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 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 A binary population synthesis study on gravitational wave sources

2015 ◽  
Vol 11 (A29B) ◽  
pp. 365-366
Author(s):  
Liu Jinzhong ◽  
Zhang Yu
Keyword(s):  
Black Holes ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Gamma Ray ◽  
Theoretical Study ◽  
Compact Objects ◽  
Population Synthesis ◽  
Observational Astronomy ◽  
X Ray ◽  
X Ray Binaries

AbstractGravitational waves (GW) are a natural consequence of Einstein's theory of gravity (general relativity), and minute distortions of space-time. Gravitational Wave Astronomy is an emerging branch of observational astronomy which aims to use GWs to collect observational data about objects such as neutron stars and black holes, about events such as supernovae and about the early universe shortly after the big bang.This field will evolve to become an established component of 21st century multi-messenger astronomy, and will stand shoulder-to-shoulder with gamma-ray, x-ray, optical, infrared and radio astronomers in exploring the cosmos. In this paper, we state a recent theoretical study on GW sources, and present the results of our studies on the field using a binary population synthesis (BPS) approach, which was designed to investigate the formation of many interesting binary-related objects, including close double white dwarfs, AM CVn stars, ultra-compact X-ray binaries(UCXBs), double neutron stars, double stellar black holes. Here we report how BPS can be used to determine the GW radiation from double compact objects.

scholarly journals The analogy of K-correction in the topic of gamma-ray bursts

2018 ◽  
Vol 14 (S346) ◽  
pp. 380-382
Author(s):  
Levente Borvák ◽  
Attila Mészáros ◽  
Jakub Řípa
Keyword(s):  
Black Holes ◽  
Neutron Stars ◽  
Gravitational Waves ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Surprising Result ◽  
Massive Black Holes ◽  
Strongly Connected

AbstractIt is well-known that there are two types of gamma-ray bursts (GRBs): short/hard and long/soft ones, respectively. The long GRBs are coupled to supernovae, but the short ones are associated with the so called macronovae (also known as kilonovae), which can serve as the sources of gravitational waves as well. The kilonovae can arise from the merging of two neutron-stars. The neutron stars can be substituded by more massive black holes as well. Hence, the topic of gamma-ray bursts (mainly the topic of short ones) and the topic of massive binaries, are strongly connected.In this contribution, the redshifts of GRBs are studied. The surprising result - namely that the apparently fainter GRBs can be in average at smaller distances - is discussed again. In essence, the results of Mészáros et al. (2011) are studied again using newer samples of GRBs. The former result is confirmed by the newer data.

scholarly journals Future merger of the Milky Way with the Andromeda galaxy and the fate of their supermassive black holes

2020 ◽  
Vol 642 ◽  
pp. A30
Author(s):  
Riccardo Schiavi ◽  
Roberto Capuzzo-Dolcetta ◽  
Manuel Arca-Sedda ◽  
Mario Spera
Keyword(s):  
Black Holes ◽  
Gravitational Wave ◽  
Relative Motion ◽  
Milky Way ◽  
Close Approach ◽  
Supermassive Black Holes ◽  
Andromeda Galaxy ◽  
The Galaxy ◽  
Inner Region ◽  
First Time

Our Galaxy and the nearby Andromeda galaxy (M 31) are the most massive members of the Local Group, and they seem to be a bound pair, despite the uncertainties on the relative motion of the two galaxies. A number of studies have shown that the two galaxies will likely undergo a close approach in the next 4−5 Gyr. We used direct N-body simulations to model this interaction to shed light on the future of the Milky Way – Andromeda system and for the first time explore the fate of the two supermassive black holes (SMBHs) that are located at their centers. We investigated how the uncertainties on the relative motion of the two galaxies, linked with the initial velocities and the density of the diffuse environment in which they move, affect the estimate of the time they need to merge and form “Milkomeda”. After the galaxy merger, we follow the evolution of their two SMBHs up to their close pairing and fusion. Upon the fiducial set of parameters, we find that Milky Way and Andromeda will have their closest approach in the next 4.3 Gyr and merge over a span of 10 Gyr. Although the time of the first encounter is consistent with other predictions, we find that the merger occurs later than previously estimated. We also show that the two SMBHs will spiral in the inner region of Milkomeda and coalesce in less than 16.6 Myr after the merger of the two galaxies. Finally, we evaluate the gravitational-wave emission caused by the inspiral of the SMBHs, and we discuss the detectability of similar SMBH mergers in the nearby Universe (z ≤ 2) through next-generation gravitational-wave detectors.

scholarly journals The origin of the elements and other implications of gravitational wave detection for nuclear physics

