NEW ASPECTS ON GRAVITATIONAL WAVE EMISSION BY NEUTRON STARS

2004 ◽  
Vol 13 (07) ◽  
pp. 1293-1296 ◽  
Author(s):  
GUILHERME F. MARRANGHELLO ◽  
CÉSAR A. Z. VASCONCELLOS ◽  
JOSÉ A. de FREITAS PACHECO ◽  
MANFRED DILLIG ◽  
HÉLIO T. COELHO
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Quark Matter ◽  
Inner Core ◽  
Compact Objects ◽  
Wave Emission

We discuss, in this work, new aspects related to the emission of gravitational waves by neutron stars, which undergo a phase transition, from nuclear to quark matter, in its inner core. Such a phase transition would liberate around 1052–53 erg of energy in the form of gravitational waves which, if detected, may shed some light in the structure of these compact objects and provide new insights on the equation of state of nuclear matter.

scholarly journals Simulating Binary Neutron Stars with Hybrid Equation of States: Gravitational Waves, Electromagnetic Signatures and Challenges for Numerical Relativity

Particles ◽  
2019 ◽  
Vol 2 (3) ◽  
pp. 365-384 ◽  
Author(s):  
Henrique Gieg ◽  
Tim Dietrich ◽  
Maximiliano Ujevic
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Quark Matter ◽  
Strange Quark ◽  
Numerical Relativity ◽  
Strange Quark Matter ◽  
Strong Phase ◽  
Equation Of States

The gravitational wave and electromagnetic signatures connected to the merger of two neutron stars allow us to test the nature of matter at supranuclear densities. Since the Equation of State governing the interior of neutron stars is only loosely constrained, there is even the possibility that strange quark matter exists inside the core of neutron stars. We investigate how strange quark matter cores affect the binary neutron star coalescence by performing numerical relativity simulations. Interestingly, the strong phase transition can cause a reduction of the convergence order of the numerical schemes to first order if the numerical resolution is not high enough. Therefore, an additional challenge is added in producing high-quality gravitational wave templates for Equation of States with a strong phase transition. Focusing on one particular configuration of an equal mass configuration consistent with GW170817, we compute and discuss the associated gravitational wave signal and some of the electromagnetic counterparts connected to the merger of the two stars. We find that existing waveform approximants employed for the analysis of GW170817 allow describing this kind of systems within the numerical uncertainties, which, however, are several times larger than for pure hadronic Equation of States, which means that even higher resolutions have been employed for an accurate gravitational wave model comparison. We also show that for the chosen Equation of State, quasi-universal relations describing the gravitational wave emission after the moment of merger seem to hold and that the electromagnetic signatures connected to our chosen setup would not be bright enough to explain the kilonova associated to GW170817.

ON THE EQUATION OF STATE IN EFFECTIVE QUARK THEORIES

2008 ◽  
Vol 23 (27n30) ◽  
pp. 2477-2480
Author(s):  
W. BENTZ ◽  
S. LAWLEY ◽  
A. W. THOMAS
Keyword(s):  
Phase Transition ◽  
Equation Of State ◽  
Nuclear Matter ◽  
Quark Matter ◽  
Quark Theory

We discuss the saturation mechanism for the nuclear matter equation of state in a chiral effective quark theory. The importance of the scalar polarizability of the nucleon is emphasized. The phase transition to color superconducting quark matter is also discussed.

scholarly journals NEUTRON STAR MATTER EQUATION OF STATE AND GRAVITATIONAL WAVE EMISSION

2005 ◽  
Vol 20 (31) ◽  
pp. 2335-2349 ◽  
Author(s):  
OMAR BENHAR
Keyword(s):  
Experimental Study ◽  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Gravitational Waves ◽  
Neutron Star Matter ◽  
Oscillation Modes ◽  
Nonradial Oscillation ◽  
Macroscopic Objects ◽  
Wave Emission

The EOS of strongly interacting matter at densities ten to fifteen orders of magnitude larger than the typical density of terrestrial macroscopic objects determines a number of neutron star properties, including the pattern of gravitational waves emitted following the excitation of nonradial oscillation modes. This paper reviews some of the approaches employed to model neutron star matter, as well as the prospects for obtaining new insights from the experimental study of gravitational waves emitted by neutron stars.

scholarly journals Population synthesis of accreting neutron stars emitting gravitational waves

