Journal articles on the topic 'Black hole waves'
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1
Qiu, Xinrui, and Siyuan Xiang. "Black Hole Formation and Gravitational Waves Generation." Highlights in Science, Engineering and Technology 38 (March 16, 2023): 659–64. http://dx.doi.org/10.54097/hset.v38i.5919.
Abstract:
In the present day, black holes have recently attracted a variety of attention. Black holes and gravitational waves were studied more than 100 years ago. From theoretical reasoning and formula derivation to detector observation, people never stop to explore these curious things. This paper mainly describes the essential information and principle of black holes, and gravitational waves, as well as the basic operation principle of LIGO detectors. The basic definition of gravitational wave and several sources of the gravitational wave is discussed in this paper. According to the analysis, the properties of waves can be used in detecting gravitational waves, as well as more hidden matter. In 1915, Einstein proposed the general theory of relativity, which foresaw the existence of black holes but did not believe that black holes were real. In the 1960s, American scientist John Wheeler first named this incredible celestial body black hole. The search for gravitational waves has had a profound impact on people. With gravitational waves, people can discover an unknown matter which can be studied and benefit humankind. These results shed light on guiding further exploration of dark energy, matters, and more black hole observations.
2
Adamcewicz, Christian, Shanika Galaudage, Paul D. Lasky, and Eric Thrane. "Which Black Hole Is Spinning? Probing the Origin of Black Hole Spin with Gravitational Waves." Astrophysical Journal Letters 964, no. 1 (March 1, 2024): L6. http://dx.doi.org/10.3847/2041-8213/ad2df2.
Abstract:
Abstract Theoretical studies of angular momentum transport suggest that isolated stellar-mass black holes are born with negligible dimensionless spin magnitudes χ ≲ 0.01. However, recent gravitational-wave observations indicate ≳40% of binary black hole systems contain at least one black hole with a nonnegligible spin magnitude. One explanation is that the firstborn black hole spins up the stellar core of what will become the second-born black hole through tidal interactions. Typically, the second-born black hole is the “secondary” (less massive) black hole though it may become the “primary” (more massive) black hole through a process known as mass-ratio reversal. We investigate this hypothesis by analyzing data from the third gravitational-wave transient catalog using a “single-spin” framework in which only one black hole may spin in any given binary. Given this assumption, we show that at least 28% (90% credibility) of the LIGO–Virgo–KAGRA binaries contain a primary with significant spin, possibly indicative of mass-ratio reversal. We find no evidence for binaries that contain a secondary with significant spin. However, the single-spin framework is moderately disfavored (natural log Bayes factor ln B = 3.1 ) when compared to a model that allows both black holes to spin. If future studies can firmly establish that most merging binaries contain two spinning black holes, it may call into question our understanding of formation mechanisms for binary black holes or the efficiency of angular momentum transport in black hole progenitors.
3
Khan, Muhammad Atif, Farhad Ali, Nahid Fatima, and Mohamed Abd El-Moneam. "Particles Dynamics in Schwarzschild like Black Hole with Time Contracting Horizon." Axioms 12, no. 1 (December 27, 2022): 34. http://dx.doi.org/10.3390/axioms12010034.
Abstract:
The black holes radiate their mass and energy in the form of gravitational waves and Hawking-radiation, which lead to a decrease in the mass and energy of the black holes. During the formation of gravitational waves and Hawking radiation, the mass and energy of black holes reduce continuously with the passage of time t. For this reason the metric tensor of the black hole should depends on time t. In this work, a time-dependent term is introduced in the horizon of black hole without losing its symmetry structure by using the approximate Noether symmetry equation. The time-dependent term affects the effective potential, effective force, and all the dynamic features of the black hole. They are discussed for neutral and charged particles. Profiles of the escape velocity of colliding particles are also taken into consideration. Lyapunov exponent is used to check the stability of the orbits of the black hole. Hawking temperature, Bekenstein entropy, Komar energy, and specific energy at horizon of the black hole are discussed in this scenario.
4
Broekgaarden, Floor S., Simon Stevenson, and Eric Thrane. "Signatures of Mass Ratio Reversal in Gravitational Waves from Merging Binary Black Holes." Astrophysical Journal 938, no. 1 (October 1, 2022): 45. http://dx.doi.org/10.3847/1538-4357/ac8879.
Abstract:
Abstract The spins of merging binary black holes offer insights into their formation history. Recently it has been argued that in the isolated binary evolution of two massive stars the firstborn black hole is slowly rotating, while the progenitor of the second-born black hole can be tidally spun up if the binary is tight enough. Naively, one might therefore expect that only the less massive black hole in merging binaries exhibits nonnegligible spin. However, if the mass ratio of the binary is “reversed” (typically during the first mass transfer episode), it is possible for the tidally spun up second-born to become the more massive black hole. We study the properties of such mass ratio reversed binary black hole mergers using a large set of 560 population synthesis models. We find that the more massive black hole is formed second in ≳70% of binary black holes observable by LIGO, Virgo, and KAGRA for most model variations we consider, with typical total masses ≳20 M ⊙ and mass ratios q = m 2/m 1 ∼ 0.7 (where m 1 > m 2). The formation history of these systems typically involves only stable mass transfer episodes. The second-born black hole has nonnegligible spin (χ > 0.05) in up to 25% of binary black holes, with among those the more (less) massive black hole is spinning in 0%–80% (20%–100%) of the cases, varying greatly in our models. We discuss our models in the context of several observed gravitational-wave events and the observed mass ratio—effective spin correlation.
5
Abe, Junya, and Masayoshi Yokosawa. "11.10. The propagation of fast magnetoacoustic waves near a rotating black hole." Symposium - International Astronomical Union 184 (1998): 475–76. http://dx.doi.org/10.1017/s0074180900085648.
Abstract:
We belive that Active Galactic Nucleis(AGNs) have one or a few black holes in the center and get the activity from the binding energy of the matter falling into the black hole or(and) the rotational energy of the black hole. Since the sources of their energy exist near the black hole, the energy have to be carried from the vincity of black hole to a distance by some ways. As one of the way, we study the propagation of the waves (ex. The case of the light waves, Hanni 1977, and of sound wave, Takahashi et al. 1990). We investigated the propagation of fast magnetoacoustic wave. We belive the collimation of jet are caused by magnetic field. Further more, we think that the waves can extract the rotational energy of the black hole. This process is the version of wave of Penrose process(Penrose 1968), and is called the super radiant scattering.
6
Eroshenko, Yury, and Viktor Stasenko. "Gravitational Waves from the Merger of Two Primordial Black Hole Clusters." Symmetry 15, no. 3 (March 3, 2023): 637. http://dx.doi.org/10.3390/sym15030637.
