Gravitational Waves from Binary Neutron Stars Systems

Gravitational Waves from Binary Neutron Stars Systems PDF Author: Reetika Dudi
Publisher:
ISBN:
Category :
Languages : de
Pages :

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Book Description
The first observation of gravitational waves from a merger of binary neutron stars (BNS) along with measurements of electromagnetic counterpart has led the beginning of multi-messenger gravitational wave astronomy. In this thesis, we investigate various gravitational waveform models. These models are employed for extracting source properties from the gravitational wave signal from the BNS merger. We perform parameter estimation studies in order to deduce the systematics among these models. We employ different injection scenarios to understand the biases that occur due to differences in the physics included in different waveform models. We present the construction of hybrid waveforms and discuss their applications as a full waveform, e.g., for validation of other waveform models and to check the performance of the models by performing mismatch calculations and parameter estimation studies where hybrid waveforms used as a substitute for a real signal. Based on the systematics study, we show a few of the waveform models give biased esti- mates of the parameters for specific injection scenarios. We improve those models and present the results of the improved models. In the context of having an accurate yet fast-to-evaluate waveform model, we review reduced-order-modeling techniques and present its application for the multipolar TEOBResum model. Furthermore, to validate and tune analytical models, and to investigate the last few orbits near the merger and after the merger, numerical simulations are inevitable. We evaluate the performance of an initial data generating code, called new SGRID code for BNS systems. With the upcoming advance detectors, it is highly likely that events with extreme source properties will get observed. Therefore, in this thesis, we show preliminary results for numerical simulations of BNS mergers with high spins. We vary equation-of-states (EOSs) and spins to investigate the effects of spin and EOS on the dynamics and gravitational waves.

Gravitational Waves from Binary Neutron Stars Systems

Gravitational Waves from Binary Neutron Stars Systems PDF Author: Reetika Dudi
Publisher:
ISBN:
Category :
Languages : de
Pages :

Get Book Here

Book Description
The first observation of gravitational waves from a merger of binary neutron stars (BNS) along with measurements of electromagnetic counterpart has led the beginning of multi-messenger gravitational wave astronomy. In this thesis, we investigate various gravitational waveform models. These models are employed for extracting source properties from the gravitational wave signal from the BNS merger. We perform parameter estimation studies in order to deduce the systematics among these models. We employ different injection scenarios to understand the biases that occur due to differences in the physics included in different waveform models. We present the construction of hybrid waveforms and discuss their applications as a full waveform, e.g., for validation of other waveform models and to check the performance of the models by performing mismatch calculations and parameter estimation studies where hybrid waveforms used as a substitute for a real signal. Based on the systematics study, we show a few of the waveform models give biased esti- mates of the parameters for specific injection scenarios. We improve those models and present the results of the improved models. In the context of having an accurate yet fast-to-evaluate waveform model, we review reduced-order-modeling techniques and present its application for the multipolar TEOBResum model. Furthermore, to validate and tune analytical models, and to investigate the last few orbits near the merger and after the merger, numerical simulations are inevitable. We evaluate the performance of an initial data generating code, called new SGRID code for BNS systems. With the upcoming advance detectors, it is highly likely that events with extreme source properties will get observed. Therefore, in this thesis, we show preliminary results for numerical simulations of BNS mergers with high spins. We vary equation-of-states (EOSs) and spins to investigate the effects of spin and EOS on the dynamics and gravitational waves.

The Physics and Astrophysics of Neutron Stars

The Physics and Astrophysics of Neutron Stars PDF Author: Luciano Rezzolla
Publisher: Springer
ISBN: 3319976168
Category : Science
Languages : en
Pages : 811

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Book Description
This book summarizes the recent progress in the physics and astrophysics of neutron stars and, most importantly, it identifies and develops effective strategies to explore, both theoretically and observationally, the many remaining open questions in the field. Because of its significance in the solution of many fundamental questions in nuclear physics, astrophysics and gravitational physics, the study of neutron stars has seen enormous progress over the last years and has been very successful in improving our understanding in these fascinating compact objects. The book addresses a wide spectrum of readers, from students to senior researchers. Thirteen chapters written by internationally renowned experts offer a thorough overview of the various facets of this interdisciplinary science, from neutron star formation in supernovae, pulsars, equations of state super dense matter, gravitational wave emission, to alternative theories of gravity. The book was initiated by the European Cooperation in Science and Technology (COST) Action MP1304 “Exploring fundamental physics with compact stars” (NewCompStar).

