About – Master Project MAC

The goal of this project …

The goal of this project is to provide quantitative predictions of the key parameters that govern the emission of measurable signals from compact objects, based on the uncertainties associated with subjective microphysics.

Credit: B.P.Abbott et al. PRL 119, 161101 (2017)

Three different phenomenologies will be studied

The emission of GW from neutron star binaries and associated parameters (tidal polarizability, r-modes). In this case the dominant uncertainties are due to the EoS modeling, and the possible phase transitions of the dense matter.

The dynamics of CCSN collapse and the estimation of the emitted neutrino spectrum, with a unified treatment of the EoS and the distribution of nuclei at thermodynamic equilibrium. The sources of uncertainty then lie in the nuclear mass model and in the EC rates.

The cooling of neutron stars and the crystallization of the crust. For these phenomena the uncertainties in the modeling derive both from the EoS (for isolated or non-isolated stars) and from the surface properties of very neutron-rich nuclei.

Method / Development plan

The main ingredients of nuclear physics that enter into the modeling are the energy function of homogeneous matter, EC levels, neutrino transport and the masses of very neutron-rich nuclei. Over the 36-month duration of the project we expect : (i) develop an empirical description of these four aspects, explicitly constrained on microscopic calculations of the DFT and chiral EFT type, and (ii) study their influence on the different astrophysical phenomena. During the previous MAC project we developed a meta-modeling of homogeneous and inhomogeneous matter, as well as a perturbing method for the evaluation of the nuclear distribution. We will now extinguish these theoretical tools to include different relativistic effects, the possibility of high density phase transitions, the explicit temperature dependence of the functional, and the phenomenon of crystallization at low temperature. The surface properties of neutron-rich nuclei will be studied with ETF and HFB data-constrained techniques. As far as nuclear data are concerned, sensitivity studies and mass measurements performed with MAC have allowed us to identify the key nuclei and observables involved in the collapse and we now propose to establish the most relevant experimental measurements to be proposed to better constrain them.

Expected results

The relativistic extension of meta-modeling and the introduction of possible phase transitions in dense matter will allow to complete our evaluation of the most important empirical parameters that limit theoretical predictions on the masses and radii of neutron stars, as well as on tidal polarisability.
The finite temperature extension of the functional will allow, in direct collaboration with the VIRGO collaboration, to produce waveforms with controlled uncertainties not only for the GW signal coming from the fusion of NS (“inspiral”), but also for the post-merger signal that will be detectable with the new generation of gravitational interferometers (ET).
A collaboration with the University of Milano will allow to translate our Bayesian estimate of the moment of inertia of the crust with controlled uncertainties, into a quantitative constraint on the mass of the pulsars, based on the amplitude and frequency of the observed “glitch”.
We will compute for the first time, in collaboration with the University of Brussels, the evolution of the crystallization temperature of neutron stars with microscopic functionals and taking into account the complete distribution of nuclear species at finite temperature, in a thermodynamically coherent approach. This same project will allow us to estimate for the first time with a microscopic and quantum approach the impurity coefficient that enters in the modeling of the cooling of isolated NS.
We will work on experimental proposals aimed at constraining the electron capture rate of key nuclei around Ni78 that we have identified in sensitivity studies during the CCSN collapse phase.
In collaboration with the team from the University of Brussels and the Nicolaus Copernicus Astronomical Center (CAMK, Vasovia), EoS based on microscopic functionalities will be developed for accreting neutron stars. These new models will be used to study the microscopic and macroscopic properties of these neutron stars.

Participating labs

IN2P3

GANIL

IJCLAB

IP2I Lyon

LPC Caen

LUTH Meudon

Some working documents

TIDAL DEFORMATIONS OF NEUTRON STARS WITH ELASTIC CRUSTS

F. Gittins, N. Andersson and J. P. Pereira

GW190814: GRAVITATIONAL WAVES FROM THE COALESCENCE OF A 23 M BLACK HOLE WITH A 2.6 M COMPACT OBJECT

LIGO Scientific Collaboration and Virgo Collaboration

GW190814: GRAVITATIONAL WAVES FROM THE COALESCENCE OF A 23 SOLAR MASS BLACK HOLE WITH A 2.6 SOLAR MASS COMPACT OBJECT

The Astrophysical Journal Letters, 896:L44 (20pp), 2020 June 20