Abstract:
The orbital evolution of a binary system consisting of two primordial black hole clusters is investigated. Such clusters are predicted in some theoretical models with broken symmetry in the inflation Lagrangian. A cluster consists of the most massive central black hole surrounded by many smaller black holes. Similar to single primordial black holes, clusters can form gravitationally bounded pairs and merge during their orbital evolution. The replacement of single black holes by such clusters significantly changes the entire merger process and the final rate of gravitational wave bursts in some parameter ranges (with sufficiently large cluster radii). A new important factor is the tidal gravitational interaction of the clusters. It leads to an additional dissipation of the orbital energy, which is transferred into the internal energy of the clusters or carried away by black holes flying out of the clusters. Comparison with the data of gravitational-wave telescopes allows one to constrain the fractions of primordial black holes in clusters, depending on their mass and compactness. Even the primordial black hole fraction in the composition of dark matter ≃1 turns out to be compatible with LIGO/Virgo observational data, if the black holes are in clusters.
7
Hong, Jongsuk, Abbas Askar, Mirek Giersz, Arkadiusz Hypki, and Suk-Jin Yoon. "mocca-survey Database I: Binary black hole mergers from globular clusters with intermediate mass black holes." Monthly Notices of the Royal Astronomical Society 498, no. 3 (September 4, 2020): 4287–94. http://dx.doi.org/10.1093/mnras/staa2677.
Abstract:
ABSTRACT The dynamical formation of black hole binaries in globular clusters that merge due to gravitational waves occurs more frequently in higher stellar density. Meanwhile, the probability to form intermediate mass black holes (IMBHs) also increases with the density. To explore the impact of the formation and growth of IMBHs on the population of stellar mass black hole binaries from globular clusters, we analyse the existing large survey of Monte Carlo globular cluster simulation data (mocca-survey Database I). We show that the number of binary black hole mergers agrees with the prediction based on clusters’ initial properties when the IMBH mass is not massive enough or the IMBH seed forms at a later time. However, binary black hole formation and subsequent merger events are significantly reduced compared to the prediction when the present-day IMBH mass is more massive than ${\sim}10^4\, \rm M_{\odot }$ or the present-day IMBH mass exceeds about 1 per cent of cluster’s initial total mass. By examining the maximum black hole mass in the system at the moment of black hole binary escaping, we find that ∼90 per cent of the merging binary black holes escape before the formation and growth of the IMBH. Furthermore, large fraction of stellar mass black holes are merged into the IMBH or escape as single black holes from globular clusters in cases of massive IMBHs, which can lead to the significant underpopulation of binary black holes merging with gravitational waves by a factor of 2 depending on the clusters’ initial distributions.
8
Palchoudhury, Sankar. "About Black Holes." International Journal of Fundamental Physical Sciences 11, no. 1 (March 2021): 6–9. http://dx.doi.org/10.14331/ijfps.2021.330144.
Abstract:
All kinds of waves occur for the disturbances in the quiet gravitational field. Different waves powered differently and propagated in the gravitational field. A black hole is the higher GFI (Gravitational Field Intensity) area. The rays do not possess, coming from a distant source when pass by the black holes, adequate strength to disturb in the higher GFI area of the black holes. Naturally, the rays take on a curve path as the provision in a circular area depends on the radius (distance), keeping distance according to the lower GFI area around the black holes’ centre.
9
Ha, Yuan K. "Weighing the black hole via quasi-local energy." Modern Physics Letters A 32, no. 24 (July 10, 2017): 1730021. http://dx.doi.org/10.1142/s021773231730021x.
Abstract:
We set to weigh the black holes at their event horizons in various spacetimes and obtain masses which are substantially higher than their asymptotic values. In each case, the horizon mass of a Schwarzschild, Reissner–Nordström, or Kerr black hole is found to be twice the irreducible mass observed at infinity. The irreducible mass does not contain electrostatic or rotational energy, leading to the inescapable conclusion that particles with electric charges and spins cannot exist inside a black hole. This is proposed as the External Energy Paradigm. A higher mass at the event horizon and its neighborhood is obligatory for the release of gravitational waves in binary black hole merging. We describe how these horizon mass values are obtained in the quasi-local energy approach and applied to the black holes of the first gravitational waves GW150914.
10
Mitra, Ayan, Pritam Chattopadhyay, Goutam Paul, and Vasilios Zarikas. "Binary Black Hole Information Loss Paradox and Future Prospects." Entropy 22, no. 12 (December 8, 2020): 1387. http://dx.doi.org/10.3390/e22121387.
Abstract:
Various techniques to tackle the black hole information paradox have been proposed. A new way out to tackle the paradox is via the use of a pseudo-density operator. This approach has successfully dealt with the problem with a two-qubit entangle system for a single black hole. In this paper, we present the interaction with a binary black hole system by using an arrangement of the three-qubit system of Greenberger–Horne–Zeilinger (GHZ) state. We show that our results are in excellent agreement with the theoretical value. We have also studied the interaction between the two black holes by considering the correlation between the qubits in the binary black hole system. The results depict a complete agreement with the proposed model. In addition to the verification, we also propose how modern detection of gravitational waves can be used on our optical setup as an input source, thus bridging the gap with the gravitational wave’s observational resources in terms of studying black hole properties with respect to quantum information and entanglement.
11
MYUNG, Y. S., N. J. KIM, and H. W. LEE. "6-D BLACK STRING AS A MODEL OF THE AdS/CFT CORRESPONDENCE." Modern Physics Letters A 14, no. 08n09 (March 21, 1999): 575–83. http://dx.doi.org/10.1142/s0217732399000638.
Abstract:
We discuss the entropy for the extremal BTZ black hole and the extremal EBTZ black hole. The EBTZ black hole means the BTZ black hole embedded in a five-dimensional (5-D) black hole. The six-dimensional (6-D) black string with traveling waves is introduced as a concrete model for realizing the AdS/CFT correspondence. The traveling waves carry the momentum distribution p(u) which plays an important role in counting the entropy and establishing the correspondence. It turns out that the EBTZ black hole is consistent with the AdS/CFT correspondence.
12
Shibata, K., S. Koide, T. Kudoh, and S. Aoki. "Jets from Black Hole Magnetospheres." Symposium - International Astronomical Union 195 (2000): 265–72. http://dx.doi.org/10.1017/s0074180900163028.
Abstract:
Recent general-relativistic MHD simulations of jets ejected from black-hole magnetospheres (for both Schwarzschild and Kerr holes) have revealed that (1) strong shock waves are formed in the accretion flow inside 3rs, (2) jets show two-layered shell structure consisting of a gas-pressure driven jet and a magnetically driven jet, the former being accelerated from a high-pressure region heated by strong shocks, and (3) in the case of a Kerr hole, magnetically driven jets are produced from the ergosphere by the effect of frame dragging.
