The Shadow of the Black Hole

2020 ◽  
Author(s):  
John W. Moffat
Keyword(s):  
United States ◽  
Black Holes ◽  
Black Hole ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Laser Interferometer ◽  
The United States ◽  
Gravitational Theory ◽  
The People

The author visits one of the two Laser Interferometer Gravitational- Wave Observatory (LIGO) sites in the United States, at Hanford, Washington. This is where scientists are detecting gravitational waves generated by faraway merging black holes and neutron stars. He meets the people who work there and has discussions with some of them. The director gives him a tour of the LIGO experimental installation, describing the work, the technological details of the apparatus, and answers his questions. On the final day of the visit, the author gives a talk to the LIGO group on gravitational waves and on an alternative gravitational theory.

scholarly journals Gravitational Waves from Mirror World

Physics ◽  
2019 ◽  
Vol 1 (1) ◽  
pp. 67-75
Author(s):  
Revaz Beradze ◽  
Merab Gogberashvili
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Dark Matter ◽  
Star Formation ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Binary Systems ◽  
Laser Interferometer ◽  
Matter Density ◽  
Mirror Matter

In this paper we consider the properties of the 10 confirmed by the LIGO (Laser Interferometer Gravitational-Wave Observatory) Collaboration gravitational wave signals from the black hole mergers. We want to explain non-observation of electromagnetic counterpart and higher then expected merging rates of these events, assuming the existence of their sources in the hidden mirror universe. Mirror matter, which interacts with our world only through gravity, is a candidate of dark matter and its density can exceed ordinary matter density five times. Since mirror world is considered to be colder, star formation there started earlier and mirror black holes had more time to pick up the mass and to create more binary systems within the LIGO reachable zone. In total, we estimate factor of 15 amplification of black holes merging rate in mirror world with respect to our world, which is consistent with the LIGO observations.

scholarly journals BLACK HOLES COLLISION IN GENERAL ROBINSON-TRAUTMAN SPACETIMES: WAVE FORMS AND THE EFFICIENCY OF THE GRAVITATIONAL WAVE EXTRACTION

2011 ◽  
Vol 03 ◽  
pp. 408-416
Author(s):  
H. P. DE OLIVEIRA ◽  
E. L. RODRIGUES
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Spectral Methods ◽  
Numerical Code ◽  
Numerical Evidence ◽  
Nonextensive Statistics ◽  
Wave Forms ◽  
Frontal Collisions

We analyze the non-frontal collisions of two Schwarzschild black holes in the realm of general Robinson-Trautman spacetimes using a numerical code based on spectral methods. In this process, two black holes collide and form a single black hole while a certain amount of the initial mass is carried away by gravitational waves. We determined the forms of the gravitational waves and the efficiency of this process for frontal and non-frontal collisions. We found numerical evidence that the distribution of mass qloss can be described by a function typically used in nonextensive statistics.

scholarly journals Quantum Black Holes in the Sky

Universe ◽  
2020 ◽  
Vol 6 (3) ◽  
pp. 43 ◽  
Author(s):  
Jahed Abedi ◽  
Niayesh Afshordi ◽  
Naritaka Oshita ◽  
Qingwen Wang
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Review Article ◽  
Compact Objects ◽  
Theoretical Underpinning ◽  
The Past ◽  
Einstein’S General Relativity

Black Holes are possibly the most enigmatic objects in our universe. From their detection in gravitational waves upon their mergers, to their snapshot eating at the centres of galaxies, black hole astrophysics has undergone an observational renaissance in the past four years. Nevertheless, they remain active playgrounds for strong gravity and quantum effects, where novel aspects of the elusive theory of quantum gravity may be hard at work. In this review article, we provide an overview of the strong motivations for why “Quantum Black Holes” may be radically different from their classical counterparts in Einstein’s General Relativity. We then discuss the observational signatures of quantum black holes, focusing on gravitational wave echoes as smoking guns for quantum horizons (or exotic compact objects), which have led to significant recent excitement and activity. We review the theoretical underpinning of gravitational wave echoes and critically examine the seemingly contradictory observational claims regarding their (non-)existence. Finally, we discuss the future theoretical and observational landscape for unraveling the “Quantum Black Holes in the Sky”.

