Systematic Study of Binary Neutron Star Mergers with Neutrinos and Pions PDF Download

Author: Vimal Vijayan
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Author: Praveen Manoharan
Publisher: Springer Nature
ISBN: 3658368411
Category : Science
Languages : en
Pages : 77

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In the last 25 years, an extensive body of work has developed various equation of state independent - or (approximately) universal - relations that allow for the inference of neutron star parameters from gravitational wave observations. These works, however, have mostly been focused on singular neutron stars, while our observational efforts at the present, and in the near future, will be focused on binary neutron star (BNS) mergers. In light of these circumstances, the last five years have also given rise to more attempts at developing universal relations that relate BNS pre-merger neutron stars to stellar parameters of the post-merger object, mostly driven by numerical relativity simulations. In this thesis a first attempt at perturbatively deriving universal relations for binary neutron star mergers with long-lived neutron star remnants is presented. The author succeeds in confirming previous results relating pre-merger binary tidal deformabilities to the f-mode frequency of the post-merger object. Combining this result with recent advances of computing the f-mode frequency of fast rotating neutron stars, he also derives a combined relation that relates the pre-merger binary tidal deformability of a BNS to the effective compactness of a long-lived neutron star remnant. Finally, he also proposes a direct relation between these quantities with improved accuracy.

Author:
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Category :
Languages : en
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Author: Matteo Breschi
Publisher:
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Languages : en
Pages : 0

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The joint detection of the GW170817 and its electromagnetic counterparts was a milestone in multi-messenger astronomy. We investigate the observational constraints on the neutron star equation of state provided by multi-messenger data of binary neutron star mergers, analyzing the gravitational-wave transient GW170817 and its kilonova counterpart AT2017gfo and exploring new scenarios with next-generation gravitational-wave detectors. The LIGO-Virgo data of GW170817 are analyzed using different template models focusing on the implications for neutron star matter properties. We study the systematic tidal errors between current gravitational-wave models finding that waveform systematics dominate over statistical errors at signal-to-noise ratio ≳ 100. We study AT2017gfo using semi-analytical model showing that observational data favor multi-component anisotropic geometries to spherically symmetric profiles. By joining GW170817 and AT2017gfo information with the NICER measurements, we infer the neutron star equation of state constraining the radius of a 1.4M☉ neutron star to 12.39+0.70-0.65 km and the maximum mass MTOV to 2.08+0.16-0.09 M☉ (90% credible level). Finally, we explore future constraints on extreme-matter delivered by postmerger gravitational-waves from binary neutron star merger remnants. These transients can be detected with matched-filtering techniques and numerical-relativity-informed models for signal-to-noise ratios ≳ 7. Postmerger remnants can probe the high-density regimes of the nuclear equation of state, allowing the inference of the maximum neutron star mass MTOV with an accuracy of 12% (90% max credible level). Moreover, postmerger transients can be used to infer the presence of non-nucleonic matter phases through the inference of softening of the equation of state. For particular binary configurations, softening effects of the equation of state can lead to breaking of quasiuniversal properties and earlier collapse into black hole.

Author: Omar Benhar
Publisher: CRC Press
ISBN: 1040044743
Category : Science
Languages : en
Pages : 383