13
Zhong, Zimu. "Principle and State-of-art Observation Scenarios of Black Holes." Highlights in Science, Engineering and Technology 72 (December 15, 2023): 129–35. http://dx.doi.org/10.54097/p5450f83.
Abstract:
Tracing back to the 17th century, the concept of black holes emerged as "dark stars," celestial bodies with gravitational pull surpassing the speed of light. Schwarzschild's solution to Einstein's equations in 1916 introduced the concept of a singularity and the Schwarzschild radius, defining black holes as objects compressed within this boundary. Two main classification methods for black holes based on mass and charge/angular momentum are discussed’. The study explores the principles of detection: gravitational waves, generated by events like black hole mergers, and gravitational lensing, where immense mass bends space and time, distorting light from distant objects. Facilities such as LIGO, Virgo, and KAGRA are introduced, showcasing their contributions in detecting gravitational waves. Optical telescopes like the Hubble Space Telescope and the Event Horizon Telescope play a vital role in visualizing black holes. Recent results include numerous successful black hole detections, testing the validity of General Relativity, and providing precise information on black hole masses and locations. While limitations in sensitivity and resolution persist, the future outlook is promising. Advancements in observatory technology, third-generation gravitational wave detectors, and multi-messenger astronomy collaborations will deepen our understanding of black holes and their role in the cosmos, fueling ongoing exploration of these enigmatic cosmic entities.
14
Adhikary, Subhrangshu, and Saikat Banerjee. "Binary Black Hole Automated Identification by Agglomerative Clustering based on Gravitational Waves." Journal of Physics: Conference Series 2089, no. 1 (November 1, 2021): 012027. http://dx.doi.org/10.1088/1742-6596/2089/1/012027.
Abstract:
Abstract The General Theory of Relativity, proposed by Albert Einstein theoretically predicted that very large accelerating mass creates ripples in spacetime which is the strongest for merging binary black hole system and the ripples can travel billions of light-years and these ripples are called Gravitational Waves. By the time these waves reach Earth, they become very faint and can’t be detected with regular methods. For this, LIGO has created specialized detectors based on the laser interference principle to detect strains caused by gravitational waves in e-19 scale. GW190521 is a gravitational wave event recorded on 21 May 2019 at 03:02:29 UTC and caused by the merger of two black holes of 85M© and 66 M© whose progenitor was the largest ever recorded. Throughout literature, very few amounts of autonomous black hole identification models have been made because of limited data availability. This experiment proposes methods for autonomous identification of black holes by using an unsupervised machine learning algorithm called Agglomerative Clustering with very little data to train which can adapt quickly to gravitational wave events. The model could be easily deployed near laser interferometric observatories for autonomous black hole identification with minimal effort.
15
Zhou, Shiwei, and Kui Xiao. "Hawking radiation of analogous acoustic black holes." Modern Physics Letters A 35, no. 28 (July 30, 2020): 2050236. http://dx.doi.org/10.1142/s0217732320502363.
Abstract:
Propagation of sound waves in a flowing fluid can be viewed as a minimally coupled massless scalar field propagating in curved spacetime. The analogue Hawking radiation from a spherically symmetric acoustic black hole and a (2 + 1)-dimensional rotating acoustic black hole are investigated respectively in Damour–Ruffini’s method. The emission rate and Hawking temperature are obtained, which are related to acoustic black holes parameter.
16
Callister, Thomas A., Simona J. Miller, Katerina Chatziioannou, and Will M. Farr. "No Evidence that the Majority of Black Holes in Binaries Have Zero Spin." Astrophysical Journal Letters 937, no. 1 (September 1, 2022): L13. http://dx.doi.org/10.3847/2041-8213/ac847e.
Abstract:
Abstract The spin properties of merging black holes observed with gravitational waves can offer novel information about the origin of these systems. The magnitudes and orientations of black hole spins offer a record of binaries’ evolutionary history, encoding information about massive stellar evolution and the astrophysical environments in which binary black holes are assembled. Recent analyses of the binary black hole population have yielded conflicting portraits of the black hole spin distribution. Some works suggest that black hole spins are small but nonzero and exhibit a wide range of misalignment angles relative to binaries’ orbital angular momenta. Other works conclude that the majority of black holes are nonspinning while the remainder are rapidly rotating and primarily aligned with their orbits. We revisit these conflicting conclusions, employing a variety of complementary methods to measure the distribution of spin magnitudes and orientations among binary black hole mergers. We find that the existence of a subpopulation of black holes with vanishing spins is not required by current data. Should such a subpopulation exist, we conclude that it must contain ≲60% of binaries. Additionally, we find evidence for significant spin–orbit misalignment among the binary black hole population, with some systems exhibiting misalignment angles greater than 90°, and see no evidence for an approximately spin-aligned subpopulation.
17
Okuda, T., V. Teresi, and D. Molteni. "QPOs expected in rotating accretion flows around a supermassive black hole." Proceedings of the International Astronomical Union 2, S238 (August 2006): 423–24. http://dx.doi.org/10.1017/s1743921307005765.
Abstract:
AbstractIt is well known that rotating inviscid accretion flows with adequate injection parameters around black holes could form shock waves close to the black holes, after the flow passes through the outer sonic point and can be virtually stopped by the centrifugal force. We numerically examine such shock waves in 2D accretion flows with 10−5 to 106 Eddington critical accretion rates around a supermassive black hole with 106M⊙. As the results, the luminosities show QPO phenomena with modulations of a factor 2–3 and with quasi-periods of a few to several hours.
18
HUBENY, VERONIKA E., and MUKUND RANGAMANI. "HORIZONS AND PLANE WAVES: A REVIEW." Modern Physics Letters A 18, no. 38 (December 14, 2003): 2699–711. http://dx.doi.org/10.1142/s0217732303012428.
Abstract:
We review the attempts to construct black hole/string solutions in asymptotically plane wave spacetimes. First, we demonstrate that geometries admitting a covariantly constant null Killing vector cannot admit event horizons, which implies that pp-waves cannot describe black holes. However, relaxing the symmetry requirements allows us to generate solutions which do possess regular event horizons while retaining the requisite asymptotic properties. In particular, we present two solution generating techniques and use them to construct asymptotically plane wave black string/brane geometries.
19
Zhang, Jiahao. "Exploring black hole-neutron star binary merger by detecting gravitational waves." Theoretical and Natural Science 13, no. 1 (November 30, 2023): 59–64. http://dx.doi.org/10.54254/2753-8818/13/20240790.
