Gravitational Waves from the Cosmological Quark-Hadron Phase Transition Revisited

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.

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Escape from supercooling with or without bubbles: gravitational wave signatures

The European Physical Journal C ◽

10.1140/epjc/s10052-021-09669-6 ◽

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.

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The QCD Phase-Diagram Obtained from the NJL and the Extended-NJL Models for Quark and Hadron Phases

International Journal of Modern Physics Conference Series ◽

10.1142/s201019451760059x ◽

2017 ◽

Vol 45 ◽

pp. 1760059

Author(s):

Clebson A. Graeff ◽

Débora P. Menezes

Keyword(s):

Phase Transition ◽

Phase Diagram ◽

Equations Of State ◽

Original Formulation ◽

Qcd Phase Diagram ◽

Hadron Phase ◽

Vector Interaction ◽

Njl Model ◽

Quark Phase

We analyse the hadron/quark phase transition described by the Nambu-Jona-Lasinio (NJL) model [quark phase] and the extended Nambu-Jona-Lasinio model (eNJL) [hadron phase]. While the original formulation of the NJL model is not capable of describing hadronic properties due to its lack of confinement, it can be extended with a scalar-vector interaction so it exhibits this property, the so-called eNJL model. As part of this analysis, we obtain the equations of state within the SU(2) versions of both models for the hadron and the quark phases and determine the binodal surface.

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Effect of colour singletness of quark-gluon plasma in quark-hadron phase transition

The European Physical Journal C ◽

10.1007/s100520050314 ◽

1998 ◽

Vol 5 (4) ◽

pp. 711 ◽

Cited By ~ 2

Author(s):

Munshi Golam Mustafa ◽

Dinesh Kumar Srivastava ◽

Bikash Sinha

Keyword(s):

Phase Transition ◽

Quark Gluon Plasma ◽

Gluon Plasma ◽

Hadron Phase

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

International Journal of Modern Physics D ◽

10.1142/s0218271815410059 ◽

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.

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Gravitational wave background from neutron star phase transition

General Relativity and Gravitation ◽

10.1007/s10714-008-0712-7 ◽

2008 ◽

Vol 41 (6) ◽

pp. 1389-1406 ◽

Cited By ~ 7

Author(s):

José Carlos N. de Araujo ◽

Guilherme F. Marranghello

Keyword(s):

Phase Transition ◽

Neutron Star ◽

Gravitational Wave ◽

Gravitational Wave Background

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Principles of Gravitational-Wave Detection with Pulsar Timing Arrays

Symmetry ◽

10.3390/sym13122418 ◽

2021 ◽

Vol 13 (12) ◽

pp. 2418

Author(s):

Michele Maiorano ◽

Francesco De Paolis ◽

Achille A. Nucita

Keyword(s):

Gravitational Wave ◽

Gravitational Waves ◽

Low Frequency ◽

Black Hole Binaries ◽

Pulsar Timing ◽

Time Correlations ◽

Array Detection ◽

Square Kilometer Array ◽

Gravitational Wave Background ◽

Pulsar Timing Array

Pulsar timing uses the highly stable pulsar spin period to investigate many astrophysical topics. In particular, pulsar timing arrays make use of a set of extremely well-timed pulsars and their time correlations as a challenging detector of gravitational waves. It turns out that pulsar timing arrays are particularly sensitive to ultra-low-frequency gravitational waves, which makes them complementary to other gravitational-wave detectors. Here, we summarize the basics, focusing especially on supermassive black-hole binaries and cosmic strings, which have the potential to form a stochastic gravitational-wave background in the pulsar timing array detection band, and the scientific goals on this challenging topic. We also briefly outline the recent interesting results of the main pulsar timing array collaborations, which have found strong evidence of a common-spectrum process compatible with a stochastic gravitational-wave background and mention some new perspectives that are particularly interesting in view of the forthcoming radio observatories such as the Five hundred-meter Aperture Spherical Telescope, the MeerKAT telescope, and the Square Kilometer Array.

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The effect of differential accretion on the gravitational wave background and the present-day MBH binary population

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa2361 ◽

2020 ◽

Vol 498 (1) ◽

pp. 537-547 ◽

Cited By ~ 2

Author(s):

Magdalena S Siwek ◽

Luke Zoltan Kelley ◽

Lars Hernquist

Keyword(s):

Gravitational Wave ◽

Analytical Models ◽

Galaxy Mergers ◽

Mass Ratio ◽

Massive Black Hole ◽

Black Hole Binaries ◽

Pulsar Timing ◽

Coalescence Rate ◽

Gravitational Wave Background ◽

First Time

ABSTRACT Massive black hole binaries (MBHBs) form as a consequence of galaxy mergers. However, it is still unclear whether they typically merge within a Hubble time, and how accretion may affect their evolution. These questions will be addressed by pulsar timing arrays (PTAs), which aim to detect the gravitational wave (GW) background (GWB) emitted by MBHBs during the last Myr of inspiral. Here, we investigate the influence of differential accretion on MBHB merger rates, chirp masses, and the resulting GWB spectrum. We evolve an MBHB sample from the Illustris hydrodynamic cosmological simulation using semi-analytical models and for the first time self-consistently evolve their masses with binary accretion models. In all models, MBHBs coalesce with median total masses up to 1.5 × 108 M⊙, up to 3−4 times larger than in models neglecting accretion. In our model with the largest plausible impact, the median mass ratio of coalescing MBHBs increases by a factor 3.6, the coalescence rate by $52.3{{\ \rm per\ cent}}$, and the GWB amplitude by a factor 4.0, yielding a dimensionless GWB strain $A_{yr^{-1}} = 1 \times 10^{-15}$. Our model that favours accretion on to the primary MBH reduces the median mass ratio of coalescing MBHBs by a factor of 2.9, and yields a GWB amplitude $A_{yr^{-1}} = 3.1 \times 10^{-16}$. This is nearly indistinguishable from our model neglecting accretion, despite higher MBHB masses at coalescence. We further predict binary separation and mass ratio distributions of stalled MBHBs in the low-redshift Universe, and find that these depend sensitively on binary accretion models. This presents the potential for combined electromagnetic and GW observational constraints on merger rates and accretion models of MBHB populations.

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