Teorico

Gravitational phase transitions in accreting neutron stars

by Arthur Suvorov (University of Tübingen)

Europe/Rome
Aula Conversi (Dip. di Fisica - Edificio G. Marconi)

Aula Conversi

Dip. di Fisica - Edificio G. Marconi

Description

Many scalar-tensor theories predict that tachyonic instabilities can operate at the extreme energy densities found inside neutron stars, enabling a `scalarised' branch of hydrostatic equilibria. Objects within this branch resemble the so-called mass twins in general relativity that appear for equations of state containing first-order phase transitions. The maximum mass of scalarised stars can be lower than Einstein ones if the scalar charge "strengthens" gravity. I will present some numerical simulations in a few select scalar-tensor theories where a scalarized star near the mass limit accretes material, shoots over the allowed maximum of the branch, and migrates towards a GR solution in what we call a gravitational phase transition. The scalar field is radiated away, though in the aftermath we are left with a stable neutron star rather than a black hole. The astrophysical implications of such hypothetical events and their detection prospects will be described in detail, highlighting again the duality found when strong gravity and supranuclear matter coexist.

Organised by

Paolo Pani