scholarly journals Persamaan Gelombang Gravitasi untuk Teori Proca yang Digeneralisasi

2020 ◽  
Vol 5 ◽  
Author(s):  
Marliana Marliana ◽  
Agustina Widiyani ◽  
Azwar Sutiono ◽  
Agus Suroso ◽  
Freddy P. Zen
Keyword(s):  
Black Holes ◽  
Vector Field ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
General Equation ◽  
Direct Detection ◽  
Gravity Theory ◽  
Binary Black Holes ◽  
Massive Vector

<p class="AbstractEnglish"><strong>Abstract:</strong> The direct detection of gravitational waves from binary black holes and neutron stars have been taking a new oportunities to test teori of gravity.The gravitational wave is affected by the modification of a gravity theory during propagation at cosmological distances. By comparing general equation of gravtiational wave and modification of gravity theory, is obtained equation of gravitational wave for the generalized Proca theories. As a result, we find equation of gravitational wave for the generalized Proca theory. We conclude that the massive vector field affected propagation of gravitational wave.  we can use the result to test the generalized Proca theory.    </p><p class="AbstrakIndonesia"><strong>Abstrak:</strong> Dengan terdeteksinya gelombang gravitasi secara langsung dari biner lubang hitam dan bintang neutron menjadi kesempatan untuk dapat menguji teori gravitasi yang sedang dikembangkan.Gelombang gravitasi secara umum dipengaruhi oleh modifikasi teori gravitasi selama penjalarannya pada jarak kosmologi. Dengan membandingkan persamaan gelombang gravitasi dengan teori modifikasi yang dikembangkan, diperoleh persamaan umum gelombang gravitasi dari teori gravitasi yang dikembangkan. Pada artikel ini diperoleh persamaan gelombang gravitasi untuk teori Proca yang digeneralisasi. Dapat disimpulkan bahwa fungsi yang mengandung vektor medan masif dapat mempengaruhi gelombang gravitasi. Persamaan ini dapat digunakan untuk menguji teori Proca yang digeneralisasi.</p>

scholarly journals Gravitational waves observation: brief comments

2016 ◽  
Vol 38 (4) ◽  
Author(s):  
Mauro Cattani ◽  
José Maria Filardo Bassalo
Keyword(s):  
Black Holes ◽  
Gravitational Waves ◽  
United States Of America ◽  
Laser Interferometer ◽  
Binary Star ◽  
The United States ◽  
Basic Principles ◽  
Interferometric Technique ◽  
Relativistic Approach ◽  
Laser Interferometric

In preceding papers we have shown the fundamental aspects of the General Relativity (GR), of the emission and detection of gravitational waves (GW). With the same objective we analyze the two recent observations of the GW done by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the United States of America. These GW observations known as the GW150914 and GW151226 events are emitted by binary-star systems of black-holes (BBH). We present the basic principles of the laser interferometric technique that today is considered as the only one able to detect with certainty the GW. Using a simple relativistic approach we explain approximately the observed GW in the spiral stage.

Gravitational waves from neutron star binaries

2017 ◽  
Vol 26 (01n02) ◽  
pp. 1740015 ◽  
Author(s):  
Chang-Hwan Lee
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Future Prospect ◽  
Black Hole Binaries ◽  
Wave Detection ◽  
Low Mass ◽  
Merger Rate

With H. A. Bethe, G. E. Brown worked on the merger rate of neutron star binaries for the gravitational wave detection. Their prediction has to be modified significantly due to the observations of [Formula: see text] neutron stars and the detection of gravitational waves. There still, however, remains a possibility that neutron star-low mass black hole binaries are significant sources of gravitational waves for the ground-based detectors. In this paper, I review the evolution of neutron star binaries with super-Eddington accretion and discuss the future prospect.