2019 ◽  
Vol 488 (1) ◽  
pp. 99-110 ◽  
Author(s):  
Fabian Gittins ◽  
Nils Andersson
Keyword(s):  
Neutron Stars ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Population Synthesis ◽  
Spin Distribution ◽  
Synthetic Populations ◽  
Low Mass ◽  
Wave Emission ◽  
X Ray Binaries ◽  
Production Mechanisms

ABSTRACT The fastest-spinning neutron stars in low-mass X-ray binaries, despite having undergone millions of years of accretion, have been observed to spin well below the Keplerian break-up frequency. We simulate the spin evolution of synthetic populations of accreting neutron stars in order to assess whether gravitational waves can explain this behaviour and provide the distribution of spins that is observed. We model both persistent and transient accretion and consider two gravitational-wave-production mechanisms that could be present in these systems: thermal mountains and unstable rmodes. We consider the case of no gravitational-wave emission and observe that this does not match well with observation. We find evidence for gravitational waves being able to provide the observed spin distribution; the most promising mechanisms being a permanent quadrupole, thermal mountains, and unstable r modes. However, based on the resultant distributions alone, it is difficult to distinguish between the competing mechanisms.

scholarly journals NON-RADIAL OSCILLATIONS OF NEUTRON STARS AND THE DETECTION OF GRAVITATIONAL WAVES

2012 ◽  
Vol 18 ◽  
pp. 48-52 ◽  
Author(s):  
CECILIA CHIRENTI ◽  
PATRICK R. SILVEIRA ◽  
ODYLIO D. AGUIAR
Keyword(s):  
Neutron Stars ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Sensitivity Range ◽  
Wave Emission ◽  
Spherical Detector

We study the non-radial oscillations of relativistic neutron stars, in particular the (fundamental) f-modes, which are believed to be the most relevant for the gravitational wave emission of perturbed isolated stars. The expected frequencies of the f-modes are compared to the sensitivity range of Mario Schenberg, the Brazilian gravitational wave spherical detector.

scholarly journals Gravitational-Wave Asteroseismology as a Tool to Reveal the Equation of State of Relativistic Neutron Stars

2002 ◽  
Vol 185 ◽  
pp. 612-615
Author(s):  
Johannes Ruoff
Keyword(s):  
Neutron Star ◽  
Equation Of State ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Oscillation Modes

AbstractThe equation of state (EOS) is still the big unknown in the physics of neutron stars. An accurate measurement of both the mass and the radius of a neutron star would put severe constraints on the range of possible EOSs. I discuss how the parameters of the oscillation modes of a neutron star, measured from the emitted gravitational waves, can in principle be used to infer its mass and radius, and thus reveal its EOS.

scholarly journals The Equation of State for the Nucleonic and Hyperonic Core of Neutron Stars

2017 ◽  
Vol 34 ◽  
Author(s):  
Laura Tolos ◽  
Mario Centelles ◽  
Angels Ramos
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Inner Core ◽  
Heavy Ion ◽  
Saturation Properties ◽  
Ion Collisions ◽  
Pure Neutron Matter ◽  
Finite Nuclei ◽  
The Impact

AbstractWe re-examine the equation of state for the nucleonic and hyperonic inner core of neutron stars that satisfies the 2M⊙ observations as well as the recent determinations of stellar radii below 13 km, while fulfilling the saturation properties of nuclear matter and finite nuclei together with the constraints on the high-density nuclear pressure coming from heavy-ion collisions. The recent nucleonic FSU2R and hyperonic FSU2H models are updated in order to improve the behaviour of pure neutron matter at subsaturation densities. The corresponding nuclear matter properties at saturation, the symmetry energy, and its slope turn out to be compatible with recent experimental and theoretical determinations. We obtain the mass, radius, and composition of neutron stars for the two updated models and study the impact on these properties of the uncertainties in the hyperon–nucleon couplings estimated from hypernuclear data. We find that the onset of appearance of each hyperon strongly depends on the hyperon–nuclear uncertainties, whereas the maximum masses for neutron stars differ by at most 0.1M⊙, although a larger deviation should be expected tied to the lack of knowledge of the hyperon potentials at the high densities present in the centre of 2M⊙ stars. For easier use, we provide tables with the results from the FSU2R and FSU2H models for the equation of state and the neutron star mass–radius relation.

scholarly journals Probing Dense Nuclear Matter in the Laboratory: Experiments at FAIR and NICA

