Strange-quark-matter Stars


Book Description

We investigate the implications of rapid rotation corresponding to the frequency of the new pulsar reported in the supernovae remnant SN1987A. It places very stringent conditions on the equation of state if the star is assumed to be bound by gravity alone. We find that the central energy density of the star must be greater than 13 times that of nuclear density to be stable against the most optimistic estimate of general relativistic instabilities. This is too high for the matter to consist of individual hadrons. We conclude that it is implausible that the newly discovered pulsar, if its half-millisecond signals are attributable to rotation, is a neutron star. We show that it can be a strange quark star, and that the entire family of strange stars can sustain high rotation if strange matter is stable at an energy density exceeding about 5.4 times that of nuclear matter. We discuss the conversion of a neutron star to strange star, the possible existence of a crust of heavy ions held in suspension by centrifugal and electric forces, the cooling and other features. 34 refs., 10 figs., 1 tab.




Quark Matter


Book Description

The meaning of "quark matter" is twofold: 1) It refers to compound states known as "subquarks" (the most fundamental constituents of matter), with quarks consisting of nuclear matter or "nucleons" (the constituents of the nucleus), and 2) compound states of quarks that consist of roughly equal numbers of up, down, and strange quarks, and which may be absolutely stable. Recently, both types of quark matter have become very intriguing subjects in physics and astronomy since the recently discovered Higgs boson, which may be taken as a composite object (possibly, a bound state of subquark-antisubquark pairs). Additionally, many recently observed compact stars have been considered "strange stars" (stars consisting of quark matter). In this book, these subjects in physics and astronomy are discussed without requiring readers to comprehend mathematical details. This book consists of three chapters: Chapter One: "Quark Matter and Strange Stars", Chapter Two: "Composites of Subquarks as Quark Matter", and Chapter Three: "Dark Energy, Dark Matter, and Strange Stars". Their contents include the following: In Chapter One, quark matter and strange stars are discussed in detail. In Chapter Two, the unified subquark model of all fundamental particles (quarks, leptons, and gauge and Higgs bosons) and forces (strong, electromagnetic, weak, and gravitational forces) is discussed in detail. In Chapter Three, pregeometry, in which the general theory of relativity for gravity can be derived as an approximate theory at long distances, is briefly reviewed. Furthermore, special and general theories of "inconstancy" in pregeometry in which fundamental physical constants may vary are introduced. Finally, possible solutions to the most puzzling problem in current cosmology of dark energy and dark matter in the universe are presented. Between Chapters One and Two, pictures of Dr. Abdus Salam added, as Dr. Salam was one of the founders of subquark models. Also, between Chapters Two and Three, pictures of Dr. Andrei Sakharov are added, as Dr. Sakharov was the founder of pregeometry.




Compact Stars


Book Description

A whole decades research collated, organised and synthesised into one single book! Following a 60-page review of the seminal treatises of Misner, Thorne, Wheeler and Weinberg on general relativity, Glendenning goes on to explore the internal structure of compact stars, white dwarfs, neutron stars, hybrids, strange quark stars, both the counterparts of neutron stars as well as of dwarfs. This is a self-contained treatment and will be of interest to graduate students in physics and astrophysics as well as others entering the field.







Neutron Stars 1


Book Description

The book gives an extended review of theoretical and observational aspects of neutron star physics. With masses comparable to that of the Sun and radii of about ten kilometres, neutron stars are the densest stars in the Universe. This book describes all layers of neutron stars, from the surface to the core, with the emphasis on their structure and equation of state. Theories of dense matter are reviewed, and used to construct neutron star models. Hypothetical strange quark stars and possible exotic phases in neutron star cores are also discussed. Also covered are the effects of strong magnetic fields in neutron star envelopes.




Quark Core Stars, Quark Stars and Strange Stars


Book Description

A recent one flavor quark matter equation of state is generalized to several flavors. It is shown that quarks undergo a first order phase transition. In addition, this equation of state depends on just one parameter in the two flavor case, two parameters in the three flavor case, and these parameters are constrained by phenomenology. This equation of state is then applied to the hadron-quark transition in neutron stars and the determination of quark star stability, the investigation of strange matter stability and possible strange star existence. 43 refs., 6 figs.




Pulsars as Astrophysical Laboratories for Nuclear and Particle Physics


Book Description

Pulsars, generally accepted to be rotating neutron stars, are dense, neutron-packed remnants of massive stars that blew apart in supernova explosions. They are typically about 10 kilometers across and spin rapidly, often making several hundred rotations per second. Depending on star mass, gravity compresses the matter in the cores of pulsars up to more than ten times the density of ordinary atomic nuclei, thus providing a high-pressure environment in which numerous particle processes, from hyperon population to quark deconfinement to the formation of Boson condensates, may compete with each other. There are theoretical suggestions of even more ""exotic"" processes inside pulsars, such as the formation of absolutely stable strange quark matter, a configuration of matter even more stable than the most stable atomic nucleus, ^T56Fe. In the latter event, pulsars would be largely composed of pure quark matter, eventually enveloped in nuclear crust matter. These features combined with the tremendous recent progress in observational radio and x-ray astronomy make pulsars nearly ideal probes for a wide range of physical studies, complementing the quest of the behavior of superdense matter in terrestrial collider experiments. Written by an eminent author, Pulsars as Astrophysical Laboratories for Nuclear and Particle Physics gives a reliable account of the present status of such research, which naturally is to be performed at the interface between nuclear physics, particle physics, and Einstein's theory of relativity.







Neutron Stars and the Quark Matter Equation of State


Book Description

Abstract: Neutron stars are among the densest objects in the universe. The uncertainty of the internal structure of these stars have led to various methods for modeling the behavior of matter at high density. In order to study the structure of compact stars, the Tolman- Oppenheimer-Volkoff (TOV) equations are solved to yield Mass-Radius curves of different neutron star structures. Such different structures investigated in this paper include stars of pure nuclear matter, stars of pure quark matter, and hybrid stars. These classes of stars are probably the only place in the universe where deconfined quark matter could exist. Because of the possibility of quark deconfinement, Quantum Chromodynamics (QCD) plays an important role in modeling the core of these stars. Although QCD is unsolved, we can still use some of the main principles to obtain some possible Equations of State (EoS) to be used in conjunction with the TOV equations. Although the EoS of the neutron star core is the bulk of this paper, we investigate the strange matter hypothesis, the masquerade of hybrid stars as nuclear stars, and the flavor camouflage in phase transitions, all through the use of the Vector Interaction Enhanced Bag Model (vBag). In the end, the results of this paper can be used in conjunction with observational astronomical data to constrain the equation of state for neutron stars. Since these compact stars are likely the only objects in the universe where the extreme density allows for quark deconfinement, it also provides us with one way to test out the QCD and QFT framework for high density nuclear matter.