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Gravitational waveform predictions from 3D simulations of explosions of non-rotating massive stars with no magnetic fields have been extensively studied. However, the impact of magnetic fields and rotation on the core-collapse supernova gravitational-wave signal is not well understood beyond the core-bounce phase. Therefore, we perform four magnetohydrodynamical simulations of the explosion of a |$15\, {\rm M}_{\odot }$| star with the SFHx and SFHo equations of state. All of the models start with a weak magnetic field strength of |$10^{8}$|  G, and two of the models are rapidly rotating. We discuss the impact of the rotation and magnetic fields on the gravitational-wave signals. We find that the weak pre-collapse fields do not have a significant impact on the gravitational-wave signal amplitude. With rapid rotation, the f/g-mode trajectory can change in shape, and the dominant emission band becomes broader. We include the low-frequency memory component of the gravitational-wave signal from both matter motions and neutrino emission anisotropy. We show that including the gravitational waves from anisotropic neutrino emission increases the supernova gravitational-wave detection distances for the Einstein Telescope. The gravitational waves from anisotropic neutrino emission would also be detectable out to Mpc distances by a moon-based gravitational-wave detector. [ABSTRACT FROM AUTHOR]

We perform three-dimensional simulations of magnetorotational supernovae using a |$39\, {\rm M}_{\odot }$| progenitor star with two different initial magnetic field strengths of 1010  and 1012 G in the core. Both models rapidly undergo shock revival, and their explosion energies asymptote within a few hundred milliseconds to values of ≳2 × 1051 erg after conservatively correcting for the binding energy of the envelope. Magnetically collimated, non-relativistic jets form in both models, though the jets are subject to non-axisymmetric instabilities. The jets do not appear crucial for driving the explosion, as they only emerge once the shock has already expanded considerably. Our simulations predict moderate neutron star kicks of about 150 km s−1, no spin-kick alignment, and rapid early spin-down that would result in birth periods of about 20 ms, too slow to power an energetic gamma-ray burst jet. More than |$0.2\, {\rm M}_\odot$| of iron-group material is ejected, but we estimate that the mass of ejected 56Ni will be considerably smaller as the bulk of this material is neutron-rich. Explosive burning does not contribute appreciable amounts of 56Ni because the burned material originates from the slightly neutron-rich silicon shell. The iron-group ejecta also showed no pronounced bipolar geometry by the end of the simulations. The models thus do not immediately fit the characteristics of observed hypernovae, but may be representative of other transients with moderately high explosion energies. The gravitational-wave emission reaches high frequencies of up to 2000 Hz and amplitudes of over 100 cm. The gravitational-wave emission is detectable out to distances of ∼4 Mpc in the planned Cosmic Explorer detector. [ABSTRACT FROM AUTHOR]

We investigate the impact of rotation and magnetic fields on the dynamics and gravitational wave emission in 2D core–collapse supernova simulations with neutrino transport. We simulate 17 different models of |$15\, {\rm M}_\odot$| and |$39\, {\rm M}_\odot$| progenitor stars with various initial rotation profiles and initial magnetic fields strengths up to |$10^{12}\, \mathrm{G}$|⁠ , assuming a dipolar field geometry in the progenitor. Strong magnetic fields generally prove conducive to shock revival, though this trend is not without exceptions. The impact of rotation on the post-bounce dynamics is more variegated, in line with previous studies. A significant impact on the time-frequency structure of the gravitational wave signal is found only for rapid rotation or strong initial fields. For rapid rotation, the angular momentum gradient at the proto-neutron star surface can appreciably affect the frequency of the dominant mode, so that known analytic relations for the high-frequency emission band no longer hold. In case of two magnetorotational explosion models, the deviation from these analytic relations is even more pronounced. One of the magnetorotational explosions has been evolved to more than half a second after the onset of the explosion and shows a subsidence of high-frequency emission at late times. Its most conspicuous gravitational wave signature is a high-amplitude tail signal. We also estimate the maximum detection distances for our waveforms. The magnetorotational models do not stick out for higher detectability during the post-bounce and explosion phase. [ABSTRACT FROM AUTHOR]

We present 3D core-collapse supernova simulations of massive Population III progenitor stars at the transition to the pulsational pair instability regime. We simulate two progenitor models with initial masses of |$85$| and |$100\, \mathrm{M}_\odot$| with the LS220, SFHo, and SFHx equations of state. The |$85\, \mathrm{M}_{\odot }$| progenitor experiences a pair instability pulse coincident with core collapse, whereas the |$100\, \mathrm{M}_{\odot }$| progenitor has already gone through a sequence of four pulses |$1500$| yr before collapse in which it ejected its H and He envelope. The |$85\, \mathrm{M}_{\odot }$| models experience shock revival and then delayed collapse to a black hole (BH) due to ongoing accretion within hundreds of milliseconds. The diagnostic energy of the incipient explosion reaches up to |$2.7\times 10^{51}\, \mathrm{erg}$| in the SFHx model. Due to the high binding energy of the metal core, BH collapse by fallback is eventually unavoidable, but partial mass ejection may be possible. The |$100\, \mathrm{M}_\odot$| models have not achieved shock revival or undergone BH collapse by the end of the simulation. All models exhibit relatively strong gravitational-wave emission both in the high-frequency g-mode emission band and at low frequencies. The SFHx and SFHo models show clear emission from the standing accretion shock instability. For our models, we estimate maximum detection distances of up to |$\mathord {\sim }46\, \mathrm{kpc}$| with LIGO and |$\mathord {\sim } 850\, \mathrm{kpc}$| with Cosmic Explorer. [ABSTRACT FROM AUTHOR]