Abstract:
Unlike black hole binary merger, the merger between a neutron star and a black hole will produce an abundant number of gravitational waves and electromagnetic waves. Using this information, scientists can easily find many properties of the universe and test the general relativity and some other gravitational theories. The detection of the gravitational wave from source is essential to develop the current knowledge of the gravitational force. From last century, scientists were trying to detect the gravitational waves, and as the time passes, the method of detection has already developed from on land detector to space detector in order to take more precise readings. This paper provides some basic information of the neutron star and the black hole, together with the formation of the binary neutron star-black hole system. The relationship between the neutron star and black hole is explained in this paper. The knowledge of the current methods of detecting gravitational waves is also provided and the paper specifically elaborated the space laser interferometry.
20
Vachaspati, Tanmay. "Gravitational waves, gamma ray bursts, and black stars." International Journal of Modern Physics D 25, no. 12 (October 2016): 1644025. http://dx.doi.org/10.1142/s0218271816440259.
Abstract:
Stars that are collapsing towards forming a black hole but appear frozen near their Schwarzschild horizon are termed “black stars”. The collision of two black stars leads to gravitational radiation during the merging phase followed by a delayed gamma ray burst during coalescence. The recent observation of gravitational waves by LIGO, followed by a possible gamma ray counterpart by Fermi, suggests that the source may have been a merger of two black stars with profound implications for quantum gravity and the nature of black holes.
21
Taheri, Mohammad Ali. "The Cosmic Black Hole." Scientific Journal of Cosmointel 3, TC2EN (April 24, 2024): 12–37. http://dx.doi.org/10.61450/joci.v3itc2en.176.
Abstract:
Concurrent with advancements in cosmology, various theories have been proposed about the origin of the universe or its ultimate fate. These theories include the Steady State Theory, Oscillating Universe Theory or Cyclic model, Multiverse Theory, String Theory/M-Theory, Quantum Gravity or Loop Quantum Cosmology, The Big Bang Theory, Inflationary Universe Theory, and the No-Boundary Proposal. Among these, the Big Bang theory has been widely accepted by most scientists, with the Inflation theory serving as its complementary addition. On the other hand, theories such as the big rip, flat universe, and big crunch have also addressed the ultimate fate of the cosmos. However, T-Consciousness Cosmology presents a new hypothesis to explain how the universe was born from a black hole named the ‘Cosmic Black Hole,’ or the initial seed of the universe. This hypothesis not only addresses how this particular type of black hole forms, contingent on the reversion of the cosmos according to the Spherical Cosmos model but also details its fundamental differences from known black holes, referred to as “intra-cosmic black holes.” The reversion of the cosmos in the ‘Spherical Cosmos Model,’ is described through a mechanism known as space Rebound, which is distinct from the Big Crunch. The Terminal Edge of the cosmos is defined as the maximum radius at which space mesh is capable of rebound during the universe's volume increase. In the process of the rebound of space to its ultimate extent, objects within the cosmos face complete disintegration and transform into waves called absolute waves. Due to the inherent rotation of the cosmos and its reversion from the Terminal Edge, these waves collide and create gravitational centers in the central regions of the spherical cosmos, forming new types of matter known as light-dark matter, dark-dark matter, and thermal matter. Each of these mentioned materials represents a new type of matter introduced by T-Consciousness Cosmology. Additionally, according to this model, the cosmos contracts into a very tiny point with a final quench, where all types of matter and fundamental forces unite, forming a new type of absolute matter called ‘Taheri Absolute Matter’ (TAM). The spherical cosmos model also divides time into various types: ‘Longitudinal’ and ‘Transverse,’ and unlike the theory of relativity, where time is considered a dimension, it classifies it as one of the types of transverse time introduced as an entropic force. In essence, this type of force (time) acts against the force of gravity and, by disintegrating all types of objects from fundamental to large scale, acts as an agent of stress or tension release from the space mesh.
22
Belczynski, K., and S. Banerjee. "Formation of low-spinning 100 M⊙ black holes." Astronomy & Astrophysics 640 (August 2020): L20. http://dx.doi.org/10.1051/0004-6361/202038427.
Abstract:
Aims. It is speculated that a merger of two massive stellar-origin black holes in a dense stellar environment may lead to the formation of a massive black hole in the pair-instability mass gap (∼50−135 M⊙). Such a merger-formed black hole is expected to typically have a high spin (a ∼ 0.7). If such a massive black hole acquires another black hole it may lead to another merger detectable by LIGO/Virgo in gravitational waves. Acquiring a companion may be hindered by gravitational-wave kick/recoil, which accompanies the first merger and may quickly remove the massive black hole from its parent globular or nuclear cluster. We test whether it is possible for a massive merger-formed black hole in the pair-instability gap to be retained in its parent cluster and have low spin. Such a black hole would be indistinguishable from a primordial black hole. Methods. We employed results from numerical relativity calculations of black hole mergers to explore the range of gravitational-wave recoil velocities for various combinations of merging black hole masses and spins. We compared merger-formed massive black hole speeds with typical escape velocities from globular and nuclear clusters. Results. We show that a globular cluster is highly unlikely to form and retain a ∼100 M⊙ black hole if the spin of the black hole is low (a ≲ 0.3). Massive merger-formed black holes with low spins acquire high recoil speeds (≳ 200 km s−1) from gravitational-wave kick during formation that exceed typical escape speeds from globular clusters (∼ 50 km s−1). However, a very low-spinning (a ∼ 0.1) and massive (∼100 M⊙) black hole could be formed and retained in a galactic nuclear star cluster. Even though such massive merger-formed black holes with such low spins acquire high speeds during formation (∼ 400 km s−1), they may avoid ejection since massive nuclear clusters have high escape velocities (∼ 300−500 km s−1). A future detection of a massive black hole in the pair-instability mass gap with low spin would therefore not be proof of the existence of primordial black holes, which are sometimes claimed to have low spins and arbitrarily high masses.
23
DE OLIVEIRA, H. P., and E. L. RODRIGUES. "BLACK HOLES COLLISION IN GENERAL ROBINSON-TRAUTMAN SPACETIMES: WAVE FORMS AND THE EFFICIENCY OF THE GRAVITATIONAL WAVE EXTRACTION." International Journal of Modern Physics: Conference Series 03 (January 2011): 408–16. http://dx.doi.org/10.1142/s2010194511000924.
Abstract:
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.
24
Mirabel, I. F. "Black holes formed by direct collapse: observational evidences." Proceedings of the International Astronomical Union 12, S324 (September 2016): 303–6. http://dx.doi.org/10.1017/s1743921316012904.
