J/A+A/311/361 Evolution models of elliptical galaxies. II. (Tantalo+, 1996)
Spectro-photometric evolution of elliptical galaxies. II. Models with infall.
Tantalo R., Chiosi C., Bressan A., Fagotto F.
<Astron. Astrophys. 311, 361 (1996)>
=1996A&A...311..361T 1996A&A...311..361T (SIMBAD/NED BibCode)
ADC_Keywords: Models, evolutionary ; Photometry, UBVRIJKLMNH
Keywords: galaxies: ellipticals - galaxies: evolution -
galaxies: stellar content
Abstract:
In this paper we present new chemo-spectro-photometric models of
elliptical galaxies in which infall of primordial gas is allowed to
occur. They aim to simulate the collapse of a galaxy made of two
components, i.e. luminous material and dark matter. The mass of the
dark component is assumed to be constant in time, whereas that of the
luminous material is supposed to accrete at a suitable rate. They also
include the effect of galactic winds powered by supernova explosions
and stellar winds from massive, early-type stars. The models are
constrained to match a number of properties of elliptical galaxies,
i.e. the slope and mean colours of the colour-magnitude relation
(CMR), V versus (V-K), the UV excess as measured by the colour
(1550-V) together with the overall shape of the integrated spectral
energy distribution (ISED) in the ultraviolet, the relation between
the Mg2 index and (1550-V), the mass to blue luminosity ratio M/LB
as a function of the B luminosity, and finally the broad-band colours
(U-B), (B-V), (V-I), (V-K), etc. The CMR is interpreted as a
mass-metallicity sequence of old, nearly coeval objects, whose mean
age is 15Gyr. Assuming the law of star formation to be proportional to
Mgk(t) with k=1, the rate of star formation as function of time
starts small, grows to a maximum, and then declines thus easily
avoiding the excess of metal-poor stars found by BCF with the
closed-box scheme (the analog of the G-Dwarf Problem in the solar
vicinity). Owing to their stellar content, infall models can easily
reproduce all the basic data of the galaxies under examination. As far
as the UV excess is concerned, the same sources proposed by BCF are
found to hold also with the infall scheme. H-HB and AGB manque stars
of high metallicity play the dominant role, and provide a robust
explanation of the correlation between the (1550-V) colour and the
luminosity, mass and metallicity of the galaxies. Furthermore, these
models confirm the potential of the (1550-V) colour as an age
indicator in cosmology as already suggested by BCF. In the rest frame
of a massive and metal-rich elliptical galaxy, this colour suffers
from one major variation: at the onset of the so-called H-HB and
AGB-manque stars (age about 5.6Gyr). This transition occurs at
reasonably small red-shifts and therefore could be detected with the
present-day instrumentation.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2 119 281 Integrated colors of single stellar populations
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See also:
J/A+A/335/823 : Evolution models of elliptical galaxies. III. (Tantalo+ 1998)
Byte-by-byte Description of file: table2
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Bytes Format Units Label Explanations
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1- 6 F6.4 --- Z Metallicity
9- 15 F7.4 Gyr Age Age
18- 23 F6.3 mag Mv Integrated absolute visual magnitude
26- 31 F6.3 mag Mbol Integrated absolute bolometric magnitude
34- 39 F6.3 mag BC Bolometric correction
42- 47 F6.3 mag U-B U-B integrated color
50- 55 F6.3 mag B-V B-V integrated color
58- 63 F6.3 mag V-R V-R integrated color
66- 71 F6.3 mag R-I R-I integrated color
74- 79 F6.3 mag V-J V-J integrated color
82- 87 F6.3 mag V-K V-K integrated color
90- 95 F6.3 mag V-L V-L integrated color
98-103 F6.3 mag V-M V-M integrated color
106-111 F6.3 mag V-N V-N integrated color
114-119 F6.3 mag 1550-V 1550-V integrated color defined as in
Burstein et al. 1988
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Reference:
Burstein D. et al. 1988, ApJ 328, 440 =1988ApJ...328..440B 1988ApJ...328..440B
(End) Patricia Bauer [CDS] 04-Apr-1996