TY  - JOUR
A1  - Emma, Mattia
A1  - Schianchi, Federico
A1  - Pannarale, Francesco
A1  - Sagun, Violetta
A1  - Dietrich, Tim
T1  - Numerical simulations of dark matter admixed neutron star binaries
JF  - Particles
N2  - Multi-messenger observations of compact binary mergers provide a new way to constrain the nature of dark matter that may accumulate in and around neutron stars. In this article, we extend the infrastructure of our numerical-relativity code BAM to enable the simulation of neutron stars that contain an additional mirror dark matter component. We perform single star tests to verify our code and the first binary neutron star simulations of this kind. We find that the presence of dark matter reduces the lifetime of the merger remnant and favors a prompt collapse to a black hole. Furthermore, we find differences in the merger time for systems with the same total mass and mass ratio, but different amounts of dark matter. Finally, we find that electromagnetic signals produced by the merger of binary neutron stars admixed with dark matter are very unlikely to be as bright as their dark matter-free counterparts. Given the increased sensitivity of multi-messenger facilities, our analysis gives a new perspective on how to probe the presence of dark matter.
KW  - numerical relativity
KW  - dark matter
KW  - neutron stars
KW  - equation of state;
KW  - gravitational-wave astronomy
KW  - multi-messenger astrophysics
Y1  - 2022
U6  - https://doi.org/10.3390/particles5030024
SN  - 2571-712X
VL  - 5
IS  - 3
SP  - 273
EP  - 286
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Gieg, Henrique
A1  - Schianchi, Federico
A1  - Dietrich, Tim
A1  - Ujevic, Maximiliano
T1  - Incorporating a Radiative Hydrodynamics Scheme in the Numerical-Relativity Code BAM
JF  - Universe : open access journal
N2  - To study binary neutron star systems and to interpret observational data such as gravitational-wave and kilonova signals, one needs an accurate description of the processes that take place during the final stages of the coalescence, for example, through numerical-relativity simulations. In this work, we present an updated version of the numerical-relativity code BAM in order to incorporate nuclear-theory-based equations of state and a simple description of neutrino interactions through a neutrino leakage scheme. Different test simulations, for stars undergoing a neutrino-induced gravitational collapse and for binary neutron stars systems, validate our new implementation. For the binary neutron stars systems, we show that we can evolve stably and accurately distinct microphysical models employing the different equations of state: SFHo, DD2, and the hyperonic BHB Lambda phi. Overall, our test simulations have good agreement with those reported in the literature.
KW  - numerical relativity
KW  - binary neutron stars
KW  - neutrinos
KW  - leakage scheme
Y1  - 2022
U6  - https://doi.org/10.3390/universe8070370
SN  - 2218-1997
VL  - 8
IS  - 7
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Nedora, Vsevolod
A1  - Radice, David
A1  - Bernuzzi, Sebastiano
A1  - Perego, Albino
A1  - Daszuta, Boris
A1  - Endrizzi, Andrea
A1  - Prakash, Aviral
A1  - Schianchi, Federico
T1  - Dynamical ejecta synchrotron emission as a possible contributor to the changing behaviour of GRB170817A afterglow
JF  - Monthly notices of the Royal Astronomical Society
N2  - Over the past 3 yr, the fading non-thermal emission from the GW170817 remained generally consistent with the afterglow powered by synchrotron radiation produced by the interaction of the structured jet with the ambient medium. Recent observations by Hajela et al. indicate the change in temporal and spectral behaviour in the X-ray band. We show that the new observations are compatible with the emergence of a new component due to non-thermal emission from the fast tail of the dynamical ejecta of ab-initio binary neutron star merger simulations. This provides a new avenue to constrain binary parameters. Specifically, we find that equal mass models with soft equations of state (EOSs) and high-mass ratio models with stiff EOSs are disfavoured as they typically predict afterglows that peak too early to explain the recent observations. Moderate stiffness and mass ratio models, instead, tend to be in good overall agreement with the data.
KW  - equation of state
KW  - gravitational waves
KW  - neutron star mergers
Y1  - 2021
U6  - https://doi.org/10.1093/mnras/stab2004
SN  - 0035-8711
SN  - 1365-2966
VL  - 506
IS  - 4
SP  - 5908
EP  - 5915
PB  - Oxford Univ. Press
CY  - Oxford
ER  -