Abstract:
AbstractBinary black holes as the recently detected sources of gravitational waves can be formed from massive stellar binaries in the field or by dynamical interactions in clusters of high stellar density, if the black holes are the remnants of massive stars that collapsed without natal kicks that would disrupt the binary system or eject the black holes from the cluster before binary black hole formation. Here are summarized and discussed the kinematics in three dimensions of space of five Galactic black hole X-ray binaries. For Cygnus X-1 and GRS 1915+105 it is found that the black holes of ~15 M⊙ and ~10 M⊙ in these sources were formed in situ, without energetic kicks. These observations suggest that binary black holes with components of ~10 M⊙ may have been prolifically produced in the universe.
25
Raidal, Martti, Ville Vaskonen, and Hardi Veermäe. "Gravitational waves from primordial black hole mergers." Journal of Cosmology and Astroparticle Physics 2017, no. 09 (September 26, 2017): 037. http://dx.doi.org/10.1088/1475-7516/2017/09/037.
26
Roupas, Zacharias, and Demosthenes Kazanas. "Binary black hole growth by gas accretion in stellar clusters." Astronomy & Astrophysics 621 (January 2019): L1. http://dx.doi.org/10.1051/0004-6361/201834609.
Abstract:
We show that binaries of stellar-mass black holes formed inside a young protoglobular cluster, can grow rapidly inside the cluster’s core by accretion of the intracluster gas, before the gas may be depleted from the core. A black hole with mass of the order of eight solar masses can grow to values of the order of thirty five solar masses in accordance with recent gravitational waves signals observed by LIGO. Due to the black hole mass increase, a binary may also harden. The growth of binary black holes in a dense protoglobular cluster through mass accretion indicates a potentially important formation and hardening channel.
27
van den Brand, Jo. "Gravitational Waves: Physics at the Extreme." European Review 26, no. 1 (January 15, 2018): 90–99. http://dx.doi.org/10.1017/s1062798717000801.
Abstract:
Last year, the LIGO Scientific Collaboration and the Virgo Collaboration announced the first detection of a gravitational wave. A century after the fundamental predictions of Einstein, the first direct observation of a binary black hole system merging to form a single black hole was made. The observations provide unique access to the properties of spacetime at extreme curvatures: the strong-field and high-velocity regime. It allows unprecedented tests of general relativity for the nonlinear dynamics of highly disturbed black holes. LIGO and Virgo realized a global interferometer network, and more detections were made, including a signal from a binary neutron star merger. The scientific impact of the various detections will be explained. In addition, key technological aspects will be addressed, such as the interferometric detection principle, optics, as well as sensors and actuators. Attention is paid to Advanced Virgo, the European detector near Pisa, which came online in 2017. We end with a discussion of the largest challenges in the field, including plans for the Einstein Telescope, a large underground observatory for gravitational-wave science.
28
Macedo, Caio F. B., Luís C. B. Crispino, and Ednilton S. de Oliveira. "Scalar waves in regular Bardeen black holes: Scattering, absorption and quasinormal modes." International Journal of Modern Physics D 25, no. 09 (August 2016): 1641008. http://dx.doi.org/10.1142/s021827181641008x.
Abstract:
We discuss the phenomenology of massless scalar fields around a regular Bardeen black hole, namely absorption cross-section, scattering cross-section and quasinormal modes. We compare the Bardeen and Reissner–Nordström black holes, showing limiting cases for which their properties are similar.
29
Zevin, Michael, and Daniel E. Holz. "Avoiding a Cluster Catastrophe: Retention Efficiency and the Binary Black Hole Mass Spectrum." Astrophysical Journal Letters 935, no. 1 (August 1, 2022): L20. http://dx.doi.org/10.3847/2041-8213/ac853d.
Abstract:
Abstract The population of binary black hole mergers identified through gravitational waves has uncovered unexpected features in the intrinsic properties of black holes in the universe. One particularly surprising and exciting result is the possible existence of black holes in the pair-instability mass gap, ∼50–120 M ⊙. Dense stellar environments can populate this region of mass space through hierarchical mergers, with the retention efficiency of black hole merger products strongly dependent on the escape velocity of the host environment. We use simple toy models to represent hierarchical merger scenarios in various dynamical environments. We find that hierarchical mergers in environments with high escape velocities (≳300 km s−1) are efficiently retained. If such environments dominate the binary black hole merger rate, this would lead to an abundance of high-mass mergers that is potentially incompatible with the empirical mass spectrum from the current catalog of binary black hole mergers. Models that efficiently generate hierarchical mergers, and contribute significantly to the observed population, must therefore be tuned to avoid a “cluster catastrophe” of overproducing binary black hole mergers within and above the pair-instability mass gap.
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Backerra, Anna C. M. "The Twin Physics Interpretation of Gravitational Waves." Applied Physics Research 10, no. 1 (January 30, 2017): 23. http://dx.doi.org/10.5539/apr.v10n1p23.
Abstract:
Gravitational waves may originate in two approaching black holes, circling around each other until they merge together. This phenomenon is considered by using twin physics, based upon a complementary mathematical language, after fitting Einstein’s idea about the relationship between time and space into it. According to the description obtained, the two black holes are annihilated as soon as they touch each other; only after a rearrangement of the constituent Heisenberg-units, these being units of potential energy, one new black hole is generated. During this rearrangement, a pair of oppositely charged particles appears, which is considered to be the birth of electromagnetism. This occurs during a period of time which is principally too short to measure, which seems to be the reason for the apparent merging of the black holes. The expectation is that extraordinarily large signals will be repeatedly received, related to a chain of annihilations of black solid particle pairs and subsequent generations of single black solid particles. We suppose that these signals represent gravitational waves.
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AREF’EVA, I. YA, I. V. VOLOVICH, and K. S. VISWANATHAN. "ON BLACK HOLE CREATION IN PLANCKIAN ENERGY SCATTERING." International Journal of Modern Physics D 05, no. 06 (December 1996): 707–21. http://dx.doi.org/10.1142/s0218271896000448.
Abstract:
In a series of papers Amati, Ciafaloni and Veneziano and ’t Hooft conjectured that black holes occur in the collision of two light particles at planckian energies. In this talk based on [10] we discuss a possible scenario for such a process by using the Chandrasekhar-Ferrari-Xanthopoulos duality between the Kerr black hole solution and colliding plane gravitational waves.
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Beradze, Revaz, and Merab Gogberashvili. "Gravitational Waves from Mirror World." Physics 1, no. 1 (March 27, 2019): 67–75. http://dx.doi.org/10.3390/physics1010007.
Abstract:
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.
