VI/109 Population Synthesis Models at very low metallicities (Schaerer, 2003)
The transition from Population III to normal galaxies:
Lyα and HeII λ1640 emission and the ionising properties of
high redshift starburst galaxies
Schaerer D.
<Astron. Astrophys. 397, 527 (2003)>
=2003A&A...397..527S 2003A&A...397..527S
ADC_Keywords: Models, atmosphere ; Models, evolutionary ; Populations, stellar ;
Spectra, ultraviolet
Keywords: cosmology: early Universe - galaxies: stellar content -
stars: general - stars: fundamental parameters - stars: atmospheres
Abstract:
Using new sets of stellar evolution models at very low metallicities
(Z=10-7; 10-5) and previously published grids we examine spectral
properties of the ionising continua, the Lyman-break, and the
Lyα and He1640 recombination lines in starbursts. The
metallicity dependence of these properties, especially the transition
from primordial galaxies (Population III) to currently observed
metallicities, is examined for various IMFs and star formation
histories.
Description:
All the models used are included in the tar file "models.tar",
which contains a README file describing the file naming conventions
depending on the values of the parameters (see note (G1)). There are
five different types of output for each set of parameter values,
designated by a number between 20 and 24, which are also presented in
tabular form in the files type20.dat to type24.dat.
All the quantities are normalised to a total burst mass of 1solMass;
note that different normalisation conventions may be found elsewhere,
e.g. Starburst99 (Leitherer et al., 1999ApJS..123....3L 1999ApJS..123....3L) which is
normalised to a burst of 106solMass.
The models are computed with the pop-iso-25 code Version 2.5.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
initial.dat 135 9 Initial parameters of the models
type20.dat 237 74289 Main output (file corresponding to output described
in Schaerer & Vacca, 1998ApJ...497..618S 1998ApJ...497..618S) plus
additional quantities (last four columns)
type21.dat 233 74289 Output related to Wolf-Rayet stars (file
corresponding to output described in
Schaerer & Vacca, 1998ApJ...497..618S 1998ApJ...497..618S)
type22.dat 210 74289 Nebular recombination lines - NEW V2.4
type23.dat 142 74289 Colors (filter bandpasses as in Starburst99
(Leitherer et al., 1999ApJS..123....3L 1999ApJS..123....3L)
type24.dat 140 74289 UV spectral information
models.tar 1570 375666 All the available files/sets
--------------------------------------------------------------------------------
See also:
http://webast.ast.obs-mip.fr/sfr/ : Models homepage
Byte-by-byte Description of file: initial.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Z Code for metallicity Z, indicates the
model groups, see note (G1)
7- 11 F5.1 solMass WRmass WR mass limit
13- 16 F4.1 [Sun] [M/H] Input metallicity content of Kurucz model
18- 20 F3.1 km/s Vturb Input turbulent velocity of Kurucz model
22- 25 F4.2 --- L/H Input convective parameter of Kurucz model
27- 29 A3 --- WRMod [YES NO] Include WR models
31- 33 A3 --- CoStarRad [YES NO] use CoStar WR radii
34- 36 A3 --- CoStarMod [YES NO] CoStar models
37- 42 A6 --- n_CoStarMod [(M>20)] (M>20): (YES for masses≥20.000)
44- 46 A3 --- TLUSTYMod [YES NO] use TLUSTY models
48-147 A100 --- Tracks Tracks used
--------------------------------------------------------------------------------
Byte-by-byte Description of file: type20.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Z Code for metallicity Z (G1)
6 A1 --- --- [_]
7- 9 A3 --- IMF [sal] IMF type (G1)
10 A1 --- --- [_]
11- 13 I3 solMass mup Upper mass cut-off of IMF in M☉ (G1)
14 A1 --- --- [_]
15- 17 I3 solMass low Lower mass cut-off of IMF in M☉ (G1)
