Three approaches for the classification of protoneutron star oscillation modes

RODRÍGUEZ, M.C.; IGNACIO FRANCISCO RANEA SANDOVAL; CECILIA CHIRENTI; DAVID RADICE

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2023

0035-8711

The future detection of gravitational waves (GWs) from a galactic core-collapse supernova will provide information on thephysics inside protoneutron stars (PNS). In this work, we apply three different classification methods for the PNS non-radialoscillation modes: Cowling classification, Generalized Cowling Nomenclature (GCN), and a Classification Based on ModalProperties (CBMP). Using PNS models from 3D simulations of core-collapse supernovae, we find that in the early stages of thePNS evolution, typically before 0?4 seconds after the bounce, the Cowling classification is inconsistent, but the GCN and theCBMP provide complementary information that helps to understand the evolution of the modes. In the GCN, we note severalavoided crossings as the mode frequencies evolve at early times, while the CBMP tracks the modes across the avoided crossings.We verify that the strongest emission of GWs by the PNS corresponds to the 𝑓 -mode in the GCN, indicating that the modetrapping region alternates between the core and the envelope at each avoided crossing. At later times, approximately 0?4 secondsafter the bounce, the three classification methods present a similar description of the mode spectrum. We use our results to testuniversal relations for the PNS modes according to their classification and find that the behaviour of the universal relations for𝑓 - and 𝑝-modes is remarkably simple in the CBMP.