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Over the last decade, astrophysical observations of neutron stars — both as isolated and binary sources — have paved the way for a deeper understanding of the structure and dynamics of matter beyond nuclear saturation density. The mapping between astrophysical observations and models of dense matter based on microscopic dynamics has been poorly investigated so far. However, the increased accuracy of present and forthcoming observations may be instrumental in resolving the degeneracy between the predictions of different equations of state. Astrophysical and laboratory probes have the potential to paint to a new coherent picture of nuclear matter — and, more generally, strong interactions — over the widest range of densities occurring in the Universe. This book provides a self-contained account of neutron star properties, microscopic nuclear dynamics and the recent observational developments in multimessenger astronomy. It also discusses the unprecedented possibilities to shed light on long standing and fundamental issues, such as the validity of the description of matter in terms of pointlike baryons and leptons and the appearance of deconfined quarks in the high density regime. It will be of interest to researchers and advanced PhD students working in the fields of Astrophysics, Gravitational Physics, Nuclear Physics and Particle Physics. Key Features: Reviews state-of-the-art theoretical and experimental developments Self-contained and cross-disciplinary While being devoted to a very lively and fast developing field, the book fundamentally addresses methodological issues. Therefore, it will not be subject to fast obsolescence. Omar Benhar is an INFN Emeritus Research Director, and has been teaching Relativistic Quantum Mechanics, Quantum Electrodynamics and Structure of Compact Stars at “Sapienza” University of Rome for over twenty years. He has worked extensively in the United States, and since 2013 has served as an adjunct professor at the Center for Neutrino Physics of Virginia Polytechnic Institute and State University. Prof. Benhar has authored or co-authored three textbooks on Relativistic Quantum Mechanics, Gauge Theories, and Structure and Dynamics of Compact Stars, and published more than one hundred scientific papers on the theory of many-particle systems, the structure of compact stars and the electroweak interactions of nuclei. Alessandro Lovato is a physicist at Argonne National Laboratory and an INFN researcher in Trento. His research in theoretical nuclear physics focuses on consistently modeling the self-emerging properties of atomic nuclei and neutron-star matter in terms of the microscopic interactions among the constituent protons and neutrons. He has co-authored more than eighty scientific publications on the theory of many-particle systems, the structure of compact stars, and the electroweak interactions of nuclei. He is at the forefront of high-performance computing applied to solving the quantum many-body problem. Andrea Maselli is an Associate Professor at the Gran Sasso Science Institute, in L’Aquila, where he teaches Gravitation and Cosmology and Physics of Black Hole. His research focuses on strong gravity, which plays a crucial role in many astrophysical phenomena involving black hole and neutron stars, representing natural laboratories to test fundamental physics. Prof. Maselli has co-authored more than eighty scientific papers on the modelling of black holes and neutron stars in General Relativity and extension thereof, their gravitational wave emission, and on tests of gravity in the strong filed regime. He is active in various collaborations aimed at developing next generation of gravitational wave detectors, such as the LISA satellite, the Einstein Telescope, and the Lunar Gravitational Wave Antenna. Francesco Pannarale is an Associate Professor at “Sapienza” Univeristy of Rome, where he teaches Gravitational Waves, Compact Objects and Black Holes, Computing Methods for Physics, and Electromagnetism. His research interests are in gravitational-wave physics and multimessenger astronomy, and they range from modelling compact binary sources to data analysis. He has co-authored over one hundred and eighty scientific publications and was at the forefront of the joint observation of GW170817 and GRB 170817A. He is currently serving as co-chair of the LIGO-Virgo-KAGRA Data Analysis Council.

Author: Varun B. Bhalerao
Publisher: Universal-Publishers
ISBN: 1612339441
Category : Science
Languages : en
Pages : 170

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This book centers around the study of neutron stars, especially those in massive binary systems. To this end, it has two distinct components: the observational study of neutron stars in massive binaries with a goal of measuring neutron star masses and participation in NuSTAR, the first imaging hard X-ray mission, one that is extremely well suited to the study of massive binaries and compact objects in our Galaxy. The Nuclear Spectroscopic Telescope Array (NuSTAR) is a NASA Small Explorer mission that will carry the first focusing high energy X-ray telescope to orbit. NuSTAR has an order-of-magnitude better angular resolution and has two orders of magnitude higher sensitivity than any currently orbiting hard X- ray telescope. I worked to develop, calibrate, and test CdZnTe detectors for NuSTAR. I describe the CdZnTe detectors in comprehensive detail here-from readout procedures to data analysis. Detailed calibration of detectors is necessary for analyzing astrophysical source data obtained by the NuSTAR. I discuss the design and implementation of an automated setup for calibrating flight detectors, followed by calibration procedures and results. Neutron stars are an excellent probe of fundamental physics. The maximum mass of a neutron star can put stringent constraints on the equation of state of matter at extreme pressures and densities. From an astrophysical perspective, there are several open questions in our understanding of neutron stars. What are the birth masses of neutron stars? How do they change in binary evolution? Are there multiple mechanisms for the formation of neutron stars? Measuring masses of neutron stars helps answer these questions. Neutron stars in high-mass X-ray binaries have masses close to their birth mass, providing an opportunity to disentangle the role of "nature" and "nurture" in the observed mass distributions. In 2006, masses had been measured for only six such objects, but this small sample showed the greatest diversity in masses among all classes of neutron star binaries. Intrigued by this diversity-which points to diverse birth masses-we undertook a systematic survey to measure the masses of neutron stars in nine high-mass X-ray binaries. In this book, I present results from this ongoing project.

