Explore the vast range of titles available.

At the end of a massive star's life, a violent explosion known as a supernova occurs and releases 99% of the star's gravitational binding energy in the form of neutrinos. Although the explosion generates a huge burst of neutrinos, the large distance to earthbound detectors, low cross sections, and flavour changing oscillations can make detection and analysis challenging. Only one neutrino burst from a supernova has ever been detected, but neutrino detectors have been waiting patiently for another. The SNO+ detector at SNOLAB can be used as a supernova detector during both regular operation and calibrations by measuring the burst of neutrinos from a supernova. We present the neutrino detection method and analysis of potential galactic supernova with the SNO+ detector.

Today we have a solid, if incomplete, physical picture of how inertia is created in the standard model. We know that most of the visible baryonic ‘mass’ in the Universe is due to gluonic back-reaction on accelerated quarks, the latter of which attribute their own inertia to a coupling with the Higgs field – a process that elegantly and self-consistently also assigns inertia to several other particles. But we have never had a physically viable explanation for the origin of rest-mass energy, in spite of many attempts at understanding it towards the end of the nineteenth century, culminating with Einstein’s own landmark contribution in his Annus Mirabilis. Here, we introduce to this discussion some of the insights we have garnered from the latest cosmological observations and theoretical modeling to calculate our gravitational binding energy with that portion of the Universe to which we are causally connected, and demonstrate that this energy is indeed equal to m c 2 when the inertia m is viewed as a surrogate for gravitational mass.

The results of the investigation of the core-envelope model presented in Negi et al. (Gen. Relativ. Gravit. 22:735, 1990 ) have been discussed in view of the reference (Negi et al. in Gen. Relativ. Gravit. 51:131, 2019 ). It is seen that there are significant changes in the results to be addressed. In addition, I have also calculated the gravitational binding energy, causality and pulsational stability of the structures which were not considered in Negi et al. (Gen. Relativ. Gravit. 22:735, 1990 ). The modified results have important consequences to model neutron stars and pulsars. The maximum neutron star mass obtained in this study corresponds to the mean value of the classical results obtained by Rhoades and Ruffini (Phys. Rev. Lett. 32:324, 1974 ) and the upper bound on neutron star mass obtained by Kalogera and Baym (Astrophys. J. 470:L61, 1996 ) and is much closer to the most recent theoretical estimate made by Sotani (Phys. Rev. C 95:025802, 2017 ). On one hand, when there are only few equations of state (EOSs) available in the literature which can fulfil the recent observational constraint imposed by the largest neutron star masses around 2 M ⊙ (Demorest et al. in Nature 467:1081, 2010 ; Antoniadis et al. in Science 340:6131, 2013 ; Cromartie et al. in Nat. Astron. 4:72, 2020 ), the present analytic models, on the other hand, can comfortably satisfy this constraint. Furthermore, the maximum allowed value of compactness parameter u ( ≡ M / a ; mass to size ratio in geometrized units) ≤ 0.30 obtained in this study is also consistent with an absolute maximum value of u max = 0.333 − 0.005 + 0.001 resulting from the observation of binary neutron stars merger GW170817 (see, e.g. Koliogiannis and Moustakidis in Astrophys. Space Sci. 364:52, 2019 ).

Core-collapse supernova explosions are driven by a central engine that converts a small fraction of the gravitational binding energy released during core collapse to outgoing kinetic energy. The suspected mode for this energy conversion is the neutrino mechanism, where a fraction of the neutrinos emitted from the newly formed protoneutron star are absorbed by and heat the matter behind the supernova shock. Accurate neutrino-matter interaction terms are crucial for simulating these explosions. In this proceedings for IAUS 331, SN 1987A, 30 years later, we explore several corrections to the neutrino-nucleon scattering opacity and demonstrate the effect on the dynamics of the core-collapse supernova central engine via two dimensional neutrino-radiation-hydrodynamics simulations. Our results reveal that the explosion properties are sensitive to corrections to the neutral-current scattering cross section at the 10-20% level, but only for densities at or above ~1012 g cm−3.

When a massive star collapses at the end of its life, nearly all of the gravitational binding energy of the resulting remnant is released in the form of neutrinos. The burst of neutrinos from a Galactic core collapse supernova will be detected in neutrino detectors worldwide. This talk will cover supernova neutrino detection techniques in general, current supernova neutrino detectors, and prospects for specific future experiments.

