Stellar processes driven by the rise of nuclear collectivity

Abstract The sudden rise of nuclear collectivity above the pairing gap is revealed in this work as the primary source for the relative increase of the symmetry energy with respect to the ground state, as originally suggested by Donati and collaborators. This finding is uncovered by available data on giant dipole resonances built on excited states and 1 $$\hbar \omega $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>ħ</mml:mi> <mml:mi>ω</mml:mi> </mml:mrow> </mml:math> shell-model calculations of the myriads of products of electric dipole matrix elements that compose the nuclear dipole polarizability of the ground and first-excited states. At the temperatures involved in stellar environments, a larger symmetry energy impacts stellar collapse, the nucleosynthesis of heavy elements and the nuclear equation of state of hot neutron stars.