Strangeness and Metastable Neutron Stars: What Might have Happened to SN1987A

It is generally agreed on that the tremendous densities reached in the centers of neutron stars provide a high-pressure environment in which numerous novel particles processes are likely to compete with each other. These processes range from the generation of hyperons to quark deconfinement to the formation of kaon condensates and H-matter. There are theoretical suggestions of even more exotic processes inside neutron stars, such as the formation of absolutely stable strange ...

It is generally agreed on that the tremendous densities reached in the centers of neutron stars provide a high-pressure environment in which several intriguing particles processes may compete with each other. These range from the generation of hyperons to quark deconfinement to the formation of kaon condensates and H-matter. There are theoretical suggestions of even more exotic processes inside neutron stars, such as the formation of absolutely stable strange quark matter. In...

We investigate the role of hyperons in the dynamical collapse of a non-rotating massive star to a black hole(BH) using one dimensional general relativistic $GR1D$ code. We follow the dynamical formation and evolution of a protoneutron star (PNS) to a black hole using various progenitor models, adopting a hyperonic equation of state (EoS) generated by Shen et. al. We compare the results with those of nuclear EoS by Shen et. al. and understand the role of strange hyperons in th...

The analysis of SN1987A led Brown and Bethe (1995) to conclusion, that the maximum mass of cold neutron stars is low, M_max ~ 1.5M_sun. Such a low M_max, due to a kaon condensation in the stellar core, implies collapse of a too massive deleptonized protoneutron star into a black hole. This would naturally explain the lack of a neutron star in the SN1987A remnant. On the other hand, recent evaluation of mass of PSR J0751+1807 gives M_max > 2M_sun. This contradicts the original...

We study the effect of a dibaryon, S, in the mass range 1860 MeV < m_S < 2054 MeV, which is heavy enough not to disturb the stability of nuclei and light enough to possibly be cosmologically metastable. Such a deeply bound state can act as a baryon sink in regions of high baryon density and temperature. We find that the ambient conditions encountered inside a newly born neutron star are likely to sustain a sufficient population of hyperons to ensure that a population of S dib...

Witten's conjecture about strange quark matter (`Strange Matter') being the ground state of QCD at finite baryon number is presented and stars made of strange matter (`Strange Stars') are compared to neutron stars. The only observable way in which a strange star differs from a neutron star is in its early thermal history and a detailed study of strange star cooling is reported and compared to neutron star cooling. One concludes that future detection of thermal radiation from ...

The possibility of making stellar mass black holes in supernovae that otherwise produce viable Type II and Ib supernova explosions is discussed and estimates given of their number in the Milky Way Galaxy. Observational diagnostics of stellar mass black hole formation are reviewed. While the equation of state sets the critical mass, fall back during the explosion is an equally important (and uncertain) element in determining if a black hole is formed. SN 1987A may or may not h...

In this conference proceeding, we review important theoretical developments related to the production of strangeness in astrophysics. This includes its effects in supernova explosions, neutron stars, and compact-star mergers. We also discuss in detail how the presence of net strangeness affects the deconfinement to quark matter, expected to take place at large densities and/or temperatures. We conclude that a complete description of dense matter containing hyperons and strang...

We discuss the possible impact of strange quark matter on the evolution of core-collapse supernovae with emphasis on low critical densities for the quark-hadron phase transition. For such cases the hot proto-neutron star can collapse to a more compact hybrid star configuration hundreds of milliseconds after core-bounce. The collapse triggers the formation of a second shock wave. The latter leads to a successful supernova explosion and leaves an imprint on the neutrino signal....

We investigate the possibility of kaon condensation in the dense interior of neutron stars through the s--wave interaction of kaons with nucleons. We include nucleon--nucleon interactions by using simple parametrizations of realistic forces, and include electrons and muons in $\beta$--equilibrium. The conditions under which kaon condensed cores undergo a transition to quark matter containing strange quarks are also established. The critical density for kaon condensation lies ...