Single Stellar Populations models in the Near-Infrared range
R. F. Peletier, S. C. Trager
IoA @ Cambridge
February 26, 2014
Sofia Meneses-Goytia
Motivation
Galactic evolution of “far away” galaxies Close enough to obtain integrated spectra
Light at different wavelengths gives information about the stars: In the NIR cool stars
Prepare for ELT´s, JWST Moving to NIR observations requires NIR models
2
Spectral Energy Distribution (SED)
SSP spectra
Analyze galaxy spectra adapting models to the characteristics of the data Smoothed to match the resolution of the data and galaxy internal
velocity dispersion
Full spectrum comparison of a particular set of features, measured on both, the galaxy spectrum and the SSP SEDs.
Insight into Ages Metallicities Abundance ratios IMF (not easily probed in resolved systems) Kinematic parameters determination
3
Near–Infrared range Importance Early type galaxies / old populations Contribution of AGB and late phases often dominate the
spectra
Break age/metallicity degeneracy (potentially)
Disadvantages Atmospheric telluric absorption Varying IR background
4
Basic outline 5
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Fits
Basic outline 6
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Fits
Stellar spectral library IRTF spectral library Rayner et al. 2009 and Cushing et al. 2005
210 stars (292 spectra)
FWHM varies with wavelength
0.8 to 2.5 μm or 5.2 μm
F, G, K and M stars
7
Meneses-Goytia et al. 2014b (submitted)
-3.0-2.5-2.0-1.5-1.0-0.50.00.5
3000450060007500
[Z/Z
!]
Teff (K)
-1.00.01.02.03.04.05.0
log
g
-1.00.01.02.03.04.05.0
log
g
-3.0-2.5-2.0-1.5-1.0-0.50.00.5
[Z/Z
!]
Parameters determination Full-spectrum fitting
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Color-temperature relations
Testing the flux calibration 9
Meneses-Goytia et al. 2014a (submitted) More…
Determining the resolution 10
Meneses-Goytia et al. 2014a (submitted)
More…
The SSP models 11
Re
lativ
e fl
ux
Wavelength (μm)
Population of stars with a common age and metallicity For each star
Mass Atmospheric parameters Spectrum Stellar class + type
Total (stellar) mass of the population
Meneses-Goytia et al. 2014a (submitted)
Their characteristics 12
Meneses-Goytia et al. 2014a (submitted)
SED of SSP models 13
Meneses-Goytia et al. 2014b (submitted)
0.96
0.98
1.00
1.02
1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4
Ratio
s
Wavelength (!m)
GirS / MarSBaSS / MarSBaSS / GirS
1.0
2.0
3.0
F/F 1
.65 !
m+c
onst
ant
MarSGirS
BaSSCa Fe PP C Pa Na Si C Ca Ni Pa Al Si Fe K Si C Ti M
gFe Ni Si
Ca Fe Mg
Ca Al K
Br C C Ni Si Fe Al Si Br Na Fe Ca Mg
CO
I I II I
I I I I I
I I I I I I I I I I I
I I I I I I
I I II I I I I
I I I I
14
0.2
0.3
1 10
(H-K
)
Age(Gyr)
0.6
0.7
0.8
(J-H
)
0.8
1.0
1.2
(J-K
)
MarS
- 0.7 dex- 0.4 dex+ 0.0 dex+ 0.2 dex
G04P08
1 10Age (Gyr)
GirS
1 10Age (Gyr)
BaSS
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Integrated colors from the SEDs
Integrated colors from the SEDs 15
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0.1
0.2
0.3
0.62 0.67 0.72 0.77
(H-K
)
(J-H)
0.1
0.2
0.3
0.82 0.92 1.02
(H-K
)
(J-K)
0.62
0.67
0.72
0.77
(J-H
)MarS
F78- 0.7 dex- 0.4 dex+ 0.0 dex+ 0.2 dex
2 Gyr 7 Gyr
14 Gyr
0.62 0.67 0.72 0.77(J-H)
0.82 0.92 1.02(J-K)
GirS
0.62 0.67 0.72 0.77(J-H)
0.82 0.92 1.02(J-K)
BaSS
Indices from the SEDs 16
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1.16
1.21
1.26
1 10
DC
O (m
ag)
Age (Gyr)
0.1
0.1
0.3
Mg
I (Å)
1.8
2.3
2.8
Ca
I (Å)
0.9
1.4
1.9Fe
I (Å
)1.8
2.3
2.8
3.3
Na
I (Å)
MarS
0.7 dex 0.4 dex
+ 0.0 dex+ 0.2 dex
1 10Age (Gyr)
GirS
1 10Age (Gyr)
BaSS
Comparison with other authors 17
Meneses-Goytia et al. 2014b (submitted)
2.20
2.40
2.60
2.80
3.00
3.20
3.40
3.60
1.13 1.14 1.15 1.16 1.17 1.18 1.19 1.20 1.21 1.22 1.23
Na I
DCO
MQ09MarSGirS
BaSS2 Gyr7 Gyr
14 GyrC12
3 Gyr7 Gyr
14 Gyr
0.1
0.2
0.3
1 10
(H-K
)
Age (Gyr)
0.6
0.7
0.8
(J-H
)
0.8
1.0
(J-K
)
MarSGirS
BaSSV10C12M09
BC03
More…
Comparison with early type galaxies
Mármol-Queraltó et al. 2009 14 bright elliptical
galaxies (12 field, 2 Fornax)
2.19 to 2.31 μm FWHM 7.14 Å
Silva et al. 2008 9 Fornax galaxies 2.19 to 3.43 μm FWHM 6.90 Å
18
F (a
rbitr
ary
un
its)
Indices from the SEDs 19
1.5
2.5
3.5
4.5
0.65 0.75
Na
I
(J H)
1.18
1.22
0.8 1.0 1.1
DC
O
(J Ks)
MarS
MQ09MQ09 Fnx
0.7 dex 0.4 dex
+ 0.0 dex+ 0.2 dex
2 Gyr7 Gyr
14 Gyr
0.65 0.75(J H)
0.8 1.0 1.1(J Ks)
GirS
0.65 0.75(J H)
0.8 1.0 1.1(J Ks)
BaSS
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Comparisons – an example 20
Through full spectral fitting using pPXF (Cappellari & Emsellem 2004)
– 0.40 dex ~ 4 Gyr
Meneses-Goytia et al. 2014c (in prep)
NGC3605
2.20 2.22 2.24 2.26 2.28 2.30Wavelength, µm
0.5
0.6
0.7
0.8
0.9
1.0
1.1
Rela
tive flu
x
Velocity dispersion 21
σ (
km/s
) –
pre
sen
t w
ork
σ (km/s) – Mármol-Queralto et al. 2009 σ (km/s) – HYPERLEDA
Meneses-Goytia et al. 2014c (in prep)
Conclusions SED modeling in the NIR works
Velocity dispersions agree with established methods in the optical
Current models not sensitive to young populations Insufficient parameter coverage IRTF Intrinsic sensitivity NIR Uncertainties due to AGB With a combination with optical colors (?)
22
Thank you
IoA @ Cambridge
February 26, 2014
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