Gravitational Waves: A New Window to the Universe

Gravitational Waves: A New Window to the Universe PDF Author: Rosalba Perna
Publisher: Frontiers Media SA
ISBN: 2889669416
Category : Science
Languages : en
Pages : 73

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Book Description


Initial Data Generation and Dynamical Simulations of Binary Neutron Star Systems

Initial Data Generation and Dynamical Simulations of Binary Neutron Star Systems PDF Author: Tanmayee Gupte
Publisher:
ISBN:
Category : Double stars
Languages : en
Pages : 0

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Book Description
"The recent detection of gravitational waves (GWs) from a system of binary neutron stars (BNS) in coincidence with electromagnetic observations has launched a new era of multimessenger astrophysics. In light of the complementary knowledge to be gained through simultaneous observations, BNS mergers are one of the main targets for terrestrial GW interferometric detectors. These observations may prove critical in understanding the equation of state (EOS) of the nuclear matter inside the neutron star core, which is still poorly constrained given current observations. Understanding the neutron star (NS) EOS is critical for binary parameter estimation, and will hopefully aid in the prediction and detection of additional GW signals for systems with varying NS masses. While configurations of binary neutron stars having mass ratios far from unity are of great interest because of their potential observational signatures, generating accurate initial data for such systems has historically proven to be difficult, and relatively limited work has been done to date in simulating unequal-mass BNS because of a variety of numerical difficulties. In this work, we have modified the publicly available LORENE binary initial data code to advance our ability to construct unequal-mass BNS initial data, and used our results to initiate dynamical evolutions of BNS mergers performed using the Einstein Toolkit. We have investigated the quality of the initial data produced by our modified version of LORENE by evaluating a number of metrics, particularly the conservation of the Hamiltonian constraint when data are interpolated onto a grid for use in dynamical simulations. Here we discuss the process by which we generate initial data and use it for launching dynamical simulations, as well as our analysis of the dynamics of the merger for varying mass ratios and different EOSs represented as simple polytropes and piecewise polytropes. In particular, we analyze the relationship between the BNS mass ratio, EOS, and the ejected mass during the merger, and classify the fate of the merger remnant produced in each case."--Abstract.

Gravitational-Wave Physics and Astronomy

Gravitational-Wave Physics and Astronomy PDF Author: Jolien D. E. Creighton
Publisher: John Wiley & Sons
ISBN: 3527636048
Category : Science
Languages : en
Pages : 403

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Book Description
This most up-to-date, one-stop reference combines coverage of both theory and observational techniques, with introductory sections to bring all readers up to the same level. Written by outstanding researchers directly involved with the scientific program of the Laser Interferometer Gravitational-Wave Observatory (LIGO), the book begins with a brief review of general relativity before going on to describe the physics of gravitational waves and the astrophysical sources of gravitational radiation. Further sections cover gravitational wave detectors, data analysis, and the outlook of gravitational wave astronomy and astrophysics.

Black Holes, White Dwarfs, and Neutron Stars

Black Holes, White Dwarfs, and Neutron Stars PDF Author: Stuart L. Shapiro
Publisher: John Wiley & Sons
ISBN: 3527617671
Category : Science
Languages : en
Pages : 663

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Book Description
This self-contained textbook brings together many different branches of physics--e.g. nuclear physics, solid state physics, particle physics, hydrodynamics, relativity--to analyze compact objects. The latest astronomical data is assessed. Over 250 exercises.