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Tagoshi, Hideyuki, Shuhei Mano, and Eiichi Takasugi. "Post-Newtonian Expansion of Gravitational Waves from a Particle in Circular Orbits around a Rotating Black Hole: Effects of Black Hole Absorption." Symposium - International Astronomical Union 183 (1999): 163. http://dx.doi.org/10.1017/s0074180900132437.
Abstract:
Coalescing compact binaries are the most promising candidates for detection by near-future, ground based laser interferometric detectors. It is very important to investigate detailed wave forms from coalescing compact binaries. When one (or two) of the stars is a black hole, some of those waves are absorbed by the black hole. Here, we consider a case when a test particle moves circular orbit on the equatorial plane around a Kerr black hole, and calculate the the energy absorption rate by the black hole. We adopt an analytic techniques for the Teukolsky equation which was found by Mano, Suzuki, and Takasugi (1996). We calculated the energy absorption rate to O((v/c)13) beyond the Newtonian-quadrupole formula of gravitational waves radiated to infinity, assuming v/c ≪ 1. Here v is the velocity of the particle. We find that, when a black hole is rotating, the black hole absorption appear at O((v/c)5) beyond the Newtonian-quadrapole formula. These effects become more important as the mass of the black hole becomes larger. We also found that the black hole absorption is more important when a particle moves to the same direction of the black hole rotation. All the details of this paper is presented in Tagoshi et al. (1997).
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You, Zhi-Qiang, Zu-Cheng Chen, Lang Liu, Zhu Yi, Xiao-Jin Liu, You Wu, and Yi Gong. "Constraints on peculiar velocity distribution of binary black holes using gravitational waves with GWTC-3." Journal of Cosmology and Astroparticle Physics 2024, no. 05 (May 1, 2024): 031. http://dx.doi.org/10.1088/1475-7516/2024/05/031.
Abstract:
Abstract Peculiar velocity encodes rich information about the formation, dynamics, evolution, and merging history of binary black holes. In this work, we employ a hierarchical Bayesian model to infer the peculiar velocity distribution of binary black holes. We use the data from GWTC-3 and assume a Maxwell-Boltzmann distribution for the peculiar velocities, but do not consider the dependence of peculiar velocity on the masses of black hole binaries. The constraint on the peculiar velocity distribution parameter, v 0, is weak and uninformative. However, the determination of peculiar velocity distribution can be significantly improved with next-generation ground-based gravitational wave detectors. For the Einstein Telescope, the relative uncertainty of v 0 will reduce to ∼ 10% using 103 golden binary black hole events. Our statistical approach thus provides a robust and prospective inference for determining the peculiar velocity distribution.
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PORTEGIES ZWART, SIMON F., and STEPHEN L. W. MCMILLAN. "GRAVITATIONAL THERMODYNAMICS AND BLACK-HOLE MERGERS." International Journal of Modern Physics A 15, no. 30 (December 10, 2000): 4871–75. http://dx.doi.org/10.1142/s0217751x00002135.
Abstract:
Black holes become the most massive objects early in the evolution of star clusters. Dynamical relaxation then causes them to sink to the cluster core, where they form binaries which become more tightly bound by superelastic encounters with other cluster members. Ultimately, these binaries are ejected from the cluster. The majority of escaping black-hole binaries have orbital periods short enough and eccentricities high enough that the emission of gravitational waves causes them to coalesce within a few billion years. The rate at which such collisions occur is on the order of 10-7 per year per cubic megaparsec. This implies event rates for gravitational-wave detectors substantially greater than current estimates of the corresponding rates from neutron-star mergers or black-hole mergers stemming from pure binary evolution.
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KARIMOV, R. KH. "GEODESIC ORBITS AND LYAPUNOV EXPONENTS OF FROLOV'S BLACK HOLE." Izvestia Ufimskogo Nauchnogo Tsentra RAN, no. 2 (June 16, 2023): 34–38. http://dx.doi.org/10.31040/2222-8349-2023-0-2-34-38.
Abstract:
Binary black holes maintain unstable orbits at very close distances. In the simplest case of geodesics around a Schwarzschild black hole, the orbits, although unstable, are regular and depend only on the mass. In more complex cases, geodesics may depend on charge, rotation, and other parameters. When perturbed, unstable orbits can become a source of chaos. All unstable orbits, whether regular or chaotic, can be quantified by their Lyapunov exponents. Exponents are important for observations because the phase of gravitational waves can decohere in Lyapunov time. If the time scale of dissipation due to gravitational waves is shorter than the Lyapunov time, the chaos will be damped and practically unobservable. These two time scales can be compared. Lyapunov exponents should be used with caution for several reasons: they are relative and dependent on the coordinate system used, they vary from orbit to orbit, and finally, they can be deceptively diluted by transitional behavior for orbits that pass in and out of unstable regions. The stability of circular geodesic orbits of Frolov's black hole space-time is studied in this work. The influence of the black hole charge and the scale parameter on the stability of geodesic orbits and the Lyapunov exponent is analyzed. It is shown that the region of stable circular orbits increases with the black hole charge Q and the scale parameter ℓ . The largest region of stable circular orbits of Frolov's black hole is reached at Q = M and ℓ = 0.75M.
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Williams, Floyd L. "Exploring a Cold Plasma-2d Black Hole Connection." Advances in Mathematical Physics 2019 (August 19, 2019): 1–11. http://dx.doi.org/10.1155/2019/4810904.
Abstract:
Using a resonance nonlinear Schrödinger equation as a bridge, we explore a direct connection of cold plasma physics to two-dimensional black holes. Namely, we compute and diagonalize a metric attached to the propagation of magnetoacoustic waves in a cold plasma subject to a transverse magnetic field, and we construct an explicit change of variables by which this metric is transformed exactly to a Jackiw-Teitelboim black hole metric.
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DÖNMEZ, ORHAN. "DYNAMICAL EVOLUTION OF ROTATING ACCRETION USING DIFFERENT BOUNDARY CONDITIONS: STATE AFTER STABLE ACCRETION DISK CREATED." International Journal of Modern Physics D 16, no. 10 (October 2007): 1541–53. http://dx.doi.org/10.1142/s0218271807010912.