Author: Werner Becker
Publisher: Springer Science & Business Media
ISBN: 354076965X
Category : Science
Languages : en
Pages : 702

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Neutron stars are the most compact astronomical objects in the universe which are accessible by direct observation. Studying neutron stars means studying physics in regimes unattainable in any terrestrial laboratory. Understanding their observed complex phenomena requires a wide range of scientific disciplines, including the nuclear and condensed matter physics of very dense matter in neutron star interiors, plasma physics and quantum electrodynamics of magnetospheres, and the relativistic magneto-hydrodynamics of electron-positron pulsar winds interacting with some ambient medium. Not to mention the test bed neutron stars provide for general relativity theories, and their importance as potential sources of gravitational waves. It is this variety of disciplines which, among others, makes neutron star research so fascinating, not only for those who have been working in the field for many years but also for students and young scientists. The aim of this book is to serve as a reference work which not only reviews the progress made since the early days of pulsar astronomy, but especially focuses on questions such as: "What have we learned about the subject and how did we learn it?", "What are the most important open questions in this area?" and "What new tools, telescopes, observations, and calculations are needed to answer these questions?". All authors who have contributed to this book have devoted a significant part of their scientific careers to exploring the nature of neutron stars and understanding pulsars. Everyone has paid special attention to writing educational comprehensive review articles with the needs of beginners, students and young scientists as potential readers in mind. This book will be a valuable source of information for these groups.

Author: D. Blaschke
Publisher: Springer
ISBN: 3540445781
Category : Science
Languages : en
Pages : 521

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Neutron stars are the densest observable bodies in our universe. Born during the gravitational collapse of luminous stars - a birth heralded by spectacular supernova explosions - they open a window on a world where the state of the matter and the strengths of the fields are anything but ordinary. This book is a collection of pedagogical lectures on the theory of neutron stars, and especially their interiors, at the forefront of current research. It addresses graduate students and researchers alike, and should be particularly suitable as a text bridging the gap between standard textbook material and the research literature.

Author: Andrew P. Wass
Publisher: Nova Publishers
ISBN: 9781594543517
Category : Science
Languages : en
Pages : 158

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Neutron stars are the collapsed cores of some massive stars. They pack roughly the mass of our Sun into a region the size of a city. Neutron stars are believed to form in supernovae such as the one that formed the Crab Nebula. The stars that eventually become neutron stars are thought to start out with about 15 to 30 times the mass of our sun. It appears that for initial masses much less than 15 solar masses the star becomes a white dwarf, whereas for initial masses a lot higher than 30 solar masses a black hole results instead. It is estimated that there are 108 neutron stars in our galaxy. About 1000 of these have actually been observed by astronomers so far. This new book presents recent and important research results in the field.

Author: Luke Bovard
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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When binary systems of neutron stars merge, a very small fraction of their rest mass is ejected, either dynamically or secularly. This material is neutron-rich and its nucleosynthesis provides the astrophysical site for the production of heavy elements in the Universe, together with a kilonova signal confirming neutron-star mergers as the origin of short gamma-ray bursts. We perform full general-relativistic simulations of binary neutron-star mergers employing three different nuclear-physics equations of state (EOSs), considering both equal- and unequal-mass configurations, and adopting a leakage scheme to account for neutrino radiative losses. Using a combination of techniques, we carry out an extensive and systematic study of the hydrodynamical, thermodynamical, and geometrical properties of the matter ejected dynamically, employing the WinNet nuclear-reaction network to recover the relative abundances of heavy elements produced by each configurations. Among the results obtained, three are particularly important. First, we find that, within the sample considered here, both the properties of the dynamical ejecta and the nucleosynthesis yields are robust against variations of the EOS and masses. Second, using a conservative but robust criterion for unbound matter, we find that the amount of ejected mass is ≲10-3 M⊙, hence at least one order of magnitude smaller than what normally assumed in modelling kilonova signals. Finally, using a simplified and gray-opacity model we assess the observability of the infrared kilonova emission finding, that for all binaries the luminosity peaks around ∼1=2 day in the H-band, reaching a maximum magnitude of -13, and decreasing rapidly after one day.