We have analyzed the distribution of early-type galaxies (ETGs) in the effective surface intensity vs. effective radius (Ie − Re) plane and in the total luminosity vs. central stellar velocity dispersion (L − σ) diagram, with the aim of studying the physical variables that allow the transformation of one space-parameter into the other. We find that the classical Faber–Jackson relation L = L0 σα, in which the parameters L0 and α are confined in a small range of possible values, is incompatible with the distribution observed in the Ie − Re plane. The two distributions become mutually consistent only if luminosity is not considered a pure proxy of mass but a variable tightly dependent on the past history of mass assembling and star formation and on the present evolutionary state of the stellar content of a galaxy. The solution comes by considering the L = L0′ σβ law proposed by D’Onofrio et al. in 2020, in which both L0′ and β can vary considerably from galaxy to galaxy. We will also show that the data of the Illustris numerical simulation prove the physical foundation of the L = L0′ σβ law and confirm the prediction of the Zone of Exclusion (ZoE) originating from the intersection of the virial law with the L = L0′ σβ relation. The ZoE is the region in the Ie − Re and Re − Ms diagrams avoided by real galaxies, and the border of which marks the condition of ‘full’ virial equilibrium with no recent significant merger events and no undergoing star formation.

Tomography of the Ie-Re and L-sigma planes

D'Onofrio M.
;
Chiosi C.
2022

Abstract

We have analyzed the distribution of early-type galaxies (ETGs) in the effective surface intensity vs. effective radius (Ie − Re) plane and in the total luminosity vs. central stellar velocity dispersion (L − σ) diagram, with the aim of studying the physical variables that allow the transformation of one space-parameter into the other. We find that the classical Faber–Jackson relation L = L0 σα, in which the parameters L0 and α are confined in a small range of possible values, is incompatible with the distribution observed in the Ie − Re plane. The two distributions become mutually consistent only if luminosity is not considered a pure proxy of mass but a variable tightly dependent on the past history of mass assembling and star formation and on the present evolutionary state of the stellar content of a galaxy. The solution comes by considering the L = L0′ σβ law proposed by D’Onofrio et al. in 2020, in which both L0′ and β can vary considerably from galaxy to galaxy. We will also show that the data of the Illustris numerical simulation prove the physical foundation of the L = L0′ σβ law and confirm the prediction of the Zone of Exclusion (ZoE) originating from the intersection of the virial law with the L = L0′ σβ relation. The ZoE is the region in the Ie − Re and Re − Ms diagrams avoided by real galaxies, and the border of which marks the condition of ‘full’ virial equilibrium with no recent significant merger events and no undergoing star formation.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/3415076
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