Gravitational Waves from Binary Neutron Stars and Test Particle Inspirals Into Black Holes

Gravitational Waves from Binary Neutron Stars and Test Particle Inspirals Into Black Holes PDF Author: Tanja Petra Hinderer
Publisher:
ISBN: 9780549967712
Category :
Languages : en
Pages : 341

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Book Description
(I) We show that ground-based gravitational wave detectors may be able to constrain the nuclear equation of state using the early, relatively clean portion of the signal of detected neutron star neutron star inspirals.

Numerical Relativity

Numerical Relativity PDF Author: Thomas W. Baumgarte
Publisher: Cambridge University Press
ISBN: 1139643177
Category : Science
Languages : en
Pages : 717

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Book Description
Aimed at students and researchers entering the field, this pedagogical introduction to numerical relativity will also interest scientists seeking a broad survey of its challenges and achievements. Assuming only a basic knowledge of classical general relativity, the book develops the mathematical formalism from first principles, and then highlights some of the pioneering simulations involving black holes and neutron stars, gravitational collapse and gravitational waves. The book contains 300 exercises to help readers master new material as it is presented. Numerous illustrations, many in color, assist in visualizing new geometric concepts and highlighting the results of computer simulations. Summary boxes encapsulate some of the most important results for quick reference. Applications covered include calculations of coalescing binary black holes and binary neutron stars, rotating stars, colliding star clusters, gravitational and magnetorotational collapse, critical phenomena, the generation of gravitational waves, and other topics of current physical and astrophysical significance.

Physics of Gravitational Waves

Physics of Gravitational Waves PDF Author: Arun Kenath
Publisher: Springer Nature
ISBN: 3031304632
Category : Science
Languages : en
Pages : 61

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Book Description
This book provides a concise introduction to the physics of gravitational waves. It is aimed at graduate-level students and PhD scholars. Ever since the discovery of gravitational waves in 2016, gravitational wave astronomy has been adding to our understanding of the universe. Gravitational waves have been detected in the past few years from several transient events such as merging stellar-mass black holes, binary neutron stars, etc. These waves have frequencies in a band ranging from a few hundred hertz to around a kilohertz to which LIGO type instruments are sensitive. LISA will be sensitive to much lower range of frequencies from SMBH mergers. Apart from these cataclysmic burst events, there are innumerable sources of radiation which are continuously emitting gravitational waves of all frequencies. These include a whole mass range of compact binary and isolated compact objects and close planetary stellar entities. This book discusses the gravitational wave background produced in typical frequency ranges from such sources emitting over a Hubble time and the fluctuations in the h values measured in the usual devices. Also discussed are the high-frequency thermal background gravitational radiation from hot stellar interiors and newly formed compact objects. The reader will also learn how gravitational waves provide a testing tool for various theories of gravity, i.e. general relativity and extended theories of gravity, and will be the definitive test for general relativity.

Relativistic Hydrodynamics

Relativistic Hydrodynamics PDF Author: Luciano Rezzolla
Publisher: OUP Oxford
ISBN: 0191509914
Category : Science
Languages : en
Pages : 752

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Book Description
Relativistic hydrodynamics is a very successful theoretical framework to describe the dynamics of matter from scales as small as those of colliding elementary particles, up to the largest scales in the universe. This book provides an up-to-date, lively, and approachable introduction to the mathematical formalism, numerical techniques, and applications of relativistic hydrodynamics. The topic is typically covered either by very formal or by very phenomenological books, but is instead presented here in a form that will be appreciated both by students and researchers in the field. The topics covered in the book are the results of work carried out over the last 40 years, which can be found in rather technical research articles with dissimilar notations and styles. The book is not just a collection of scattered information, but a well-organized description of relativistic hydrodynamics, from the basic principles of statistical kinetic theory, down to the technical aspects of numerical methods devised for the solution of the equations, and over to the applications in modern physics and astrophysics. Numerous figures, diagrams, and a variety of exercises aid the material in the book. The most obvious applications of this work range from astrophysics (black holes, neutron stars, gamma-ray bursts, and active galaxies) to cosmology (early-universe hydrodynamics and phase transitions) and particle physics (heavy-ion collisions). It is often said that fluids are either seen as solutions of partial differential equations or as "wet". Fluids in this book are definitely wet, but the mathematical beauty of differential equations is not washed out.