scholarly journals Lensing efficiency for gravitational wave mergers

2020 ◽  
Vol 492 (3) ◽  
pp. 3359-3363 ◽  
Author(s):  
O Contigiani
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Gravitational Lensing ◽  
Mass Function ◽  
Source Population ◽  
Geometric Optics ◽  
Intrinsic Properties ◽  
Insight Into

ABSTRACT We gain insight into the effects of gravitational lensing on the estimated distribution of merging binaries observed through gravitational waves. We quantify the efficiency of magnification for gravitational wave events in the geometric optics limit, and we compare it to the electromagnetic case by making minimal assumptions about the distribution of intrinsic properties for the source population. We show that lensing effects leave a recognizable signature on the observed rates, and that they can be prominent only in the presence of an extremely steep mass function (or redshift evolution) and mainly at low inferred redshifts. We conclude that gravitational magnification does not represent a significant systematic for gravitational wave merger studies in the LIGO–Virgo era.

scholarly journals Gravitational wave–gauge field dynamics

2017 ◽  
Vol 26 (12) ◽  
pp. 1742005 ◽  
Author(s):  
R. R. Caldwell ◽  
C. Devulder ◽  
N. A. Maksimova
Keyword(s):  
Quantum Gravity ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Gauge Field ◽  
Linear Combination ◽  
Effective Mass ◽  
Normal Modes ◽  
New Approaches ◽  
Insight Into

The dynamics of a gravitational wave propagating through a cosmic gauge field are dramatically different than in vacuum. We show that a gravitational wave acquires an effective mass, is birefringent, and its normal modes are a linear combination of gravitational waves and gauge field excitations, leading to the phenomenon of gravitational wave–gauge field oscillations. These surprising results provide an insight into gravitational phenomena and may suggest new approaches to a theory of quantum gravity.

scholarly journals Probing the theory of gravity with gravitational lensing of gravitational waves and galaxy surveys

2020 ◽  
Vol 494 (2) ◽  
pp. 1956-1970 ◽  
Author(s):  
Suvodip Mukherjee ◽  
Benjamin D Wandelt ◽  
Joseph Silk
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Gravitational Lensing ◽  
Cross Correlation ◽  
Laser Interferometer ◽  
Galaxy Surveys ◽  
Einstein Telescope ◽  
Laser Interferometer Space Antenna ◽  
Theories Of Gravity ◽  
Theory Of Gravity

ABSTRACT The cross-correlation of gravitational wave strain with upcoming galaxy surveys probes theories of gravity in a new way. This method enables testing the theory of gravity by combining the effects from both gravitational lensing of gravitational waves and the propagation of gravitational waves in space–time. We find that within 10 yr the combination of the Advanced LIGO (Laser Interferometer Gravitational-Wave Observatory) and VIRGO (Virgo interferometer) detector networks with planned galaxy surveys should detect weak gravitational lensing of gravitational waves in the low-redshift Universe (z < 0.5). With the next-generation gravitational wave experiments such as Voyager, LISA (Laser Interferometer Space Antenna), Cosmic Explorer, and the Einstein Telescope, we can extend this test of the theory of gravity to larger redshifts by exploiting the synergies between electromagnetic wave and gravitational wave probes.

scholarly journals Lensing Magnification Seen by Gravitational Wave Detectors

Universe ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 19
Author(s):  
Giulia Cusin ◽  
Ruth Durrer ◽  
Irina Dvorkin
Keyword(s):  
Gravitational Wave ◽  
Gravitational Lensing ◽  
Analytic Approach ◽  
Source Population ◽  
Luminosity Distance ◽  
Wave Source ◽  
Underlying Distribution ◽  
Detector Sensitivity ◽  
Strong Lensing

In this paper, we studied the gravitational lensing of gravitational wave events. The probability that an observed gravitational wave source has been (de-)amplified by a given amount is a detector-dependent quantity which depends on different ingredients: the lens distribution, the underlying distribution of sources and the detector sensitivity. The main objective of the present work was to introduce a semi-analytic approach to study the distribution of the magnification of a given source population observed with a given detector. The advantage of this approach is that each ingredient can be individually varied and tested. We computed the expected magnification as both a function of redshift and of the observedsource luminosity distance, which is the only quantity one can access via observation in the absence of an electromagnetic counterpart. As a case study, we then focus on the LIGO/Virgo network and on strong lensing (μ>1).

