- ID MaNGA Plate IFU
12- 13 I2 h RAh Right ascension (J2000)
15- 16 I2 min RAm Right ascension (J2000)
18- 19 I2 s RAs Right ascension (J2000)
21 A1 --- DE- Declination sign (J2000)
22- 23 I2 deg DEd Declination (J2000)
25- 26 I2 arcmin DEm Declination (J2000)
28- 31 F4.1 arcsec DEs Declination (J2000)
33- 38 F6.4 --- z Redshift (1)
40- 47 F8.4 10+10Msun Mstar Stellar mass (1)
49- 52 F4.2 --- b/a Axis ratio (2)
54- 57 F4.2 --- B/T Bulge to total ratio (2)
59- 63 F5.2 --- Rb Bulge effective radius (2)
65- 68 F4.2 --- nb Sersic index, bulge component (2)
70- 75 F6.3 [Gyr] AgeBulge ?=- Bulge stellar age
77- 82 F6.3 [Gyr] AgeDisc ?=- Disc stellar age
84- 90 F7.3 --- [Z/H]B ?=999 Bulge metallicity
92- 98 F7.3 --- [Z/H]D ?=999 Disc metallicity
100-107 F8.3 --- Qlss ?=-999 Tidal strength paramater (3)
109-116 F8.3 --- etak ?=-999 Projected galaxy number density (3)
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Note (1): Values obtained from the NASA Sloan Atlas
Note (2): Values obtained from the free nb model table of bulge and disc
measurements of Simard et al. (2011ApJS..196...11S 2011ApJS..196...11S,
Cat. J/ApJS/196/11)
Note (3): Derived using the method of Argudo-Fernandez et al.
(2015A&A...578A.110A 2015A&A...578A.110A).
The tidal strength parameter, Qlss, is an estimation of the local
tidal strength at 1Mpc, and gives an indication of how strongly nearby
galaxies are perturbing the galaxy in question. ηk is the
projected density to the 5th nearest neighbour.
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- ID MaNGA Plate IFU
12- 18 F7.3 0.1nm HbetaB ?=999 Bulge H β Lick index
20- 26 F7.3 0.1nm HbetaD ?=999 Disc H β Lick index
28- 34 F7.3 0.1nm MgbB ?=999 Bulge Mgb Lick index
36- 42 F7.3 0.1nm MgbD ?=999 Disc Mgb Lick index
44- 50 F7.3 0.1nm Fe5270B ?=999 Bulge Fe5270 Lick index
52- 58 F7.3 0.1nm Fe5270D ?=999 Disc Fe5270 Lick index
60- 66 F7.3 0.1nm Fe5335B ?=999 Bulge Fe5335 Lick index
68- 74 F7.3 0.1nm Fe5335D ?=999 Disc Fe5335 Lick index
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 17-Jun-2022