Universe ◽  
2021 ◽  
Vol 7 (6) ◽  
pp. 171
Author(s):  
Peter Senger
Keyword(s):  
Phase Transition ◽  
Neutron Star ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Quark Matter ◽  
Heavy Ion Collisions ◽  
Laboratory Experiments ◽  
Heavy Ion ◽  
High Density ◽  
Ion Collisions

The poorly known properties of high-density strongly-interacting matter govern the structure of neutron stars and the dynamics of neutron star mergers. New insight has been and will be gained by astronomical observations, such as the measurement of mass and radius of neutron stars, and the detection of gravitational waves emitted from neutron star mergers. Alternatively, information on the Nuclear Matter Equation-of-State (EOS) and on a possible phase transition from hadronic to quark matter at high baryon densities can be obtained from laboratory experiments investigating heavy-ion collisions. Detector systems dedicated to such experiments are under construction at the “Facility for Antiproton and Ion Research” (FAIR) in Darmstadt, Germany, and at the “Nuclotron-based Ion Collider fAcility” (NICA) in Dubna, Russia. In heavy-ion collisions at these accelerator centers, one expects the creation of baryon densities of up to 10 times saturation density, where quark degrees-of-freedom should emerge. This article reviews the most promising observables in heavy-ion collisions, which are used to probe the high-density EOS and possible phase transition from hadronic to quark matter. Finally, the facilities and the experimental setups will be briefly described.

scholarly journals Neutron Star Extreme Matter Observatory: A kilohertz-band gravitational-wave detector in the global network

2020 ◽  
Vol 37 ◽  
Author(s):  
K. Ackley ◽  
V. B. Adya ◽  
P. Agrawal ◽  
P. Altin ◽  
G. Ashton ◽  
...  
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Nuclear Physics ◽  
Global Network ◽  
Sensitivity Changes ◽  
The Cost ◽  
Event Rates

Abstract Gravitational waves from coalescing neutron stars encode information about nuclear matter at extreme densities, inaccessible by laboratory experiments. The late inspiral is influenced by the presence of tides, which depend on the neutron star equation of state. Neutron star mergers are expected to often produce rapidly rotating remnant neutron stars that emit gravitational waves. These will provide clues to the extremely hot post-merger environment. This signature of nuclear matter in gravitational waves contains most information in the 2–4 kHz frequency band, which is outside of the most sensitive band of current detectors. We present the design concept and science case for a Neutron Star Extreme Matter Observatory (NEMO): a gravitational-wave interferometer optimised to study nuclear physics with merging neutron stars. The concept uses high-circulating laser power, quantum squeezing, and a detector topology specifically designed to achieve the high-frequency sensitivity necessary to probe nuclear matter using gravitational waves. Above 1 kHz, the proposed strain sensitivity is comparable to full third-generation detectors at a fraction of the cost. Such sensitivity changes expected event rates for detection of post-merger remnants from approximately one per few decades with two A+ detectors to a few per year and potentially allow for the first gravitational-wave observations of supernovae, isolated neutron stars, and other exotica.

CONSTRAINTS ON THE HYPERON-SIGMA MESON COUPLING BY GW OBSERVATIONS

2007 ◽  
Vol 16 (09) ◽  
pp. 2847-2850 ◽  
Author(s):  
GUILHERME F. MARRANGHELLO ◽  
MOISÉS RAZEIRA ◽  
BARDO BODMANN ◽  
JOSÉ C. N. DE ARAUJO
Keyword(s):  
Equation Of State ◽  
Neutron Stars ◽  
Nuclear Matter ◽  
Gravitational Wave ◽  
Coupling Constant ◽  
Wave Source ◽  
Actual Knowledge ◽  
Meson Coupling ◽  
Sigma Meson ◽  
Field Theoretical Model

The next generation of gravitational wave observatories are promissing candidates to make the first detections. Once the detection occurs the GW characteristics permit to extract some information about the gravitational wave source. In the present work we focus on waves produced by neutron stars which can give stringent constraints on the nuclear matter equation of state. The microscopic description is based on a nonlinear field-theoretical model in order to construct such an equation of state. The model has free parameters, which from actual knowledge may not be pinned down by direct nuclear matter experiments. An important example is the hyperon-sigma meson coupling constant, currently determined by the spin-isospin SU(6) scheme. The coupling constant is of significant relevance for the structure of the equation of state, controlling its rigidity and, consequently, the properties of neutron stars and gravitational wave signals. We show, in this work, how one can constrain the hyperon-sigma meson coupling constant assuming the detection of a gravitational wave.

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