Abstract:
The 2D time-dependent solution of the thin and stable accretion disk with two-armed spiral shock waves in a closed binary system have been presented on the equatorial plane around the Schwarzschild black hole in Donmez (2004).2 The subject of this paper is to study the influence of two different boundary conditions, far away from a black hole called the outer boundary, on an accretion disk around the black hole during the time evolution. We have started with a stable accretion disk after the point where two-armed spiral shock waves were created (Donmez, 2004).2 The initial data which is also called the freezing boundary is used as a first boundary condition. As a second one, we use the outflow boundary condition. In both cases, the accretion disk is created and gases on the disk made closed trajectories. As a stable tori close to the black hole is created by using the first boundary, freezing condition, which has a ~10M radius where M is the mass of black hole, and the other boundary, outflow, creates stable two-armed spiral shock waves. The last stable circular orbit around the Schwarzschild black hole for this type of accretion disk is located around 11M in the case of the freezing boundary condition. The results of these simulations show that the tori and spiral shock waves are created in each case using freezing and the outflow boundary, respectively, and it also suggests that spiral waves are a robust feature of accretion disks in binary systems, and that these spiral shocks can indeed transfer the gravitational energy to the radiation energy observed by different X-ray satellites.
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Xu, Zixuan. "Analysis of the Concepts and Searching for Mini Black Hole." Highlights in Science, Engineering and Technology 72 (December 15, 2023): 736–41. http://dx.doi.org/10.54097/pp6v0440.
Abstract:
With the progression of time, individuals have an increasing desire and interest in the universe, and black holes, as perilous and enigmatic entities within the universe, naturally draw the attention of many individuals seeking to study them. Amongst all types of black holes, the mini black hole is particularly mysterious, and it remains unknown whether it even exists. This study will briefly introduce and integrate the concept of MBHs and their search. In fact, the life expectancy of a mini black hole is divided into four stages, which distinguishes it from other black holes. Ultimately, it will culminate in the production of short gamma ray bursts. Two methods for detecting mini black holes have been identified, one through gravitational waves and the other through Radio and X-Ray Sky. If the existence of MBHs is proven, some of the Universe's puzzles may be solved or explained. The paper's significance lies in its ability to provide a straightforward comprehension of mini black holes for individuals seeking further knowledge on the topic.
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Cao, Jingwen, and Shuai Hu. "The Recent progress and state-of-art detection scenarios for black holes and gravitational waves." Highlights in Science, Engineering and Technology 17 (November 10, 2022): 120–27. http://dx.doi.org/10.54097/hset.v17i.2534.
Abstract:
Gravitational waves, predicted by Einstein within the framework of general relativity, were discovered and confirmed by LIGO in 2015. Based on the detection of gravitational waves, black holes were also confirmed and recorded for the first time. In this article, we provide an overview of the mechanism of gravitational waves generated by black hole mergers, including basic formulae from general relativity, detection principles and approaches, and state-of-the-art equipment and detection results. In addition, we summarise the current limitations of what is known and make predictions for future directions. Gravitational waves are important because they contain information about their origin as well as about fundamental properties of gravity that cannot be detected by looking at the electromagnetic spectrum. These results shed light on guiding future research that focuses on exploring the nature of black holes.
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Chen, Xingyu, Yucheng Liu, and Ruining Zhang. "Black holes merger and the state-of-art detections." Theoretical and Natural Science 10, no. 1 (November 17, 2023): 255–60. http://dx.doi.org/10.54254/2753-8818/10/20230354.
Abstract:
Black hole mergers are fascinating astronomical phenomena that occur when two black holes gradually merge as they rotate and approach each other. This phenomenon is caused by explosive gravitational waves that propagate through space until they are detected. Black hole mergers are an extremely powerful origination as well as signature for GWs that can help us better understand the nature of the universe. Using the technology of VLBI, humans can construct the EHT and get access to the image of black holes. The EHT can resolve objects about 4000 times better than the Hubble Space Telescope thanks to this degree of precision, which enables people to perform more precise research on the exploration of the universe. At present, many research institutions around the world are involved, and a huge observation network has been established. Looking ahead, this paper finds that although humans have taken the first-ever photos of the apparent boundaries of black holes, there are still limitations to black hole detection. In future research, researchers will delve into black holes formation and evolution to reveal more about their mysteries. In addition, scientists should explore the interaction of black holes with other celestial bodies, which will help us to better understand galaxy creation and development and provide novel perspectives for the development of cosmology.
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Kirk, John G., and Iwona Mochol. "Waves in Poynting-flux dominated jets." Proceedings of the International Astronomical Union 6, S275 (September 2010): 77–81. http://dx.doi.org/10.1017/s1743921310015668.
Abstract:
AbstractHigh-energy emission from blazars is thought to arise in a relativistic jet launched by a supermassive black hole. The rapid variability of the emission suggests that structure of length scale smaller than the gravitational radius of the central black hole is imprinted on the jet as it is launched, and modulates the radiation released after it has been accelerated to high Lorentz factor. We describe a mechanism which can account for the acceleration of the jet, and for the rapid variability of the radiation, based on the propagation characteristics of nonlinear waves in charge-starved, polar jets. These exhibit a delayed acceleration phase, that kicks-in when the inertia associated with the wave currents becomes important. The time structure imprinted on the jet at launch modulates the photons produced by the accelerating jet provided that the electromagnetic cascade in the black-hole magnetosphere is not prolific.
43
LEMOS, JOSÉ P. S., and VITOR CARDOSO. "RADIATION GENERATED BY THE INFALL OF A SCALAR PARTICLE IN A SCHWARZSCHILD–ANTI-DE SITTER BACKGROUND." International Journal of Modern Physics A 17, no. 20 (August 10, 2002): 2767. http://dx.doi.org/10.1142/s0217751x02011941.
Abstract:
In the context of the AdS/CFT conjecture1, a Schwarzschild-anti-de Sitter (SAdS) black hole may be looked at as a thermal state in the CFT. Perturbing the black hole corresponds in the CFT to perturb the thermal state. We considered an important specific perturbation - the radial infall of a small test particle coupled to a scalar field into a SAdS black hole. We computed the spectra, waveforms and total scalar energy radiated during this process. For small black holes, the spectra is dominated by a resonance, and the waveform by quasinormal ringing2,3,4. For large black holes we find that the waveform quickly settles down to its final zero value, always in a quasinormal way. The approach to thermal equilibrium in the CFT is therefore dictated by the lowest quasinormal frequency. We also commented on the interpretation of the bulk process when viewed from the brane: to the black hole corresponds a thermal bath, to the infalling probe corresponds an expanding bubble, and to the scalar field waves correspond particles decaying into bosons of the associate operator of the gauge theory. For more details see5,6.
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Nitz, Alexander H., Collin D. Capano, Sumit Kumar, Yi-Fan Wang, Shilpa Kastha, Marlin Schäfer, Rahul Dhurkunde, and Miriam Cabero. "3-OGC: Catalog of Gravitational Waves from Compact-binary Mergers." Astrophysical Journal 922, no. 1 (November 1, 2021): 76. http://dx.doi.org/10.3847/1538-4357/ac1c03.
