scholarly journals Gravitational wave spectra from oscillon formation after inflation

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Takashi Hiramatsu ◽  
Evangelos I. Sfakianakis ◽  
Masahide Yamaguchi
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Parametric Resonance ◽  
Wave Spectrum ◽  
Large Field ◽  
Fluctuation Analysis ◽  
Small Field ◽  
Number Density ◽  
Peak Structure ◽  
Potential Shape

Abstract We systematically investigate the preheating behavior of single field inflation with an oscillon-supporting potential. We compute both the properties of the emitted gravitational waves as well as the number density and characteristics of the produced oscillons. By performing numerical simulations for a variety of potential types, we divide the analyzed potentials in two families, each of them containing potentials with varying large- or small-field dependence. We find that the shape of the spectrum and the amplitude of emitted gravitational waves have a universal feature with the peak around the physical wavenumber k/a ∼ m at the inflaton oscillation starting period, irrespective of the exact potential shape. This can be used as a smoking-gun for deducing the existence of a violent preheating phase and possible oscillon formation after inflation. Despite this apparent universality, we also find differences in the shape of the spectrum of emitted gravitational waves between the two families of potentials, leading to discriminating features between them. In particular, all potentials show the emergence of a two-peak structure in the gravitational wave spectrum, arising at the time of oscillon formation. However, potentials that exhibit efficient parametric resonance tend to smear out this structure and by the end of the simulation the two-peak structure is replaced by one broad peak in the GW spectrum. We further compute the number density and properties of the produced oscillons for each potential choice, finding differences in the number density and size distribution of stable oscillons and transient overdensities. We also perform a linear fluctuation analysis and use the corresponding Floquet charts to relate the results of our simulations to the structure of parametric resonance for the various potential types. We find that the growth rate of the scalar perturbations and the associated oscillon formation time are sensitive to the small-field shape of a potential while the macroscopic physical properties of oscillons such as the total number depend on the large-field shape of a potential.

The development of ground based gravitational wave astronomy and opportunities for Australia–China collaboration

2015 ◽  
Vol 30 (28n29) ◽  
pp. 1545019
Author(s):  
David Blair ◽  
Li Ju ◽  
Chunnong Zhao ◽  
Linqing Wen ◽  
Qi Chu ◽  
...  
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Southern Hemisphere ◽  
Event Rate ◽  
Wave Spectrum ◽  
Current Status ◽  
Dramatic Improvement ◽  
The Universe

This paper begins by reviewing the development of gravitational wave astronomy from the first predictions of gravitational waves to development of technologies across the entire gravitational wave spectrum, and then focuses on the current status of ground based gravitational wave detectors. With substantial improvements already demonstrated in early commissioning it is emphasised that Advanced detectors are on track for first detection of gravitational waves. The importance of a worldwide array of detectors is emphasised, and recent results are shown that demonstrate the continued advantage of a southern hemisphere detector. Finally it is shown that a north–south pair of 8 km arm length detectors would give rise to a dramatic improvement in event rate, enabling a pair of detectors to encompass a 64-times larger volume of the universe, to conduct a census on all stellar mass black hole mergers to [Formula: see text] and to observe neutron star mergers to a distance of [Formula: see text][Formula: see text]800 Mpc.

Optomechanics for Gravitational Wave Detection: From Resonant Bars to Next Generation Laser Interferometers

2020 ◽  
pp. 41-104
Author(s):  
David Blair ◽  
Li Ju ◽  
Yiqiu Ma
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Wave Spectrum ◽  
Historical Context ◽  
Next Generation ◽  
Gravitational Wave Detection ◽  
Wave Detection ◽  
Laser Interferometers

This chapter reviews the 40-year history that led to the first detection of gravitational waves, and goes on to outline techniques which will allow the detectors to be substantially improved. Following a review of the gravitational wave spectrum and the early attempts at detection, it emphasizes the theme of optomechanics, and the underlying physics of parametric transducers, which creates a connection between early resonant bar detectors and modern interferometers and techniques for enhancing their sensitivity. Developments are presented in an historical context, while themes and connections between earlier and later work are emphasized.

scholarly journals The gravitational waves from the collapsing domain walls in the complex singlet model

2020 ◽  
Vol 2020 (8) ◽  
Author(s):  
Ning Chen ◽  
Tong Li ◽  
Yongcheng Wu
Keyword(s):  
Cp Violation ◽  
Domain Wall ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Domain Walls ◽  
Wave Spectrum ◽  
High Energy ◽  
Mass Scale ◽  
Spontaneous Breaking ◽  
Field Equations

Abstract We study the CP domain walls and the consequent gravitational waves induced by the spontaneous breaking of the CP symmetry in the complex singlet extension to the Standard Model. We impose the constraints from the unitarity, stability and the global minimal of the vacuum solutions on the model parameter space. The CP domain wall profiles and tensions are obtained by numerically solving the relevant field equations. The explicit CP violation terms are then introduced to the potential as biased terms to make the domain walls unstable and collapse, The BBN bound on the magnitude of the energy bias is taken into account. To achieve sufficiently strong gravitational wave signals, the domain wall tension σ is required to be at least σ/TeV3∼$$ \mathcal{O} $$ O (103). We find that the gravitational wave spectrum can be probed in the future SKA and/or DECIGO programs, when the typical mass scale is at least ∼$$ \mathcal{O} $$ O (10) TeV and the explicit CP violation terms are as small as $$ \mathcal{O} $$ O (10−24)−$$ \mathcal{O} $$ O (10−23). The gravitational waves from collapsing domain walls thus provide a complementarity to the probe of extremely small CP violation at high-energy scale.

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.

scholarly journals Monitoring Sco X-1 for the detection of gravitational waves with networks of gravitational wave detectors

2008 ◽  
Vol 120 (3) ◽  
pp. 032009 ◽  
Author(s):  
K Hayama ◽  
S Mohanty ◽  
M Rakhmanov ◽  
S Desai ◽  
T Summerscales
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Gravitational Wave Detectors

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 Beginning of Universe through large field hybrid inflation

2015 ◽  
Vol 30 (21) ◽  
pp. 1550106 ◽  
Author(s):  
Tatsuo Kobayashi ◽  
Osamu Seto
Keyword(s):  
Gravitational Wave ◽  
Early Universe ◽  
High Energy ◽  
Wave Mode ◽  
Energy Scale ◽  
Large Field ◽  
Tensor Perturbation ◽  
Expectation Value ◽  
Hybrid Inflation ◽  
High Energy Scale

Recent detection of B-mode polarization induced from tensor perturbations by the BICEP2 experiment implies the so-called large field inflation, where an inflaton field takes super-Planckian expectation value during inflation, at a high energy scale. We show however, if another inflation follows hybrid inflation, the hybrid inflation can generate a large tensor perturbation with not super-Planckian but Planckian field value. This scenario would relax the tension between BICEP2 and Planck concerning the tensor-to-scalar ratio, because a negative large running can also be obtained for a certain number of e-fold of the hybrid inflation. A natural interpretation of a large gravitational wave mode with or without the scalar spectral running might be multiple inflation in the early Universe.

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 General properties of the gravitational wave spectrum from phase transitions

2009 ◽  
Vol 79 (8) ◽  
Author(s):  
Chiara Caprini ◽  
Ruth Durrer ◽  
Thomas Konstandin ◽  
Géraldine Servant
Keyword(s):  
Phase Transitions ◽  
Gravitational Wave ◽  
Wave Spectrum ◽  
General Properties
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