Insights into formation scenarios of massive Early-Type galaxies from spatially resolved stellar population analysis in CALIFA. (arXiv:1906.02209v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Zibetti_S/0/1/0/all/0/1">Stefano Zibetti</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Gallazzi_A/0/1/0/all/0/1">Anna R. Gallazzi</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Hirschmann_M/0/1/0/all/0/1">Michaela Hirschmann</a> (2 and 3), <a href="http://arxiv.org/find/astro-ph/1/au:+Consolandi_G/0/1/0/all/0/1">Guido Consolandi</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Falcon_Barroso_J/0/1/0/all/0/1">Jesús Falcón-Barroso</a> (5 and 6), <a href="http://arxiv.org/find/astro-ph/1/au:+Ven_G/0/1/0/all/0/1">Glenn van de Ven</a> (7), <a href="http://arxiv.org/find/astro-ph/1/au:+Lyubenova_M/0/1/0/all/0/1">Mariya Lyubenova</a> (8) ((1) INAF-Osservatorio Astrofisico di Arcetri, (2) Institut d'Astrophysique de Paris, CNRS, Université Pierre & Marie Curie, (3) DARK, Niels Bohr Institute, University of Copenhagen, (4) INAF-Osservatorio Astronomico di Brera, (5) Instituto de Astrofísica de Canarias, (6) Departamento de Astrofísica, Universidad de La Laguna, (7) Department of Astrophysics, University of Vienna, (8) European Southern Observatory)
We perform spatially resolved stellar population analysis for a sample of 69
early-type galaxies (ETGs) from the CALIFA integral field spectroscopic survey,
including 48 ellipticals and 21 S0’s. We generate and quantitatively
characterize profiles of light-weighted mean stellar age and metallicity within
$lesssim 2text{R}_text{eff}$, as a function of radius and stellar-mass
surface density $mu_*$. We study in detail the dependence of profiles on
galaxies’ global properties, including velocity dispersion $sigma_e$, stellar
mass, morphology. ETGs are universally characterized by strong, negative
metallicity gradients ($sim -0.3,text{dex}$ per $text{R}_text{eff}$)
within $1,text{R}_text{eff}$, which flatten out moving towards larger radii.
A quasi-universal local $mu_*$-metallicity relation emerges, which displays a
residual systematic dependence on $sigma_e$, whereby higher $sigma_e$ implies
higher metallicity at fixed $mu_*$. Age profiles are typically U-shaped, with
minimum around $0.4,text{R}_text{eff}$, asymptotic increase to maximum ages
beyond $sim 1.5,text{R}_text{eff}$, and an increase towards the centre. The
depth of the minimum and the central increase anti-correlate with $sigma_e$.
We qualitatively interpret these observations in a two-phase scenario for the
formation of ETGs. The region within $1,text{R}_text{eff}$ mainly results
from the competing effects of dissipative collapse, by which star formation
proceeds outside-in and the negative metallicity gradient is established, and
of AGN feedback, resulting in an inside-out quenching that is more effective
for larger $sigma_e$ (due to the black-hole mass vs. $sigma$ relation). The
flatter stellar population profiles in the outer regions likely result from the
increasing contribution of accreted satellites, that are quenched and
low-metallicity.
We perform spatially resolved stellar population analysis for a sample of 69
early-type galaxies (ETGs) from the CALIFA integral field spectroscopic survey,
including 48 ellipticals and 21 S0’s. We generate and quantitatively
characterize profiles of light-weighted mean stellar age and metallicity within
$lesssim 2text{R}_text{eff}$, as a function of radius and stellar-mass
surface density $mu_*$. We study in detail the dependence of profiles on
galaxies’ global properties, including velocity dispersion $sigma_e$, stellar
mass, morphology. ETGs are universally characterized by strong, negative
metallicity gradients ($sim -0.3,text{dex}$ per $text{R}_text{eff}$)
within $1,text{R}_text{eff}$, which flatten out moving towards larger radii.
A quasi-universal local $mu_*$-metallicity relation emerges, which displays a
residual systematic dependence on $sigma_e$, whereby higher $sigma_e$ implies
higher metallicity at fixed $mu_*$. Age profiles are typically U-shaped, with
minimum around $0.4,text{R}_text{eff}$, asymptotic increase to maximum ages
beyond $sim 1.5,text{R}_text{eff}$, and an increase towards the centre. The
depth of the minimum and the central increase anti-correlate with $sigma_e$.
We qualitatively interpret these observations in a two-phase scenario for the
formation of ETGs. The region within $1,text{R}_text{eff}$ mainly results
from the competing effects of dissipative collapse, by which star formation
proceeds outside-in and the negative metallicity gradient is established, and
of AGN feedback, resulting in an inside-out quenching that is more effective
for larger $sigma_e$ (due to the black-hole mass vs. $sigma$ relation). The
flatter stellar population profiles in the outer regions likely result from the
increasing contribution of accreted satellites, that are quenched and
low-metallicity.
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