A thorough understanding of properties of neutron stars requires both a reliable knowledge of the equation of state (EOS) of super-dense nuclear matter and the strong-field gravity theories simultaneously. To provide information that may help break this EOS-gravity degeneracy, we investigate effects of nuclear symmetry energy on the gravitational binding energy of neutron stars within GR and the scalar-tensor subset of alternative gravity models. We focus on effects of the slope L of nuclear symmetry energy at saturation density and the high-density behavior of nuclear symmetry energy. We find that the variation of either the density slope L or the high-density behavior of nuclear symmetry energy leads to large changes in the binding energy of neutron stars. The difference in predictions using the GR and the scalar-tensor theory appears only for massive neutron stars, and even then is significantly smaller than the difference resulting from variations in the symmetry energy.

When a massive star collapses at the end of its life, nearly all of the gravitational binding energy of the resulting remnant is released in the form of neutrinos. The burst of neutrinos from a Galactic core collapse supernova will be detected in neutrino detectors worldwide. This talk will cover supernova neutrino detection techniques in general, current supernova neutrino detectors, and prospects for specific future experiments.

Our concept of mass has evolved considerably over the centuries, most notably from Newton to Einstein, and then even more vigorously with the establishment of the standard model and the subsequent discovery of the Higgs boson. Mass is now invoked in various guises depending on the circumstance: it is used to represent inertia, or as a coupling constant in Newton's law of universal gravitation, and even as a repository of a mysterious form of energy associated with a particle at rest. But recent developments in cosmology have demonstrated that rest-mass energy is most likely the gravitational binding energy of a particle in causal contact with that portion of the Universe within our gravitational horizon. In this paper, we examine how all these variations on the concept of mass are actually interrelated via this new development and the recognition that the source of gravity in general relativity is ultimately the total energy in the system.

The low mean densities of sub-Neptunes imply that they formed within a few million years and accreted primordial envelopes. Because these planets receive a total X-ray and extreme ultra-violet flux that is comparable to the gravitational binding energy of their envelopes, their primordial hydrogen-helium atmospheres are susceptible to mass loss. Models of photoevaporating sub-Neptunes have so far assumed that envelope compositions remain constant over time. However, preferential loss of atmospheric hydrogen has the potential to change their compositions. Here, by modeling the thermal and compositional evolution of sub-Neptunes undergoing atmospheric escape with diffusive separation between hydrogen and helium, we show that planets with radii between 1.6 and 2.5 that of Earth can become helium-enhanced from billions of years of photoevaporation, obtaining helium mass fractions in excess of 40%. Atmospheric helium enhancement can be detected through transmission spectra, providing a novel observational test for whether atmospheric escape creates the radius valley.

In 2019, Neutron star Interior Composition ExploreR (NICER) mission released its findings on the mass and radius of the isolated neutron star (INS) PSR J0030+0451, revealing a mass of approximately 1.4 solar masses (\\(M_{\\odot}\\)) and a radius near 13 kilometers. However, the recent re-analysis by the NICER collaboration \\citep{vinciguerra2024updated} suggests that the available data primarily yields a precise inference of the compactness for this source while the resulting mass and radius are strongly model-dependent and diverse (the 68.3\\% credible regions just overlap slightly for the ST+PDT and PDT-U models). By integrating this compactness data with the equation of state (EoS) refined by our latest investigations, we have deduced the mass and radius for PSR J0030+0451, delivering estimates of \\(M=1.48^{+0.09}_{-0.10}~M_\\odot\\) and \\(R=12.38_{-0.70}^{+0.51}~{\\rm km}\\) for the compactness found in ST+PDT model, alongside \\(M=1.47^{+0.14}_{-0.20}~M_\\odot\\) and \\(R=12.37_{-0.69}^{+0.50}~{\\rm km}\\) for the compactness in PDT-U model. These two groups of results are well consistent with each other and the direct X-ray data inference within the ST+PDT model seems to be favored. Additionally, we have calculated the tidal deformability, moment of inertia, and gravitational binding energy for this NS. Furthermore, employing these refined EoS models, we have updated mass-radius estimates for three INSs with established gravitational redshifts.