4. Gravitational waves

2017 ◽  
pp. 46-57
Author(s):  
Timothy Clifton
Keyword(s):  
Gravitational Field ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Laser Interferometer ◽  
Space Time ◽  
Binary Pulsar ◽  
Set Up ◽  
The Waves

As stars collapse they eject huge amounts of mass and energy; their gravitational field changes rapidly and, therefore, so does the curvature of the space-time around them. If the curvature of space-time is pushed out of equilibrium, by the motion of mass or energy, this disturbance travels outwards as waves. ‘Gravitational waves’ explains the effect of a gravitational wave: in a binary pulsar, the waves carry energy away from the system so that the two neutron stars slowly circle in towards each other. Gravitational waves were first detected in 2015 by the Laser Interferometer Gravitational-Wave Observatory in America. There are also plans to set up a detector in space.

scholarly journals The New Astronomy: Observing Our Universe With Light and Gravity

2019 ◽  
Vol 7 ◽  
Author(s):  
Joey Shapiro Key ◽  
LIGO Scientific Collaboration
Keyword(s):  
Black Holes ◽  
South America ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Gamma Ray ◽  
Distant Galaxy ◽  
The World ◽  
The Galaxy ◽  
First Time

On a summer day in 2017, astronomers around the world received a message about an exciting collision of two stars far, far away. The message was sent by a team of astronomers from the LIGO and Virgo observatories. These new observatories are very different from the telescopes we have used to study our Universe up until now. LIGO and Virgo are gravitational wave observatories, listening for quiet ripples in spacetime created by the collisions of distant black holes and neutron stars. On August 17, 2017 LIGO and Virgo detected a signal that astronomers named GW170817, from the collision of two neutron stars. Less than two seconds later, NASA's Fermi satellite caught a signal, known as a gamma-ray burst, and within minutes, telescopes around the world began searching the sky. Telescopes in South America found the location of the collision in a distant galaxy known as NGC 4993. For the weeks and months that followed, astronomers watched the galaxy and the fading light from the collision. This is a new kind of multi-messenger astronomy where, for the first time, the same event was observed by both gravitational waves and light.

scholarly journals Gravitational waves: A review on the future astronomy

2022 ◽  
pp. 38-50
Author(s):  
Rabinarayan Swain ◽  
Priyasmita Panda ◽  
Hena Priti Lima ◽  
Bijayalaxmi Kuanar ◽  
Biswajit Dalai
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Dark Energy ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Binary Systems ◽  
Hubble Constant ◽  
New Approach ◽  
Different Sources

Detection of Gravitational waves opened a new path for cosmological study in a new approach. From the detection of gravitational waves signal by advanced LIGO, its research climbed the peak. After the collaboration of LIGO and Virgo, several observations get collected from different sources of binary systems like black holes, binary neutron stars even both binary black hole and neutron star. The rigorous detection of gravitational signals may provide an additional thrust in the study of complex binary systems, dark matter, dark energy, Hubble constant, etc. In this review paper, we went through multiple research manuscripts to analyze gravitational wave signals. Here we have reviewed the history and current situation of gravitational waves detection, and we explained the concept and process of detection. Also, we go through different parts of a detector and their working. Then multiple gravitational wave signals are focused, originated from various sources and then found correlation between them. From this, the contribution of gravitational waves in different fields like complex binary systems (black holes, neutron stars), dark matter, dark energy and Hubble Constant have been discussed in this manuscript.

scholarly journals Localizing merging black holes with sub-arcsecond precision using gravitational-wave lensing

2020 ◽  
Vol 498 (3) ◽  
pp. 3395-3402 ◽  
Author(s):  
Otto A Hannuksela ◽  
Thomas E Collett ◽  
Mesut Çalışkan ◽  
Tjonnie G F Li
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Physical Properties ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Hubble Constant ◽  
Host Galaxy ◽  
Binary Black Hole ◽  
Proof Of Principle

ABSTRACT The current gravitational-wave (GW) localization methods rely mainly on sources with electromagnetic counterparts. Unfortunately, a binary black hole does not emit light. Due to this, it is generally not possible to localize these objects precisely. However, strongly lensed gravitational waves, which are forecasted in this decade, could allow us to localize the binary by locating its lensed host galaxy. Identifying the correct host galaxy is challenging because there are hundreds to thousands of other lensed galaxies within the sky area spanned by the GW observation. However, we can constrain the lensing galaxy’s physical properties through both GW and electromagnetic observations. We show that these simultaneous constraints allow one to localize quadruply lensed waves to one or at most a few galaxies with the LIGO/Virgo/Kagra network in typical scenarios. Once we identify the host, we can localize the binary to two sub-arcsec regions within the host galaxy. Moreover, we demonstrate how to use the system to measure the Hubble constant as a proof-of-principle application.

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