scholarly journals Escape from supercooling with or without bubbles: gravitational wave signatures

2021 ◽  
Vol 81 (9) ◽  
Author(s):  
Marek Lewicki ◽  
Oriol Pujolàs ◽  
Ville Vaskonen
Keyword(s):  
Phase Transition ◽  
Gravitational Wave ◽  
Wave Spectrum ◽  
False Vacuum ◽  
Crucial Aspect ◽  
True Vacuum ◽  
Representative Model ◽  
Gravitational Wave Background ◽  
The Universe ◽  
Conformal Models

AbstractQuasi-conformal models are an appealing scenario that can offer naturally a strongly supercooled phase transition and a period of thermal inflation in the early Universe. A crucial aspect for the viability of these models is how the Universe escapes from the supercooled state. One possibility is that thermal inflation phase ends by nucleation and percolation of true vacuum bubbles. This route is not, however, always efficient. In such case another escape mechanism, based on the growth of quantum fluctuations of the scalar field that eventually destabilize the false vacuum, becomes relevant. We study both of these cases in detail in a simple yet representative model. We determine the duration of the thermal inflation, the curvature power spectrum generated for the scales that exit horizon during the thermal inflation, and the stochastic gravitational wave background from the phase transition. We show that these gravitational waves provide an observable signal from the thermal inflation in almost the entire parameter space of interest. Furthermore, the shape of the gravitational wave spectrum can be used to ascertain how the Universe escaped from supercooling.

scholarly journals Gravitational Waves from the Cosmological Quark-Hadron Phase Transition Revisited

Universe ◽  
2021 ◽  
Vol 7 (8) ◽  
pp. 304
Author(s):  
Pauline Lerambert-Potin ◽  
José Antonio de Freitas Pacheco
Keyword(s):  
Phase Transition ◽  
Gravitational Wave ◽  
Equations Of State ◽  
Wave Spectrum ◽  
Gluon Plasma ◽  
Big Bang ◽  
Einstein Equations ◽  
Black Hole Binaries ◽  
Hadron Phase ◽  
Gravitational Wave Background

The recent claim by the NANOGrav collaboration of a possible detection of an isotropic gravitational wave background stimulated a series of investigations searching for the origin of such a signal. The QCD phase transition appears as a natural candidate and in this paper the gravitational spectrum generated during the conversion of quarks into hadrons is calculated. Here, contrary to recent studies, equations of state for the quark-gluon plasma issued from the lattice approach were adopted. The duration of the transition, an important parameter affecting the amplitude of the gravitational wave spectrum, was estimated self-consistently with the dynamics of the universe controlled by the Einstein equations. The gravitational signal generated during the transition peaks around 0.28 μHz with amplitude of h02Ωgw≈7.6×10−11, being unable to explain the claimed NANOGrav signal. However, the expected QCD gravitational wave background could be detected by the planned spatial interferometer Big Bang Observer in its advanced version for frequencies above 1.0 mHz. This possible detection assumes that algorithms recently proposed will be able to disentangle the cosmological signal from that expected for the astrophysical background generated by black hole binaries.

scholarly journals Searching for cross-correlation between stochastic gravitational-wave background and galaxy number counts

2020 ◽  
Vol 500 (2) ◽  
pp. 1666-1672
Author(s):  
Kate Z Yang ◽  
Vuk Mandic ◽  
Claudia Scarlata ◽  
Sharan Banagiri
Keyword(s):  
Gravitational Wave ◽  
Cross Correlation ◽  
Sloan Digital Sky Survey ◽  
Number Count ◽  
Frequency Bands ◽  
Galaxy Count ◽  
Harmonic Decomposition ◽  
Number Counts ◽  
Gravitational Wave Background ◽  
The Universe

ABSTRACT Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo have recently published the upper limit measurement of persistent directional stochastic gravitational-wave background (SGWB) based on data from their first and second observing runs. In this paper, we investigate whether a correlation exists between this maximal likelihood SGWB map and the electromagnetic (EM) tracers of matter structure in the Universe, such as galaxy number counts. The method we develop will improve the sensitivity of future searches for anisotropy in the SGWB and expand the use of SGWB anisotropy to probe the formation of structure in the Universe. In order to compute the cross-correlation, we used the spherical harmonic decomposition of SGWB in multiple frequency bands and converted them into pixel-based sky maps in healpix basis. For the EM part, we use the Sloan Digital Sky Survey alaxy catalogue and form healpix sky maps of galaxy number counts at the same angular resolution as the SGWB maps. We compute the pixel-based coherence between these SGWB and galaxy count maps. After evaluating our results in different SGWB frequency bands and in different galaxy redshift bins, we conclude that the coherence between the SGWB and galaxy number count maps is dominated by the null measurement noise in the SGWB maps, and therefore not statistically significant. We expect the results of this analysis to be significantly improved by using the more sensitive upcoming SGWB measurements based on the third observing run of Advanced LIGO and Advanced Virgo.

Review of the possible role of self-ordering scalar fields in production of a stochastic background of gravitational waves

2015 ◽  
Vol 24 (04) ◽  
pp. 1541005
Author(s):  
James B. Dent
Keyword(s):  
Phase Transition ◽  
Scalar Field ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Scalar Fields ◽  
Inflationary Cosmology ◽  
Tensor Power ◽  
Stochastic Background ◽  
Gravitational Wave Background

A primordial gravitational wave background is a hallmark of inflationary cosmology. The recent announcement made by the BICEP2 collaboration of a possible measurement of B-mode polarization of the CMB on degree scales has produced an abundance of ideas and speculations on how such a signal constrains the inflationary paradigm, or possible alternative mechanisms of gravitational wave production. Here the possibility of a contribution to the gravitational wave background from the relaxation of a scalar field after a global phase transition is reviewed. The general contribution to the overall power is shown, and it is then demonstrated that if the BICEP2 result were to hold, this mechanism could at best produce a very small fraction of the measured tensor power.