4open ◽  
2020 ◽  
Vol 3 ◽  
pp. 14
Author(s):  
David Lunney
Keyword(s):  
Neutron Star ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Nuclear Physics ◽  
Gamma Ray ◽  
Binding Energies ◽  
Historical Event ◽  
Essential Contribution ◽  
Optical Astronomy

The neutron-star collision revealed by the event GW170817 gave us a first glimpse of a possible birthplace of most of our heavy elements. The multi-messenger nature of this historical event combined gravitational waves, a gamma-ray burst and optical astronomy of a “kilonova”, bringing the first observations of rapid neutron capture (r process) nucleosynthesis after 60 years of speculation. Modeling the r process requires a prodigious amount of nuclear-physics ingredients: practically all the quantum state and interaction properties of virtually all neutron-rich nuclides, many of which may never be produced in the laboratory! Another essential contribution of nuclear physics to neutron stars (and their eventual coalescence) is the equation of state (EoS) that defines their structure and composition. The EoS, combined with the knowledge of nuclear binding energies, determines the elemental profile of the outer crust of a neutron star and the relationship between its radius and mass. In addition, the EoS determines the form of the gravitational wave signal. This article combines a tutorial presentation and bibliography with recent results that link nuclear mass spectrometry to gravitational waves via neutron stars.

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.

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 Pulsar Identification of Background Spectra of LIGO Data

2018 ◽  
Vol 1 (2) ◽  
Keyword(s):  
Black Holes ◽  
Exact Solution ◽  
General Relativity ◽  
Time Delay ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Compact Objects ◽  
Gravitational Redshift ◽  
Wave Spectra

By choosing the metric (called physical metric) in general relativity as the exact solution to the Einstein equation that fits the time delay data, one can determine the size and gravitational redshift on the surface of compact objects (neutron stars and black holes). The author shows that the physical metric is invariant by rotation. As a result, the frequencies of gravitational waves from pulsars are represented as n * f / for pulsar frequency f and harmonics n. Based on this result, the author has identified potential pulsar candidates with gravitational wave spectra. This result will be critical in the study of gravitational redshift of compact objects.

scholarly journals Gravitational waves from mountains in newly born millisecond magnetars

2021 ◽  
Vol 502 (4) ◽  
pp. 4680-4688
Author(s):  
Ankan Sur ◽  
Brynmor Haskell
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Massive Star ◽  
Gamma Ray ◽  
Dipole Radiation ◽  
X Ray ◽  
Binary Neutron Star ◽  
Spin Period ◽  
Lower Maximum ◽  
Wave Emission

ABSTRACT In this paper, we study the spin-evolution and gravitational-wave luminosity of a newly born millisecond magnetar, formed either after the collapse of a massive star or after the merger of two neutron stars. In both cases, we consider the effect of fallback accretion; and consider the evolution of the system due to the different torques acting on the star, namely the spin-up torque due to accretion and spin-down torques due to magnetic dipole radiation, neutrino emission, and gravitational-wave emission linked to the formation of a ‘mountain’ on the accretion poles. Initially, the spin period is mostly affected by the dipole radiation, but at later times, accretion spin the star up rapidly. We find that a magnetar formed after the collapse of a massive star can accrete up to 1 M⊙, and survive on the order of 50 s before collapsing to a black hole. The gravitational-wave strain, for an object located at 1 Mpc, is hc ∼ 10−23 at kHz frequencies, making this a potential target for next-generation ground-based detectors. A magnetar formed after a binary neutron star merger, on the other hand, accretes at the most 0.2 M⊙ and emits gravitational waves with a lower maximum strain of the order of hc ∼ 10−24, but also survives for much longer times, and may possibly be associated with the X-ray plateau observed in the light curve of a number of short gamma-ray burst.

Tidal deformation of quantum black holes

2021 ◽  
pp. 2142011
Author(s):  
Ram Brustein ◽  
Yotam Sherf
Keyword(s):  
Black Holes ◽  
Perturbation Theory ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Excited Level ◽  
Love Number ◽  
Standard Time ◽  
Love Numbers ◽  
Classical Black Holes ◽  
Quantum Perturbation Theory

The response of a gravitating object to an external tidal field is encoded in its Love numbers, which identically vanish for classical black holes (BHs). Here we show, using standard time-independent quantum perturbation theory, that for a quantum BH, generically, the Love numbers are nonvanishing and negative. We calculate the quadrupolar electric quantum Love number of slowly rotating BHs and show that it depends most strongly on the first excited level of the quantum BH. Finally, we discuss the detectability of the quadrupolar quantum Love number in future precision gravitational-wave observations and show that, under favourable circumstances, its magnitude is large enough to imprint an observable signature on the gravitational waves emitted during the inspiral. Phase of two moderately spinning BHs.

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