18 A1 --- --- [_]
19- 21 A3 --- sfh Code for star formation history (G1)
(cs1, cs3, cs4, is1, is3)
22- 24 A3 --- --- [.20] (G1)
29- 33 F5.3 [yr] log(Age) Age
35- 41 F7.3 mag Mbol Bolometric magnitude
44- 49 F6.3 [s-1] log(Q0) Lyman continuum photon flux (Q0=QH)
52- 57 F6.3 [s-1] log(Q1) He0 ionising photon flux (Q1=QHe)
59- 65 F7.3 [s-1] log(Q2) He+ ionising photon flux (Q0=QHe+)
68- 75 E8.3 --- NOstar Number of O stars
77- 83 E7.2 --- WR/(WR+O) Ratio of WR to WR+O stars
85- 91 E7.2 --- WR/O Ratio of WR to O stars
93- 99 E7.2 --- WNL/(WR+O) Ratio of WNL (late WN) to WR+O stars
101-107 E7.2 --- WNE/(WR+O) Ratio of WNE (early WN) to WR+O stars
109-115 E7.2 --- WC/(WR+O) Ratio of WC to WR+O stars
118-124 F7.3 0.1nm EWHb Nebular Hβ equivalent width (G2)
126-133 E8.3 10-7W LHb Nebular Hβ luminosity (G2)
136-142 F7.3 0.1nm EWHeI Nebular HeI 4471 equivalent width
(CAUTION: Saturation effect !) (G2)
144-151 E8.3 --- LHeI Relative Nebular HeI 4471 luminosity
(in Hβ unit) (G2)
154-160 F7.3 0.1nm EWHeII Nebular HeII 4686 equivalent width (G2)
162-169 E8.3 --- LHeII Nebular HeII 4686 luminosity
(in Hβ unit) (G2)
173-178 F6.3 0.1nm EWWR WR bump (CIII/IV 4650 + HeII 4686)
equivalent width
180-187 E8.3 --- LWR WR bump (CIII/IV 4650 + HeII 4686)
luminosity (in Hβ unit) (G2)
191-196 F6.3 0.1nm EWCI CI V-WR equivalent width
198-205 E8.3 --- LCI CI V-WR luminosity (in Hβ unit) (G2)
208-213 F6.3 mag Balmer Balmer jump, defined as
-2.5*log(F(3640Å)/F(3650Å)
216-221 F6.3 [s-1] log(QH2) Ionising photon flux in Lyman-Werner band
(QH2=QLW) (G3)
224-229 F6.3 eV E(Q) Average energy per photon in Lyman-continuum
232-237 F6.3 eV E(QHe+) ? Average energy per photon with E>54eV
--------------------------------------------------------------------------------
Byte-by-byte Description of file: type21.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Z Code for metallicity Z (G1)
6 A1 --- --- [_]
7- 9 A3 --- IMF [sal] IMF type (G1)
10 A1 --- --- [_]
11- 13 I3 solMass mup Upper mass cut-off of IMF in M☉ (G1)
14 A1 --- --- [_]
15- 17 I3 solMass low Llower mass cut-off of IMF in M☉ (G1)
18 A1 --- --- [_]
19- 21 A3 --- sfh Code for star formation history (G1)
22- 24 A3 --- --- [.21] (G1)
29- 33 F5.3 [yr] log(Age) Age
36- 38 F3.1 --- WNLType Average WNL subtype (late WN)
43- 45 F3.1 --- WCType Average WC subtype
48- 54 F7.2 0.1nm EWHa Nebular Hα equivalent width (G2)
56- 63 E8.3 --- LHa Nebular Hα luminosity
(in Hβ unit) (G2)
66- 71 F6.2 0.1nm EWHb Nebular Hβ equivalent width (G2)
73- 80 E8.3 10-7W LHb Nebular Hβ luminosity (G2)
85- 88 F4.2 0.1nm EWHe1640 Stellar He1640 equivalent width
90- 97 E8.3 --- LHe Stellar He1640 luminosity (in Hβ unit) (G2)
102-105 F4.2 0.1nm EWN4640 Stellar N4640 equivalent width
107-114 E8.3 --- LN Stellar N4640 luminosity (in Hβ unit) (G2)
118-122 F5.2 0.1nm EWC4650 Stellar C4650 equivalent width
124-131 E8.3 --- LC4650 Stellar C4650 luminosity (in Hβ unit) (G2)
135-139 F5.2 0.1nm EWHe4686 Stellar He4686 equivalent width
141-148 E8.3 --- LHe4686 Stellar He4686 luminosity (in Hβ unit) (G2)
153-156 F4.2 0.1nm EWH4861 Stellar H4861 equivalent width
158-165 E8.3 --- LH4861 Stellar H4861 luminosity (in Hβ unit) (G2)
169-173 F5.2 0.1nm EWC5696 Stellar C5696 equivalent width
175-182 E8.3 --- LC5696 Stellar C5996 luminosity (in Hβ unit) (G2)
186-190 F5.2 0.1nm EWC5808 Stellar C5808 equivalent width
192-199 E8.3 --- LC5808 Stellar C5808 luminosity (in Hβ unit) (G2)
203-207 F5.2 0.1nm EWH6560 Stellar H6560 equivalent width
209-216 E8.3 --- LH6560 Stellar H6560 luminosity (in Hβ unit) (G2)
221-224 F4.2 0.1nm EWHe5412 Stellar He5412 equivalent width