Gravitational wave background from neutron star phase transition

2008 ◽  
Vol 41 (6) ◽  
pp. 1389-1406 ◽  
Author(s):  
José Carlos N. de Araujo ◽  
Guilherme F. Marranghello
Keyword(s):  
Phase Transition ◽  
Neutron Star ◽  
Gravitational Wave ◽  
Gravitational Wave Background

Gravitational wave background as a probe of reheating temperature of the Universe

2008 ◽  
Author(s):  
Kazunori Nakayama ◽  
S. Saito ◽  
Y. Suwa ◽  
J. Yokoyama ◽  
Pyungwon Ko ◽  
...  
Keyword(s):  
Gravitational Wave ◽  
Gravitational Wave Background ◽  
The Universe

Phase transitions and topological defects

2018 ◽  
Author(s):  
Michael Kachelriess
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Early Universe ◽  
Topological Defects ◽  
False Vacuum ◽  
First Order ◽  
Broken Symmetries ◽  
First Order Phase Transition ◽  
True Vacuum ◽  
First Order Phase

As the early universe cools down, it may perform transitions to phases with more and more broken symmetries. In a first-order phase transition, fields may be trapped in the false vacuum; the rate of the resulting tunneling process to the true vacuum is derived. Phase transitions can lead also to the formation of topological defects. Their structure and the reason for their stability are discussed.

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.

scholarly journals Constraining the nanohertz gravitational wave background with the Parkes Pulsar Timing Array

2012 ◽  
Vol 8 (S291) ◽  
pp. 177-177
Author(s):  
Ryan Shannon
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Direct Detection ◽  
Massive Black Hole ◽  
Black Hole Binaries ◽  
Pulsar Timing ◽  
The Galaxy ◽  
Gravitational Wave Background ◽  
Pulsar Timing Array ◽  
The Universe

AbstractThe direct detection of gravitational waves will usher in a new era of astrophysics, enabling the study of regions of the universe opaque to electromagnetic radiation or electromagnetically quiet. An ensemble of pulsars (referred to as a pulsar timing array) provides a set of clocks distributed across the Galaxy sensitive to gravitational waves with periods on the order of five years (frequencies of many nanohertz). Plausible source of gravitational waves in this frequency band include massive black hole binaries in the throes of mergers and oscillating cosmic strings. The stochastic gravitational wave background, the sum of gravitational waves emitted throughout the universe, is the most likely signal to be detected by a pulsar timing array.While the detection of gravitational waves will be a milestone in pulsar astronomy, a constraining limit on the strength of the gravitational wave background can be used to constrain cosmological models and early Universe physics. Here we present a new algorithm that can be used to constrain the strength of the GWB with a pulsar timing array. We then apply this technique to Parkes Pulsar Timing Array observations and place a new limit on the strength of the GWB. We conclude by discussing the astrophysical implications of this limit and the prospects for detecting gravitational waves with pulsars.

BARYOGENESIS FROM BLACK HOLE EVAPORATION

1995 ◽  
Vol 04 (04) ◽  
pp. 517-529 ◽  
Author(s):  
A.S. MAJUMDAR ◽  
P. DAS GUPTA ◽  
R.P. SAXENA
Keyword(s):  
Phase Transition ◽  
Black Holes ◽  
Black Hole ◽  
Hawking Radiation ◽  
Baryon Asymmetry ◽  
False Vacuum ◽  
Black Hole Evaporation ◽  
Inflationary Phase ◽  
The Universe

The possibility of baryogenesis through the evaporation of black holes formed during extended inflation is explored. These black holes are produced due to the collapse of trapped regions of false vacuum during the inflationary phase transition. Immediately after formation, the accretion of mass from the surrounding hot radiation bath in the universe is shown to be an important effect. This causes the lifetime of the black holes to be considerably elongated before they evaporate out through the process of Hawking radiation. It is shown that a sufficient number of black holes last up to well past the electroweak era and hence contribute to the surviving baryon asymmetry in the universe.

scholarly journals MULTIVERSE IN THE THIRD QUANTIZED HORAVA–LIFSHITZ THEORY OF GRAVITY

2012 ◽  
Vol 27 (02) ◽  
pp. 1250007 ◽  
Author(s):  
MIR FAIZAL
Keyword(s):  
Baryon Number ◽  
Scaling Factor ◽  
False Vacuum ◽  
Present Value ◽  
The Third ◽  
True Vacuum ◽  
Lifshitz Theory ◽  
Theory Of Gravity ◽  
The Universe ◽  
Detail Balance

In this paper we analyze the third quantization of Horava–Lifshitz theory of gravity without detail balance. We show that the Wheeler–DeWitt equation for Horava–Lifshitz theory of gravity in minisuperspace approximation becomes the equation for time-dependent harmonic oscillator. After interpreting the scaling factor as the time, we are able to derive the third quantized wave function for multiverse. We also show in third quantized formalism it is possible that the universe can form from nothing. Then we go on to analyze the effect of introducing interactions in the Wheeler–DeWitt equation. We see how this model of interacting universes can be used to explain baryogenesis with violation of baryon number conservation in the multiverse. We also analyze how this model can possibly explain the present value of the cosmological constant. Finally we analyze the possibility of the multiverse being formed from perturbations around a false vacuum and its decay to a true vacuum.

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