Evolution of central galaxies in massive halos
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Data
2024-02-09Primeiro coorientador
Carvalho, Reinaldo Ramos de
Primeiro membro da banca
Ferreras, Ignacio
Segundo membro da banca
Gonçalves, Thiago Signorini
Terceiro membro da banca
Riffel, Rogemar Andre
Quarto membro da banca
Schimoia, Jáderson da Silva
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Mostrar registro completoResumo
Central galaxies of spheroidal morphology experience specific evolutionary processes due to
their privileged location in the center of massive dark matter halos. This is reflected in differences
between their physical properties and those of non-central spheroidal galaxies of comparable
stellar mass. Such processes, however, are not well understood, in particular regarding
their impact on the development of the baryonic content of central galaxies. Understanding
how centrals evolve will help to understand the physical mechanisms that dominate the core
region of clusters. For this purpose, we investigate the stellar populations and the interstellar
medium (ISM) in 15,107 elliptical central galaxies from the Spheroids Panchromatic Investigation
in Different Environmental Region (SPIDER) survey by using optical spectra from the
Sloan Digital Sky Survey (SDSS) - Data Release 12. We investigate the stellar age (Age) and
metallicity (Z) of our sample of centrals, using a stellar population synthesis code and also estimate
the [α/Fe] abundance ratio to constrain their star formation history. Visual extinction
(AV) and equivalent width of Hα (EWHα) are measured to characterize the properties of the
ionized gas. In order to obtain information about radio-loud nuclear activity on central galaxies
we investigate the radio luminosity (LR) using radio photometric data from the Very Large
Array Faint Images of the Radio Sky at Twenty-cm (VLA FIRST) survey. The main goal is
to analyze systematic differences between these properties as a function of halo mass (Mhalo)
and velocity dispersion (σ) for isolated centrals (ICs) and group centrals (GCs). Our results
reveals that the stellar populations and gas properties of ICs and GCs are primarily influenced
by σ, with Mhalo playing a secondary role. Higher σ values correlate with older, more metalrich
stellar populations and shorter star formation timescales in both ICs and GCs. At fixed σ
values, younger ages are observed at higher Mhalo values regardless of the environment. For
AV and EWHα, both parameters decrease with increasing σ and increase with Mhalo in ICs.
We also explore the ionization sources of warm gas and propose that ionized gas properties
result from a confrontation between intracluster medium (ICM) cooling and Active Galactic
Nuclei (AGN) feedback, assuming a Bondi accretion regime. In ICs, our model successfully
reproduces observed EWHα values. By including radio emission data in our analysis, we find
a trend between radio and optical emissions originated by nuclear activity. Using the LR as an
indicator of AGN kinetic power instead of the Bondi scenario in our model, we successfully
reproduce Hα emission in the case of ICs more accurately. However, this model fails to adequately
describe EWHα values in GCs. Overall, we observe inherent differences between ICs
and GCs, suggesting that the ratio between AGN kinetic power and ICM thermal energy influences
EWHα in ICs. Meanwhile, gas deposition in GCs appears to involve a more complex
interplay beyond a singular AGN–ICM interaction.
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