Abstract:
Abstract We present the third open gravitational-wave catalog (3-OGC) of compact-binary coalescences, based on the analysis of the public LIGO and Virgo data from 2015 through 2019 (O1, O2, O3a). Our updated catalog includes a population of 57 observations, including 4 binary black hole mergers that had not been previously reported. This consists of 55 binary black hole mergers and the 2 binary neutron star mergers, GW170817 and GW190425. We find no additional significant binary neutron star or neutron star–black hole merger events. The most confident new detection is the binary black hole merger GW190925_232845, which was observed by the LIGO–Hanford and Virgo observatories with astro > 0.99 ; its primary and secondary component masses are 20.2 − 2.5 + 3.9 M ⊙ and 15.6 − 2.6 + 2.1 M ⊙ , respectively. We estimate the parameters of all binary black hole events using an up-to-date waveform model that includes both subdominant harmonics and precession effects. To enable deep follow up as our understanding of the underlying populations evolves, we make available our comprehensive catalog of events, including the subthreshold population of candidates, and the posterior samples of our source parameter estimates.
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DE OLIVEIRA, H. P., I. DAMIÃO SOARES, and E. V. TONINI. "BLACK HOLE BREMSSTRAHLUNG: CAN IT BE AN EFFICIENT SOURCE OF GRAVITATIONAL WAVES?" International Journal of Modern Physics D 15, no. 12 (December 2006): 2203–8. http://dx.doi.org/10.1142/s0218271806009625.
Abstract:
We propose a new source of gravitational waves in the context of full nonlinear General Relativity: the black hole bremsstrahlung. A black hole initially in uniform motion is decelerated along its direction of motion; as a consequence of the deceleration, a radiative transfer process is set up through which the black hole loses its kinetic energy along with part of its rest mass by the emission of gravitational waves. Depending on the initial velocity and the strength of the deceleration, this process can correspond to a high power output in the initial pulse of gravitational radiation emitted.
46
Sago, Norichika, Soichiro Isoyama, and Hiroyuki Nakano. "Fundamental Tone and Overtones of Quasinormal Modes in Ringdown Gravitational Waves: A Detailed Study in Black Hole Perturbation." Universe 7, no. 10 (September 25, 2021): 357. http://dx.doi.org/10.3390/universe7100357.
Abstract:
Ringdown gravitational waves of compact object binaries observed by ground-based gravitational-wave detectors encapsulate rich information to understand remnant objects after the merger and to test general relativity in the strong field. In this work, we investigate the ringdown gravitational waves in detail to better understand their property, assuming that the remnant objects are black holes. For this purpose, we perform numerical simulations of post-merger phase of binary black holes by using the black hole perturbation scheme with the initial data given under the close-limit approximation, and we generate data of ringdown gravitational waves with smaller numerical errors than that associated with currently available numerical relativity simulations. Based on the analysis of the data, we propose an orthonormalization of the quasinormal mode functions describing the fundamental tone and overtones to model ringdown gravitational waves. Finally, through some demonstrations of the proposed model, we briefly discuss the prospects for ringdown gravitational-wave data analysis including the overtones of quasinormal modes.
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Riles, Keith. "Recent searches for continuous gravitational waves." Modern Physics Letters A 32, no. 39 (December 21, 2017): 1730035. http://dx.doi.org/10.1142/s021773231730035x.
Abstract:
Gravitational wave astronomy opened dramatically in September 2015 with the LIGO discovery of a distant and massive binary black hole coalescence. The more recent discovery of a binary neutron star merger, followed by a gamma ray burst (GRB) and a kilonova, reinforces the excitement of this new era, in which we may soon see other sources of gravitational waves, including continuous, nearly monochromatic signals. Potential continuous wave (CW) sources include rapidly spinning galactic neutron stars and more exotic possibilities, such as emission from axion Bose Einstein “clouds” surrounding black holes. Recent searches in Advanced LIGO data are presented, and prospects for more sensitive future searches are discussed.
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Matsuki, Yoshio, and Petro Bidyuk. "Simulating angular momentum of gravitational field of a rotating black hole and spin momentum of gravitational waves." System research and information technologies, no. 1 (March 26, 2021): 7–20. http://dx.doi.org/10.20535/srit.2308-8893.2021.1.01.
Abstract:
In this research, we simulated the angular momentum of gravitational field of a rotating black hole and the spin momentum of gravitational waves emitted from the black hole. At first, we calculated energy densities of the rotating gravitational field and spinning gravitational waves as the vectors, which were projected on the spherical curved surface of the gravitational field and of the gravitational waves. Then we calculated the angular momentum and the spin momentum as the vectors perpendicular to the curved surface. The earlier research by Paul Dirac, published in 1964, did not select the curved surface to calculate the motion of quantum particles; but, instead, he chose the flat surface to develop the theory of quantum mechanics. However, we pursued the simulation of the gravitational waves in spherical polar coordinates that form the spherical curved surface of the gravitational waves. As a result, we found that a set of anti-symmetric vectors described the vectors that were perpendicular to the spherical curved surface, and with these vectors we simulated the angular momentum of the rotating black hole’s gravitational field and the spin momentum of gravitational waves. The obtained results describe the characteristics of the rotation of a black hole and of spinning gravitational waves.
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Schenke, Sören, Fabian Sewerin, Berend van Wachem, and Fabian Denner. "Simulating acoustic waves in acoustic black hole analogues." Journal of the Acoustical Society of America 151, no. 4 (April 2022): A226. http://dx.doi.org/10.1121/10.0011141.
Abstract:
We present a physical model and a numerical method to simulate nonlinear acoustic waves emitted from moving boundaries in a moving background flow field with transition from subsonic to supersonic flow speeds. The physical model is based on a convective form of the Westervelt equation and accounts for the motion of the background medium and the progressive distortion of a finite amplitude acoustic wave. A suitable coordinate transformation in physical space allows us to accommodate the motion of the wave emitting boundary, while solving the governing equation in a fixed computational domain using standard finite difference techniques. We present the case of an oscillating spherical wave emitting boundary with an induced spherical flow as a prototypical example of an acoustic black hole analogue, where the acoustic waves cannot escape from the horizon of sonic flow speed during the contraction phase. It is demonstrated that the accelerating motion of the wave emitting boundary gives rise to frequency sidebands and amplitude modulations of the acoustic wave. The influence of the background flow speed on this nonlinear Doppler effect is investigated with the present methodology, thus contributing to an improved understanding of the acoustic wave behavior in the proximity of a sonic horizon.
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Wei, Yun-Feng, and Tong Liu. "Black Hole Hyperaccretion in Collapsars. II. Gravitational Waves." Astrophysical Journal 889, no. 2 (January 28, 2020): 73. http://dx.doi.org/10.3847/1538-4357/ab6325.