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Stellar Populations in Local and high redshift Universe
12 Febbraio 2019 @ 11:45 - 12:45
Synthetic stellar libraries are quite popular to constrain the stellar pop-
ulations (age and metallicity distribution) of unresolved systems like high redshift galaxies.
However, they are typically based on theoretical Spectral Energy Distributions (SEDs).
It is important to build up empirical synthetic stellar li-
braries, calibrated on local systems and
covering a broad range in ages (globular clusters, old open clusters),
chemical compositions (iron, alpha, CNO) and dynamical properties (nearby
dwarf galaxies), able to improve our SED fitting codes to deeply investigate
high redshift galaxies.
To do that, I am taking advantages of a sample of 65 Galactic globular clus-
ters (GGCs) for which we have accurate and homogeneous optical photometry
based on space (ACS at HST, innermost regions) and ground-based
(up to the tadial radius).
In particular, I will present the results on the study of the Horizontal Branch
(HB) morphology for 64 GGCs in our sample.
I will introduce a very new photometric morphology index based
on the cumulative density function of the stars along the HB,
useful to investigate the well known “second
parameter problem” affecting age estimations and so, stellar libraries.
I will also discuss the results of the analysis on galaxy
evolution through the Galaxy Stellar Mass Function (GSMF) up to redf-
shift 4, obtained combining all the five CANDELS fields (GOODS-South,
GOODS-North, EGS, COSMOS, UDS), the Frontier Fields Parallels (Abell 2744,
MACSJ0416, MACSJ0717, MACSJ1149) and the Ultravista/COSMOS
field. Stellar masses have been estimated fitting the photometry to syn-
thetic models: these surveys are characterized by multi-wavelength (deep
optical/near-infrared/mid-infrared) coverage (CANDELS), very high limiting magnitudes
(Frontier Fields) and large areas (UltraVista), allowing to explore the GSMF
from low masses to the high-mass end.