Journal Club


"The nature of the Milky Way's halo revealed by the three integrals of motion"

André Rodrigo da Silva (CAMK, Warsaw)

Based on a new selection method of halo stars in the Milky Way local volume, the general chemo-dynamical structure of the stellar halo is explored. The method relies on the phase-space distribution defined by the three integrals of motion in an axisymmetric Galactic potential. The talk is based on: "The nature of the Milky Way's halo revealed by the three integrals of motion" by Carollo, Daniela and Chiba, Masashi, e-print: arXiv:2010.00235


"Neutron stars and scalar-tensor theories"

Jacopo Soldateschi (INAF Osservatorio di Arcetri, Florence)

Among the most promising “alternative theories of gravity”, one of the most studied class is that of the “scalar-tensor theories” (STTs), because they are the most simple extensions of general relativity (GR), they don’t lead to pathologies in the spacetime properties, and show behaviours that look promising in the context of cosmological constraints. Some of these theories predict a phenomenon known as “spontaneous scalarisation”, which produces strong deviations from GR in compact objects (like NSs) while fulfilling the strong observational constraints in the weak gravity regime. Such phenomenon is potentially observable in this new era of gravitational waves (GWs) astronomy. I will present the results we obtained in the scenario of numerical multi-dimensional modelling of NSs in STTs, for the first time with the inclusion of magnetic fields, accomplished by the simultaneous solution of the coupled Scalar-Einstein-Maxwell equations. Our aim is to understand how global quantities (like the mass and the magnetic deformation), that are potentially observable, deviate from GR, in the hope of providing new tools to test these theories through future observations. Moreover, I will explain how these deviations translate to the emission of GWs. Finally, I will present the formalism of our algorithm, showing how it can be extended to include, in particular, realistic equations of state.