226-233 E8.3 --- LHe5412 Stellar He5412 luminosity (in Hβ unit) (G2)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: type22.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Z Code for metallicity Z (G1)
6 A1 --- --- [_]
7- 9 A3 --- IMF [sal] IMF type (G1)
10 A1 --- --- [_]
11- 13 I3 solMass mup Upper mass cut-off of IMF in M☉ (G1)
14 A1 --- --- [_]
15- 17 I3 solMass low Lower mass cut-off of IMF in M☉ (G1)
18 A1 --- --- [_]
19- 21 A3 --- sfh Code for star formation history (G1)
22- 24 A3 --- --- [.22] (G1)
29- 33 F5.3 [yr] log(Age) Age
36- 41 F6.3 [s-1] log(Q0) Lyman continuum photon flux (Q0=QH)
44- 49 F6.3 [s-1] log(Q1) He0 ionising photon flux (Q1=QHe)
51- 57 F7.3 [s-1] log(Q2) He+ ionising photon flux (Q0=QHe+)
59- 66 E8.3 10-7W LHb Hβ luminosity (G2)
68- 75 F8.3 0.1nm EWHLya Lymanα equivalent width (G2)
77- 84 E8.3 --- IHLy Lymanα Intensity relative to
Hβ (G2)
86- 93 F8.3 0.1nm EWHa Hα equivalent width (G2)
95-102 E8.3 --- IHa Hα intensity relative to Hβ (G2)
105-111 F7.3 0.1nm EWHb Hβ equivalent width (G2)
113-120 E8.3 --- IHb [1.00E+00] Hβ intensity relative
to Hβ (G2)
123-129 F7.3 0.1nm EWHeI HeI 4471 equivalent width
(CAUTION: Saturation effect !) (G2)
131-138 E8.3 --- IHeI HeI 4471 intensity relative to Hβ (G2)
142-147 F6.3 0.1nm EWHeII1640 HeII1640 equivalent width (G2)
149-156 E8.3 --- IHeII1640 HeII1640 intensity relative to Hβ (G2)
159-165 F7.3 0.1nm EWHeII4686 HeII4686 equivalent width (G2)
167-174 E8.3 --- IHeII4686 HeII4686 intensity relative to Hβ (G2)
178-183 F6.3 0.1nm EWHeII3203 HeII3203 equivalent width (G2)
185-192 E8.3 --- IHeII3203 HeII3203 intensity relative to Hβ (G2)
197-201 F5.3 0.1nm EWHeII4541 HeII4541 equivalent width (G2)
203-210 E8.3 --- IHeII4541 HeII4541 intensity relative to Hβ
--------------------------------------------------------------------------------
Byte-by-byte Description of file: type23.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Z Code for metallicity Z (G1)
6 A1 --- --- [_]
7- 9 A3 --- IMF [sal] IMF type (G1)
10 A1 --- --- [_]
11- 13 I3 solMass mup Upper mass cut-off of IMF in M☉ (G1)
14 A1 --- --- [_]
15- 17 I3 solMass low Llower mass cut-off of IMF in M☉ (G1)
18 A1 --- --- [_]
19- 21 A3 --- sfh Code for star formation history (G1)
22- 24 A3 --- --- [.23] (G1)
29- 37 E9.3 [yr] log(Age) Age
38- 43 F6.3 mag (130-V) (130-V) colour index
46- 51 F6.3 mag (210-V) (210-V) colour index
54- 59 F6.3 mag (U-B) (U-B) colour index
62- 67 F6.3 mag (B-V) (B-V) colour index
70- 75 F6.3 mag (V-R) (V-R) colour index
78- 83 F6.3 mag (V-I) (V-I) colour index
86- 91 F6.3 mag (V-J) (V-J) colour index
94- 99 F6.3 mag (V-H) (V-H) colour index
102-107 F6.3 mag (V-K) (V-K) colour index
110-115 F6.3 mag (V-L) (V-L) colour index
118-124 F7.3 mag VMAG Absolute V magnitude
127-133 F7.3 mag BMAG Absolute B magnitude
136-142 F7.3 mag Mbol Bolometric magnitude
--------------------------------------------------------------------------------
Byte-by-byte Description of file: type24.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Z Code for metallicity Z (G1)
6 A1 --- --- [_]
7- 9 A3 --- IMF [sal] IMF type (G1)
10 A1 --- --- [_]
11- 13 I3 solMass mup Upper mass cut-off of IMF (G1)
14 A1 --- --- [_]
15- 17 I3 solMass low Llower mass cut-off of IMF (G1)
18 A1 --- --- [_]
19- 21 A3 --- sfh Code for star formation history (G1)
22- 24 A3 --- --- [.24] (G1)
29- 33 F5.3 [yr] log(Age) Age
37- 43 F7.3 mag Mbol Bolometric magnitude
49- 54 F6.3 [10-6W/nm] log(L15SB) Average UV luminosity at 1500Å
(over ± 20Å band), in erg/s/Å
60- 65 F6.3 [10-6W/nm] log(L1500) Average UV luminosity at 1500Å
(over ±150Å band), in erg/s/Å
71- 76 F6.3 [10-6W/nm] log(L2800) Average UV luminosity at 2800Å
(over ±280Å band), in erg/s/Å
79- 84 F6.3 --- beta1550 UV slope 1300-1800Å using
STELLAR + NEBULAR cont. emission (1)