We present 3D simulations of the core-collapse of massive rotating and non-rotating progenitors performed with the general relativistic neutrino hydrodynamics code coconut-fmt. The progenitor models include Wolf-Rayet stars with initial helium star masses of |$39\, \mathrm{ M}_{\odot }$| and |$20\, \mathrm{ M}_{\odot }$|⁠ , and an |$18\, \mathrm{ M}_{\odot }$| red supergiant. The |$39\, \mathrm{ M}_{\odot }$| model is a rapid rotator, whereas the two other progenitors are non-rotating. Both Wolf-Rayet models produce healthy neutrino-driven explosions, whereas the red supergiant model fails to explode. By the end of the simulations, the explosion energies have already reached |$1.1\times 10^{51}\, $| and |$0.6\times 10^{51}\, \mathrm{erg}$| for the |$39\, \mathrm{ M}_{\odot }$| and |$20\, \mathrm{ M}_{\odot }$| model, respectively. They produce neutron stars of relatively high mass, but with modest kicks. Due to the alignment of the bipolar explosion geometry with the rotation axis, there is a relatively small misalignment of 30° between the spin and the kick in the rapidly rotating |$39\, \mathrm{ M}_{\odot }$| model. For this model, we find that rotation significantly changes the dependence of the characteristic gravitational-wave frequency of the f-mode on the proto-neutron star parameters compared to the non-rotating case. Its gravitational-wave amplitudes would make it detectable out to almost 2 Mpc by the Einstein Telescope. The other two progenitors have considerably smaller detection distances, despite significant low-frequency emission in the most sensitive frequency band of current gravitational-wave detectors. [ABSTRACT FROM AUTHOR]

The mass and spin distributions of compact binary gravitational-wave sources are currently uncertain due to complicated astrophysics involved in their formation. Multiple sub-populations of compact binaries representing different evolutionary scenarios may be present amongst sources detected by Advanced LIGO and Advanced Virgo. In addition to hierarchical modelling, unmodelled methods can aid in determining the number of sub-populations and their properties. In this paper, we apply Gaussian mixture model clustering to 1000 simulated gravitational-wave compact binary sources from a mixture of five sub-populations. Using both mass and spin as input parameters, we determine how many binary detections are needed to accurately determine the number of sub-populations and their mass and spin distributions. In the most difficult case that we consider, where two sub-populations have identical mass distributions but differ in their spin, which is poorly constrained by gravitational-wave detections, we find that ∼400 detections are needed before we can identify the correct number of sub-populations. [ABSTRACT FROM AUTHOR]

We present a suite of seven 3D supernova simulations of non-rotating low-mass progenitors using multigroup neutrino transport. Our simulations cover single star progenitors with zero-age main-sequence masses between |$9.6$| and |$12.5 \, \mathrm{M}_\odot$| and (ultra)stripped-envelope progenitors with initial helium core masses between |$2.8$| and |$3.5 \, \mathrm{M}_\odot$|⁠. We find explosion energies between |$0.1$| and |$0.4\, \mathrm{Bethe}$|⁠, which are still rising by the end of the simulations. Although less energetic than typical events, our models are compatible with observations of less energetic explosions of low-mass progenitors. In six of our models, the mass outflow rate already exceeds the accretion rate on to the proto-neutron star, and the mass and angular momentum of the compact remnant have closely approached their final value, barring the possibility of later fallback. While the proto-neutron star is still accelerated by the gravitational tug of the asymmetric ejecta, the acceleration can be extrapolated to obtain estimates for the final kick velocity. We obtain gravitational neutron star masses between |$1.22$| and |$1.44 \, \mathrm{M}_\odot$|⁠, kick velocities between |$11$| and |$695\, \mathrm{km}\, \mathrm{s}^{-1}$|⁠, and spin periods from |$20\, \mathrm{ms}$| to |$2.7\, \mathrm{s}$|⁠, which suggest that typical neutron star birth properties can be naturally obtained in the neutrino-driven paradigm. We find a loose correlation between the explosion energy and the kick velocity. There is no indication of spin–kick alignment, but a correlation between the kick velocity and the neutron star angular momentum, which needs to be investigated further as a potential point of tension between models and observations. [ABSTRACT FROM AUTHOR]