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.

scholarly journals An Analysis of Gravitational waves

2021 ◽  
Author(s):  
Vaibhav Kalvakota
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Mathematical Structure ◽  
Gauge Condition ◽  
Field Tensor ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Minkowski Metric ◽  
Wave Detector ◽  
The Masses

The September 14, 2015 gravitational wave observations showed the inspiral of two black holes observed from Hanford and Livingston LIGO observatories. This detection was significant for two reasons: firstly, it coupled the result and avoided the possibility of a false alarm by 5σ , meaning that the detected “noise” was indeed from an astronomical source of gravitational waves. We will discuss the primary landscape of gravitational waves, their mathematical structure and how they can be used to predict the masses of the merger system. We will also discuss gravitational wave detector optimisations, and then we will consider the results from the detected merger GW150914. We will consider a straight-forward mathematical approach, and we will primarily be interested in the mathematical modelling of gravitational waves from General Relativity (Section 1). We will first consider a “perturbed” Minkowski metric, and then we will discuss the properties of the perturbation addition tensor. We will then discuss on the gravitational field tensor, and how it arises from the perturbation tensor. We will then talk about the gauge condition, essentially the gauge “freedom” , and then we will talk about the curvature tensor, leading eventually to the effect of gravitational waves on a ring of particles. We will consider the polarisation tensor, which maps the amplitude and polarisation details. The polarisation splits into plus polarised and cross polarised waves, which is technically the effect of a propagating gravitational wave through a ring of particles. We will then talk about the linearized Einstein Field Equations, and how the physical system of merger is encoded into the mathematical structural unity of the metric. We will then talk about the detection of these gravitational waves and how the detector can be optimised, or how the detector can be set so that any “noise” detected can fall in the error margins, and how the detector can prevent the interferometric “photon-noise” from being detected (Section 2.2). Then, we will discuss data results from the source GW150914 detection by LIGO (Section 3).

scholarly journals Classifying Lensed Gravitational Waves in the Geometrical Optics Limit with Machine Learning

2019 ◽  
Vol 16 (2) ◽  
pp. 5-16
Author(s):  
Amit Singh ◽  
Ivan Li ◽  
Otto Hannuksela ◽  
Tjonnie Li ◽  
Kyungmin Kim
Keyword(s):  
Machine Learning ◽  
Support Vector Machine ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Geometrical Optics ◽  
Supervised Machine Learning ◽  
Support Vector ◽  
Multi Layer Perceptron ◽  
Machine Learning Classifiers ◽  
Learning Classifiers

Gravitational waves are theorized to be gravitationally lensed when they propagate near massive objects. Such lensing effects cause potentially detectable repeated gravitational wave patterns in ground- and space-based gravitational wave detectors. These effects are difficult to discriminate when the lens is small and the repeated patterns superpose. Traditionally, matched filtering techniques are used to identify gravitational-wave signals, but we instead aim to utilize machine learning techniques to achieve this. In this work, we implement supervised machine learning classifiers (support vector machine, random forest, multi-layer perceptron) to discriminate such lensing patterns in gravitational wave data. We train classifiers with spectrograms of both lensed and unlensed waves using both point-mass and singular isothermal sphere lens models. As the result, classifiers return F1 scores ranging from 0:852 to 0:996, with precisions from 0:917 to 0:992 and recalls ranging from 0:796 to 1:000 depending on the type of classifier and lensing model used. This supports the idea that machine learning classifiers are able to correctly determine lensed gravitational wave signals. This also suggests that in the future, machine learning classifiers may be used as a possible alternative to identify lensed gravitational wave events and to allow us to study gravitational wave sources and massive astronomical objects through further analysis. KEYWORDS: Gravitational Waves; Gravitational Lensing; Geometrical Optics; Machine Learning; Classification; Support Vector Machine; Random Tree Forest; Multi-layer Perceptron

scholarly journals Gravitational Fields and Gravitational Waves

2021 ◽  
Author(s):  
Tony Yuan
Keyword(s):  
Gravitational Field ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Doppler Effect ◽  
Gravitational Force ◽  
Laser Interferometer ◽  
Speed Of Light ◽  
Gravitational Fields ◽  
Light Waves ◽  
Research Questions

The relative velocity between objects with finite velocity affects the reaction between them. This effect is known as general Doppler effect. The Laser Interferometer Gravitational-Wave Observatory (LIGO) discovered gravitational waves and found their speed to be equal to the speed of light c. Gravitational waves are generated following a disturbance in the gravitational field; they affect the gravitational force on an object. Just as light waves are subject to the Doppler effect, so are gravitational waves. This article explores the following research questions concerning gravitational waves: What is the spatial distribution of gravitational waves? Can the speed of a gravitational wave represent the speed of the gravitational field (the speed of the action of the gravitational field upon the object)? What is the speed of the gravitational field? Do gravitational waves caused by the revolution of the Sun affect planetary precession? Can we modify Newton’s gravitational equation through the influence of gravitational waves?

Sign in / Sign up

Export Citation Format

Share Document