Recent advancements in core-collapse supernova modeling are revealing a new black hole (BH) formation channel in which a BH forms within about a second of shock revival yet still results in a successful supernova. The limited body of literature on these black hole supernovae (BHSNe) has mostly focused on highly massive, compact progenitors. I will present a sample of ~40 stars between 19 and...
Gravitational wave approximants are widely used in the analysis of Gravitational wave signals. They are highly accurate but they still lack speed. We present an autoencoder based surrogate model for BBH gravitational wave signals. We train our autoencoder on a NR informed surrogate model, we modify it so it can produce waveforms from the initial binary system parameters and then we fine tune...
The magnetorotational instability (MRI) is considered a leading mechanism for driving angular momentum transport in differentially rotating astrophysical flows, including accretion disks and protoneutron stars. This process is mediated by the exponential amplification of the magnetic field whose final amplitude is envisioned to be limited by secondary (parasitic) instabilities. By relaxing...
The dynamical stability of differentially rotating neutron stars, including hypermassive neutron stars, is of paramount importance in understanding the fate of the postmerger remnant of binary neutron stars mergers and the formation of a black hole during core-collapse supernovae. We study systematically the dynamical stability of differentially rotating neutron stars within a broad range of...
In this talk we discuss a fully 3D numerical evolution code to study neutron stars within the framework of massive-scalar-tensor (MST) theories. Our focus is to study the gravitational collapse of rapidly rotating neutron stars by exploring the parameter space defined by the scalar field couplings and the mass. We investigate how these parameters influence both the dynamical characteristics of...
Gravitational waves (GWs) from binary neutron star (BNS) mergers offer crucial insights into the Neutron Star (NS) interiors and nuclear physics. The inference of NS properties hinges on the GW waveform, and achieving an accurate description of BNS GWs is a key focus of current research. The leading tidal contribution arises from the f-mode oscillation of the NS, for which the mode frequency...
We investigate the non-radial gravity-pulsation discontinuity mode (g-mode) in neutron stars with a strong 1st-order phase transition, dubbed twin stars. For this, we consider the standard four categories and employ the constant-speed-of-sound parametrization which accounts for the QCD transition. We find that depending on the category, the relations between g-mode frequencies and...
The gravitational radiation from core-collapse supernovae (CCSNe) is dominated by the oscillation modes of the proto-neutron star associated and the stalled accretion shock, and can be detectable in the case of galactic distances. These modes have been computed by several methods [1, 2, 3]. In this talk, we present the first steps of a potential alternative method to classify the different...
Numerical simulation of strange quark stars is challenging due to the strong density discontinuity at the stellar surface. In this talk, we shall present our successful simulations of rapidly rotating quark stars and study their oscillation modes in full general relativity.
We present new simulations performed with Spritz, a general-relativistic magnetohydrodynamics (GRMHD) code designed for high-precision studies of binary neutron star (BNS) mergers with realistic nuclear equations of state (EOS). We evolve both magnetized and non-magnetized equal-mass binaries, employing two tabulated EOS modeled after the GW170817 event. Our analysis focuses on the...
We investigate the impact of a hypothetical bosonic dark matter (DM) candidate, the sexaquark, on the fundamental (f-mode) oscillations of neutron stars (NSs). By varying the DM particle mass and considering different core compositions including hypernuclear matter, sexaquark DM, and deconfined quark matter (QM), we construct hybrid equations of state (EOS) with a smooth hadron-quark crossover...