87- 92 F6.3 --- beta2500 UV slope 2200-2800Å using
STELLAR + NEBULAR cont. emission (1)
95-100 F6.3 --- beta2000 UV slope 1800-2200Å using
STELLAR + NEBULAR cont. emission (1)
103-108 F6.3 --- beta1550* UV slope 1300-1800Å using pure
STELLAR emission (1)
111-116 F6.3 --- beta2500* UV slope 2200-2800Å using pure
STELLAR emission (1)
119-124 F6.3 --- beta2000* UV slope 1800-2200Å using pure
STELLAR emission (1)
127-132 F6.3 [10-6W/nm] log(L900) Average luminosity 912- in erg/s/Å (2)
135-140 F6.3 [---] log(Lybrk) Lyman-break amplitude Lybrk=912+/912-
--------------------------------------------------------------------------------
Note (1): The slope beta is defined by F(λ)∝~λβ
Note (2): Where 912+ is the average flux in F(λ) units
over 1080-1120Å, and 912- the same over 870-900Å
--------------------------------------------------------------------------------
Global notes:
Note (G1): General nomenclature of filenames:
* For PopIII models : pop3tttimfmuplow_sfh.xx
* Other metallicities : e*imfmuplowsfh.xx
where:
e* = Metallicity Z, as
e-70: Z=1.e-7
e-50: Z=1.e-5
e0004: Z=0.0004
e001: Z=0.001
e004: Z=0.004
e008: Z=0.008
e020: Z=0.020
e040: Z=0.40
ttt = tracks used for PopIII models, as:
ge0: combined set of tracks with NO mass loss
mdt: including some tracks with mass loss
imf = IMF type, as:
sal: Salpeter law (α=2.35)
mup = upper mass cut-off of IMF (in solar masses)
low = lower mass cut-off of IMF (in solar masses)
sfh = star formation history, as:
is1: bursts up to ∼ 50-100 Myr (step of 0.1 Myr in age)
is3: bursts up to ∼ 10 Myr (step of 0.02 Myr in age)
cs1: constant star formation corresponding to is1 (*)
cs3: constant star formation corresponding to is3 (*)
cs4: constant star formation up to an age of 400 Myr (*)
(*) the timescale necessary to reach equilibrium may be long for o
some quantities, and the results with sfh=cs4 should be used
especially for the flux in the Lyman-Werner band log(QH2)
xx = file extension indicating the type of output, as:
20: Main output, as in 1998ApJ...497..618S 1998ApJ...497..618S
21: output for WR lines
22: recombination lines
23: colors of integrated population
24: UV luminosities, colors and slopes
Note (G2):
The NEBULAR emission line predictions given in the type20.dat and
type21.dat files are computed assuming an fixed electron temperature
Te=10kK, whereas the nebular continuous emission may be computed with a
variable Te ! Therefore these predictions may
i) be inconsistent and,
ii) differ from the ones given in the type22.dat file.
--> Use preferentially the predictions in type22.dat !!
--> The relative WR/Hbeta luminosities (=intensities) may simply
be rescaled by the ratio between the Hbeta luminosities given
in type20.dat/type21.dat. However, for these quantities the
differences are of the order of 6% only.
Note (G3): Important note for models with SFR=const:
Depending on the quantity of interest the timescale to reach
equilibrium (in other words an asymptotic value) may differ.
For these reasons various cases for SFR=const have been computed.
For most quantities the files with sfh=cs1 (up to age of 50-100Myr)
are appropriate. However, for the determination of the flux in the
Lyman-Werner band (QH2=QLW) for example, a longer timescale is
required. The files with sfh=cs4 (up to ages of 400Myr) should then
be used.
--------------------------------------------------------------------------------
Acknowledgements: Schaerer Daniel
References:
Schaerer, Properties of massive Pop III stars, 2002A&A...382...28S 2002A&A...382...28S
Leitherer et al., Starburst99, 1999ApJS..123....3L 1999ApJS..123....3L
Schaerer and Vacca, New models for WR and O stars, 1998ApJ...497..618S 1998ApJ...497..618S
(End) Patricia Bauer [CDS] 04-Nov-2002